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Effects of intrinsic and time-specific factors on daily nest survival of birds in a semiarid area of South America (Caatinga)

Effects of intrinsic and time-specific factors on daily nest survival of birds in a semiarid area... Revista Brasileira de Ornitologia, 24(3), 228-234 ARTICLE September 2016 Effects of intrinsic and time-specific factors on daily nest survival of birds in a semiarid area of South America (Caatinga) 1,3 2 1 Leonardo Fernandes França , Camila Melo da Silva and Luciana Vieira de Paiva Departamento de Ciências Animais, Universidade Federal Rural do Semiárido, UFERSA, Av. Francisco Mota, CEP 59625-900, Mossoró, RN, Brazil. Graduação em Ecologia, Universidade Federal Rural do Semiárido, UFERSA, Av. Francisco Mota, CEP 59625-900, Mossoró, RN, Brazil. Corresponding autor: franca_lf@ufersa.edu.br Received on 19 May 2015. Accepted on 14 September 2016. ABSTRACT: Nest predation is a determinant of reproductive success of tropical birds and its effects can vary in space, ti me and due to intrinsic factors of the species. In this study, we conducted a preliminary investigation on changes in the risk of nest predation on Caatinga birds due to intrinsic factors (nest type and taxonomic group) and time-specific factors (bree ding season and nest abundance). We located and monitored bird nests during the breeding seasons of 2012 (n = 33 nests) and 2013 (n = 45) in a mixed landscape of anthropogenic and natural sites. We use the MARK program that uses known-fate models to calculate Daily Nest Survival Estimates (DNS) and evaluate the effect of covariates on DNS estimates. Predation was the main cause of nest loss (n = 54). In the analysis of intrinsic factors, the best model included the type of nest to explain variation in estimates. DNS declined across the breeding season for all nest types, but estimates of closed nests (between 0.996 and 0.851) were higher than those of open nests (between 0.985 and 0.629). For time-specific factors, the best models for each breeding season included the quadratic effect of nest abundance to explain the variation in DNS. There was an inverse relationship between the abundance of nests and nest predation. The high i mportance of predation and the effect of the type of nest showe d that the reproductive success of the birds studied is due to similar factors to those found in other Neotropical environments. On the other hand, locally-specific effects, such as low reproductive success and inverse relationship between abundance and nest predation risk, demonstrate the need for further exploration of this theme within the Caatinga avifauna. KEY-WORDS: avian, density-dependence, predation, reproductive success. INTRODUCTION Thompson-III 2007, Wilson et al. 2007, França & Marini 2009b). Predation rates can also be determined by Interactions such as predation, competition and brood spatially varying factors, for example, between different parasitism may result in temporal and spatial variations in types of habitat, variation in nest building sites and density of co-specific nests (Burhans et al. 2002, Roos reproductive success in birds (Gates & Gysel 1978, Martin 1995, Woodworth 1999). Among these, predation is the 2002, Peak et al. 2004, Mahon & Martin 2006, Aguilar primary cause of nest mortality (Ricklefs 1969), especially et al. 2008). Finally, predation rates may be linked to for Neotropical birds (França & Marini 2009b, Marini et intrinsic reproductive factors such as nest type, parental al. 2009a, Dias & Macedo 2011), and can result in the loss behavior or even morphological and behavioral patterns inherent to taxonomic order of the prey species (Martin of some 70% of passerine clutches (Robinson et al. 2000, Stutchbury & Morton 2001). The high i mpact of nest & Clobert 1996, Martin et al. 2000, Robinson et al. predation on breeding success of Neotropical birds makes 2000, Borges & Marini 2010, Dias et al. 2010). this interaction an important part of the dynamics of bird In northeastern Brazil the xeric vegetation type populations in these environments, and knowledge of its (Caatinga) is characterized by high seasonality, irregularity and lack of rain (Prado 2003, Silva et al. 2003, Leal et operation is key for effective conservation (Stutchbury & Morton 2001). al. 2005), all of which can both regulate and restrict the Fluctuations in nest predation rates may be related breeding season for birds (Cavalcanti 2014), and result to time-specific factors that vary across the breeding in time-dependent fluctuations in nest predation rates. season, during nest development or between breeding Bird breeding in Caatinga seems to be scheduled to coincide with the rainy season (Nascimento et al. 2000, seasons (Martin et al. 2000, Roos 2002, Peak et al. 2004, Revista Brasileira de Ornitologia, 24(3), 2016 Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva Telino-Júnior et al. 2005, Roos et al. 2006) when, over most of the year (Prado 2003). Natural vegetation consists a short time period, many species simultaneously invest mainly of woody and herbaceous species, small and in nest production (Cavalcanti 2014). This temporal completely deciduous during the dry season (Velloso et al. concentration of breeding activity generates resource 2002, Prado 2003). The study presented here occurred in availability peaks for nest predators and can result in an area of Caatinga (5°03'54''S; 37°24'03''W, 76 m a.s.l.), density-dependent relationships between predator in the state of Rio Grande do Norte, in the Depressão and prey (Aguilar et al. 2008). In addition to extrinsic Sertaneja Setentrional (Dry Northern Depression) region factors, some intrinsic factors may be important sources (Velloso et al. 2002). The study area encompasses some of variation in nest predation rates in the Caatinga. The 400 ha, and comprises a mixed landscape of areas of native high local richness of bird species in Caatinga (from 70 Caatinga vegetation and human-use areas with different to 145 species: Santos 2004, Farias et al. 2005, Olmos et levels and types of impacts. Nest sampling occurred in the al. 2005, Telino-Júnior et al. 2005, Farias 2007, Araujo areas disturbed by perennial or seasonal plant cultivation, & Rodrigues 2011) when compared to other semi-arid areas where local beekeeping occurred and in abandoned environments (e.g. n ≤ 25, northeastern Venezuela, Poulin areas of agricultural experiments. et al. 1993; n ≤ 54, western Mexico, Del-R & Butterfield 1999; n ≤ 61, northcentral Chile, Jaksic & Lazo 1999) Data sampling and analysis can result in greater variability of such intrinsic factors as nest type, breeding and social behavior, and generate We conducted active searches for bird nests at likely particular predation patterns not found in other tropical nesting sites to calculate the estimates of Daily Nest semiarid areas. Survival (DNS) and daily nest abundance in the study Most studies evaluating nest predation in seasonal area. Nests were searched for between March and May Neotropics have occurred in the Cerrado (e.g. Francisco 2012, and between February and June 2013. Nests were 2006, Carvalho et al. 2007, Aguilar et al. 2008, França also located by following individuals exhibiting behavior & Marini 2009b, Marini et al. 2009a, Borges & Marini indicating the nearby presence of a nest. Found nests 2010, Marini et al. 2010, Hoffmann & Rodrigues 2011, were visited at regular intervals of three and four days Marini et al. 2012). Caatinga weather conditions are more until they became inactive. For each nest we identified severe than those of the Cerrado, with higher rates of the incubator species and classified nest type (open or solar radiation, average annual temperature and potential closed). During each monitoring event we recorded evapotranspiration, and lower relative humidity rates and the date, nest status (active or inactive) and type of nest annual precipitation (Prado 2003). Avian ecology and contents (empty, eggs or nestlings). We considered a nest conservation from the Caatinga are considered the least- successful when at least one of the nestlings survived known among Brazilian ecoregions (Marini & Garcia long enough to fle dge and leave the nest. Nest status was 2005). In view of the lack of information concerning defined as preyed upon when all the eggs or nestlings factors influencing predation risk of bir d nests in seasonal disappeared from the nest before the minimum period Neotropical environments, the present study aimed to test required for hatching or nestling departure had ended, the following hypotheses: (1) closed nests are less likely to and/or when obvious signs of predation on eggs or suffer predation than open nests (as has been reported nestlings were observed. This form of search and nest in other humid and seasonal tropical environments in monitoring procedure is commonly used in studies the Neotropics - Oniki 1979, Purcell & Verner 1999, estimating reproductive success (e.g. Johnson et al. 2006, Robinson et al. 2000); (2) the risk of nest predation França et al. 2009, Marini et al. 2012). varies between bird taxonomic Orders (Borges & Marini All data analyses were performed with the program 2010); (3) the abundance of active nests is related to daily MARK (Dinsmore et al. 2002). We used capture- fluctuations in predation risk (Ackerman et al. 2004, recapture models based on known-fate models to generate Paiva 2008, Elmberg & Pöysä 2011). the estimates of Daily Nest Survival (DNS), and evaluate the effects of temporal and intrinsic covariates on these estimates. To create models, we combined covariates METHODS considered to affect the variation in nest survival. The covariates considered were: (1) linear and quadratic Study area effects of the breeding season on the probability of DNS (season and season ); (2) linear and quadratic effects of The Caatinga ecoregion occurs in northeastern Brazil nest abundance on the estimates of DNS (nest and nest ); at altitudes ranging from 0–600 m. The average annual (3) effect of nest type, either open or closed nests (type) temperature varies between 24 and 28°C and total annual and; (4) effect of taxonomic Or der (Columbiformes, rainfall from 250–1000 mm, with a high water deficit for Passeriformes and Psittaciformes) of the species under Revista Brasileira de Ornitologia, 24(3), 2016 Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva investigation. We used a method that compared a We conducted two analyses of candidate models null model with a set of candidate models. We created to test the study hypotheses and the different data types candidate models by combining covariates thought collected in the two breeding seasons. The first analysis to explain the variation in DNS. For the covariate nest considered only data from the first bree ding season, and abundance, we used our records of the number of active evaluated the effect of intrinsic factors on estimates of nests from daily monitoring. Monitoring events occurred DNS. This was the only season in which we sa mpled at fixed intervals of three and four days, and during closed nests. The second analysis considered only open this time a pair of researchers sought new nests. Daily nests for the two breeding seasons, to evaluate the effect monitoring occurred from 4 to 6 h/day. of temporally varying factors on estimates of DNS. To select the best model among the set of candidate models, we ordered models with the Akaike Information Criterion (Burnham & Anderson 1998). Models with RESULTS best fit were those with t he lowest AIC and also models The main factor influencing reproductive success in the with ΔAICc ≤ 2, as these are considered to possess substantial support to explain part of the within-data study area was nest predation (n = 54 predated nests and variation (Burnham & Anderson 1998). We estimated 24 successful). To test for intrinsic factors we analyzed reproductive success through the logistic function of the 33 nests sampled in 2012. The candidate model with best model, using a period of 27 days between egg laying the best support for the observed variation included the covariates reproductive period and nest type (Table 1). and nestling flight. This period is within the 24 to 28 days range of development for seven of the fully monitored The next models in the adjustment or der were not able nests from the study, and is similar to durations reported by to explain the variance in the data (ΔAICc ≥ 3.53). The other studies on Neotropical passerines (Lopes & Marini best fit model explained 70% of variance from t he set of 2005a, Medeiros & Marini 2007, Duca & Marini 2011). candidate models. TABLE 1. Candidate models considered for evaluating the effect of intrinsic factors in the variation of DNS (Daily Nest Survival) estimates in the 2012 breeding season at the Caatinga, Brazil. Selection was based on Akaike Information Criterion with correction for small samples (AIC ). The w-AIC is the support of each model in relation to the set of candidate models. K represents the number of parameters of each model. Model AIC ΔAIC w-AIC KDeviance c c c Season + type 104.44 0.00 0.70 3 98.36 Season + order + type 107.98 3.53 0.11 6 95.70 Season + order 108.76 4.32 0.08 5 98.56 Type 109.88 5.44 0.04 2 105.85 Constant 110.63 6.18 0.03 1 108.62 Order 112.55 8.10 0.01 4 104.41 Type + order 113.09 8.64 0.00 5 102.89 According to the best fitting model, the DNS for 1.0 closed and open nests decreased as the breeding season 0.9 progressed, but closed nests had higher values (Figure 0.8 1). In the first 10 days of the breeding season, the DNS estimates tended to decrease at a lower rate (closed nests 0.7 = 0.996 to 0.992, open nests = 0.985 to 0.972) than in 0.6 the last 10 days (closed nests = 0.917 to 0.851, open Closed nests 0.5 nests = 0.767 to 0.629; Figure 1). Closed nests had high Open nests estimates of reproductive success early in the season 0.4 1 4 7 1013161922252831343740434649 (69.8%), and values up to 5.3 times lower at the end of Reproductive season (days) the season (13.2%). Reproductive success for open nests FIGURE 1. Daily Nest Survival (DNS) estimates for open and closed ranged from 30.5% at the beginning of the season and nests during the first bree ding season (2012) at Caatinga, Brazil. close to zero at the end (Figure 2). The difference between Results are based on analyses of the best fitting candidate models. nest types ranged from around 56% at breeding season Linear equation of the best model: DNS = 4.286 -0.074 (breeding season) + 1.216 (type of nest). start to 13% at the end. Revista Brasileira de Ornitologia, 24(3), 2016 Daily Nest Survival Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva of candidate models, and the two best models together Closed nests Open nests explained 73% of the variation (Table 2). We present the results of the best model (nests ) for discussion. During the 2013 breeding season 14 nests were successful and 31 were predated. In this analysis the best adjusted model was also that one which considered the quadratic effect on the nest abundance to explain variations in DNS (Table 2). The next model in the adjustment or der (ΔAIC = 7.27), and the null model (ΔAIC = 8.87), had no support beginning middle end for explaining the variations in the data. The best fitted Reproductive season model explained 94% of variance considered by the set FIGURE 2. Reproductive success estimation (%) for open and closed nests according to three nesting start dates during the breeding season of candidate models (Table 2). We used the best model (beginning, middle and end), with a period of 27 days between egg 2 (nest ) to generate the estimates of DNS. laying and fledgling flight. DNS tended to increase during periods of low daily Evaluation of the effect of time-dependent factors nest abundance records. During the 2012 breeding season, was based on 24 and 45 open nests from the 2012 and DNS ranged from 0.743 to 0.946 with 5 to 10 active 2013 breeding seasons, respectively. During the first nests per day being recorded. In the 2013 breeding season breeding season, seven nests were successful and 17 were DNS ranged from 0.831 to 0.952 with 2 to 7 active nests preyed upon. Two candidate models showed substantial per day being recorded (Figure 3). In periods of higher support to explain the variation in DNS estimates, and recorded nest abundance, DNS tended to decrease in the the best model was that one which considered the effects 2012 breeding season, but was more constant in 2013. of the covariate nest abundance (Table 2). The best model During the 2012 breeding season, DNS decreased from was affected by the quadratic effect of nest abundance, 0.969 to 0.919, with 17 to 22 active nests recorded daily, while in the second model (ΔAIC = 0.84), DNS was while in 2013 DNS values oscillated between 0.977 affected by the linear effect of bree ding season. The best and 0.975, with 13 to 18 active nests recorded daily model explained 44% of variance considered by the set (Figure 3). Reproductive success estimates for open nests TABLE 2. Candidate models considered for evaluating the effect of covariates for time-specific variation of DNS (Daily Nest Survival) estimates for open nests during two studied breeding seasons in Caatinga, Brazil. Selection was based on Akaike Information Criterion with correction for small samples (AIC ). The w-AIC is the support of each model in relation to the set of candidate models. K represents the number of parameters of each model. c c Model AIC ΔAIC w-AIC KDeviance c c c 2012 Breeding season Nests 60.64 0.00 0.44 3 54.48 Season 61.48 0.83 0.29 2 57.40 Season 63.07 2.42 0.13 3 56.91 Nests 63.32 2.67 0.11 2 59.24 Constant 66.84 6.20 0.01 1 64.82 2013 Breeding season Nests 134.98 0.00 0.94 3 128.92 Nests 142.25 7.26 0.02 2 138.22 Constant 143.85 8.86 0.01 1 141.84 Season 144.23 9.25 0.00 2 140.20 Season 144.71 9.72 0.00 3 138.65 1.00 1.00 (A) (A) (B (B) 0.95 0.95 0.90 0.90 0.85 0.85 0.80 0.80 0.75 0.75 0.70 0.70 0 5 10 15 20 25 0 5 10 15 20 Nest abundance Nest abundance FIGURE 3. Daily Nest Survival (DNS) estimates for open nests with nest abundance considered (quadratic effect), during the 2012 (A) and 2013 (B) breeding seasons at Caatinga, Brazil. Results are based on the best model from the analysis of candidate models. Linear equation of the best 2 2 models: (A) DNS = -1.928 + 0.715 (nests) -0.023 (nests ) and (B) DNS = 0.841 + 0.403 (nests) -0.014 (nests ). Revista Brasileira de Ornitologia, 24(3), 2016 Reproductive success (%) Daily Nest Survival Daily Nest Survival Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva were low (Figure 4). During the 2012 breeding season frequency may be directly related to density (Gates & reproductive success ranged from very low to almost Gysel 1978, Roos 2002, Aguilar et al. 2008, Paiva 2008, zero (7.4 to 0.01% of successful nests). During the 2013 Dias et al. 2010). breeding season reproductive success declined from Our results have found a different effect to that the beginning and middle of the breeding season, then commonly reported in the literature, and indicate a direct increased again to peak at the end of the season (15.1%). relationship between the abundance of nests and estimates of DNS. In other words, an inverse relationship between 2012 2013 the abundance of nests and their risk of predation. This may have climatic links. The bree ding season in the Caatinga is among the shortest reported for any seasonal Neotropical environment (Cavalcanti 2014), possibly due to the short rainy season and associated period of adequate food availability. In 2013 the breeding season at the current study site lasted only 87 days (active nests) (Cavalcanti 2014). It is possible that this brevity results beginning middle end in an avian breeding season so short, intense, widespread Reproductive season and temporally contiguous as to generate rapid predator FIGURE 4. Reproductive success estimate (%) with open nests at satiation. In such a situation, prey consumption rates Caatinga, Brazil, according to three nest start dates (beginning, middle may depend simply on the intake ability and digestive and end) during the 2012 and 2013 breeding seasons, and with a capacity of individual predators (Jeschke et al. 2002). period of 27 days between egg laying and nestling flight. When satiation is achieved hunting activities decrease, lowering predation rates (Jeschke et al. 2002). According DISCUSSION to this hypothesis, a rapid predator satiation process may result in the inverse relationship between the abundance Predation was the main cause of nest failure during and predation rate of nests, as we observed at this this study. This parallels observations made in Cerrado Caatinga site. We recorded low levels of avian reproductive success, (Carvalho et al. 2007, Medeiros & Marini 2007, Aguilar and a marked variation between the two study years et al. 2008, França & Marini 2009a, Borges & Marini 2010), Amazonia (Oniki 1979, Mullner & Linsenmair (2012, 0.01 to 7% and 2013, 10% to 15%). Reports of 2007) and Atlantic Forest (Duca & Marini 2005, Duca reproductive success for other seasonal Neotropical areas & Marini 2008). In our study closed nests had higher are generally higher than those recorded (Cerrado - Suiriri affinis 32%, Suiriri islerorum 10%, Lopes & Marini success, and this also has been commonly observed in 2005b; Elaenia chiriquensis 33%, Medeiros & Marini both Neotropical (Oniki 1979, Robinson et al. 2000, Duca & Marini 2005, Duca & Marini 2008, Faria et al. 2007; Tyrannus savana 52.5%, Marini et al. 2009a; 2008) and temperate areas (Purcell & Verner 1999). It Elaenia cristata 27.1%, Marini et al. 2009b; Mimus is assumed that closed nests are under lower predation saturninus 54%, Rodrigues 2009). For some species, breeding success values close to those of the current study rates due to the reduced accessibility of nest contents to have been reported (Amazonia - Cercomacra tyrannina predators (Oniki 1979). Our data provide evidence that the characteristic feature of the semiarid Caatinga, with 7.1%, Robinson et al. 2000; Cerrado - Volatinia jacarina high unpredictability in the availability and distribution 4.7%, Carvalho et al. 2007; Cerrado – S. islerorum 16.8 of rainfall (Prado 2003), is not a factor that changes the and 6.7%, França & Marini 2009b). A study in Cerrado has shown that overall bird community breeding success overall Neotropical pattern of high nest predation rates in areas under high human impact (16.6%) may be less on all types of nests. Few studies have considered the processes responsible than those in more natural areas (29.4%) (Borges & for temporal variation in predation in Neotropical bird Marini 2010). We report here the lowest reproductive nests. Results presented here indicate a temporal effect success values so far encountered in the Neotropics, and this may be a consequence of the high levels of human of nest abundance in the Daily Nest Survival. Predator- impact on the study site vegetation, the mosaic nature of prey interactions are commonly considered to be related to density-dependent effects (e.g. Gates & Gysel 1978, the landscape, or the unique nature of Caatinga rainfall Oliveira et al. 2001, Oro et al. 2006), and some of these patterns. While it is difficult to determine which of these is are involved during nest predation (Gates & Gysel 1978, the dominant cause for the low breeding success observed, these results highlight the vulnerability of local Caatinga Bêty et al. 2002, Roos 2002, Paiva 2008). In such studies, bird populations, as heavy nest predation pressure could variation in the risk of nest predation may have arisen from a functional response by predators, so that predation make human-impacted vegetation fragments potentially Revista Brasileira de Ornitologia, 24(3), 2016 Reproductive success (%) Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva Dias, R. I. & Macedo, R. H. 2011. Nest predation versus resources inviable, as either population sources or sinks for the local in a Neotropical passerine: constraint of the food limitation avifauna. hypothesis. Ornis Fennica, 88: 30–39. This study is one of the first to establish t he current Dinsmore, S. J.; White, G. C. & Knopf, F. L. 2002. Advanced patterns of variation in breeding success for Caatinga techniques for modeling avian nest survival. Ecology, 83: 3476– birds. The pronounced i mportance of predation and 3488. Duca, C. & Marini, M. Â. 2005. Temporal variation in the the effect of the type of nest demonstrated by this reproductive success of Cacicus haemorrhous (Linnaeus) (Aves, study show that breeding success for Caatinga birds are Icterinae) in an Atlantic Forest reserve in southeast Brazil. Revista governed by processes similar to those found in other Brasileira de Zoologia, 22: 484–489. Neotropical environments. On the other hand, the local Duca, C. & Marini, M. Â. 2008. Breeding success of Cacicus haemorrhous (Linnaeus) (Aves: Icteridae) in different environments characteristics of inverse dependence between abundance in an Atlantic Forest reserve in southeast Brazil. 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Avifauna em quatro áreas de Caatinga strictu Rural do Semi-Árido for their help with field work. We senso no centro-oeste de Pernambuco, Brasil. Revista Brasileira de thank FAPERN (Edital 005/2011, Grant No. 57) for Ornitologia, 15: 53–60. funding the research of LFF. Farias, G. B.; Silva, W. A. G. & Albano, C. G. 2005. Diversidade de aves em áreas prioritárias para a conservação da Caatinga, p. 204–226. In: Araújo, F. S.; Rodal, M. J. N. & Barbosa, M. R. V. (eds.). Análise das variações da biodiversidade do Bioma Catinga: REFERENCES suporte a estratégias regionais de conservação. Brasilia: Ministério do Meio Ambiente. Ackerman, J. T.; Blackmer, A. L. & Eadie, J. M. 2004. Is predation França, L. C. & Marini, M. Â. 2009a. Teste do efeito de borda na on waterfowl nests density dependent?– Tests at three spatial predação de ninhos naturais e artificiais no Cerrado. Zoologia, 26: scales. Oikos, 107: 128–140. 241–250. Aguilar, T. M.; Dias, R. I.; Oliveira, A. C. & Macedo, R. H. 2008. 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Modeling population dynamics of a do Brasil: composição, riqueza e similaridade. Papéis Avulsos de songbird exposed to parasitism and predation and evaluating Zoologia, 45: 179–199. management options. Conservation Biology, 13: 67–76. Oniki, Y. 1979. Is nesting success of birds low in the tropics? Biotropica, 11: 60–69. Oro, D.; Martínez-Abraín, A.; Paracuellos, M.; Nevado, J. C. & Genovart, M. 2006. Influence of density dependence on Associate Editor: Alexandre Aleixo. Revista Brasileira de Ornitologia, 24(3), 2016 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Ornithology Research Springer Journals

Effects of intrinsic and time-specific factors on daily nest survival of birds in a semiarid area of South America (Caatinga)

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Revista Brasileira de Ornitologia, 24(3), 228-234 ARTICLE September 2016 Effects of intrinsic and time-specific factors on daily nest survival of birds in a semiarid area of South America (Caatinga) 1,3 2 1 Leonardo Fernandes França , Camila Melo da Silva and Luciana Vieira de Paiva Departamento de Ciências Animais, Universidade Federal Rural do Semiárido, UFERSA, Av. Francisco Mota, CEP 59625-900, Mossoró, RN, Brazil. Graduação em Ecologia, Universidade Federal Rural do Semiárido, UFERSA, Av. Francisco Mota, CEP 59625-900, Mossoró, RN, Brazil. Corresponding autor: franca_lf@ufersa.edu.br Received on 19 May 2015. Accepted on 14 September 2016. ABSTRACT: Nest predation is a determinant of reproductive success of tropical birds and its effects can vary in space, ti me and due to intrinsic factors of the species. In this study, we conducted a preliminary investigation on changes in the risk of nest predation on Caatinga birds due to intrinsic factors (nest type and taxonomic group) and time-specific factors (bree ding season and nest abundance). We located and monitored bird nests during the breeding seasons of 2012 (n = 33 nests) and 2013 (n = 45) in a mixed landscape of anthropogenic and natural sites. We use the MARK program that uses known-fate models to calculate Daily Nest Survival Estimates (DNS) and evaluate the effect of covariates on DNS estimates. Predation was the main cause of nest loss (n = 54). In the analysis of intrinsic factors, the best model included the type of nest to explain variation in estimates. DNS declined across the breeding season for all nest types, but estimates of closed nests (between 0.996 and 0.851) were higher than those of open nests (between 0.985 and 0.629). For time-specific factors, the best models for each breeding season included the quadratic effect of nest abundance to explain the variation in DNS. There was an inverse relationship between the abundance of nests and nest predation. The high i mportance of predation and the effect of the type of nest showe d that the reproductive success of the birds studied is due to similar factors to those found in other Neotropical environments. On the other hand, locally-specific effects, such as low reproductive success and inverse relationship between abundance and nest predation risk, demonstrate the need for further exploration of this theme within the Caatinga avifauna. KEY-WORDS: avian, density-dependence, predation, reproductive success. INTRODUCTION Thompson-III 2007, Wilson et al. 2007, França & Marini 2009b). Predation rates can also be determined by Interactions such as predation, competition and brood spatially varying factors, for example, between different parasitism may result in temporal and spatial variations in types of habitat, variation in nest building sites and density of co-specific nests (Burhans et al. 2002, Roos reproductive success in birds (Gates & Gysel 1978, Martin 1995, Woodworth 1999). Among these, predation is the 2002, Peak et al. 2004, Mahon & Martin 2006, Aguilar primary cause of nest mortality (Ricklefs 1969), especially et al. 2008). Finally, predation rates may be linked to for Neotropical birds (França & Marini 2009b, Marini et intrinsic reproductive factors such as nest type, parental al. 2009a, Dias & Macedo 2011), and can result in the loss behavior or even morphological and behavioral patterns inherent to taxonomic order of the prey species (Martin of some 70% of passerine clutches (Robinson et al. 2000, Stutchbury & Morton 2001). The high i mpact of nest & Clobert 1996, Martin et al. 2000, Robinson et al. predation on breeding success of Neotropical birds makes 2000, Borges & Marini 2010, Dias et al. 2010). this interaction an important part of the dynamics of bird In northeastern Brazil the xeric vegetation type populations in these environments, and knowledge of its (Caatinga) is characterized by high seasonality, irregularity and lack of rain (Prado 2003, Silva et al. 2003, Leal et operation is key for effective conservation (Stutchbury & Morton 2001). al. 2005), all of which can both regulate and restrict the Fluctuations in nest predation rates may be related breeding season for birds (Cavalcanti 2014), and result to time-specific factors that vary across the breeding in time-dependent fluctuations in nest predation rates. season, during nest development or between breeding Bird breeding in Caatinga seems to be scheduled to coincide with the rainy season (Nascimento et al. 2000, seasons (Martin et al. 2000, Roos 2002, Peak et al. 2004, Revista Brasileira de Ornitologia, 24(3), 2016 Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva Telino-Júnior et al. 2005, Roos et al. 2006) when, over most of the year (Prado 2003). Natural vegetation consists a short time period, many species simultaneously invest mainly of woody and herbaceous species, small and in nest production (Cavalcanti 2014). This temporal completely deciduous during the dry season (Velloso et al. concentration of breeding activity generates resource 2002, Prado 2003). The study presented here occurred in availability peaks for nest predators and can result in an area of Caatinga (5°03'54''S; 37°24'03''W, 76 m a.s.l.), density-dependent relationships between predator in the state of Rio Grande do Norte, in the Depressão and prey (Aguilar et al. 2008). In addition to extrinsic Sertaneja Setentrional (Dry Northern Depression) region factors, some intrinsic factors may be important sources (Velloso et al. 2002). The study area encompasses some of variation in nest predation rates in the Caatinga. The 400 ha, and comprises a mixed landscape of areas of native high local richness of bird species in Caatinga (from 70 Caatinga vegetation and human-use areas with different to 145 species: Santos 2004, Farias et al. 2005, Olmos et levels and types of impacts. Nest sampling occurred in the al. 2005, Telino-Júnior et al. 2005, Farias 2007, Araujo areas disturbed by perennial or seasonal plant cultivation, & Rodrigues 2011) when compared to other semi-arid areas where local beekeeping occurred and in abandoned environments (e.g. n ≤ 25, northeastern Venezuela, Poulin areas of agricultural experiments. et al. 1993; n ≤ 54, western Mexico, Del-R & Butterfield 1999; n ≤ 61, northcentral Chile, Jaksic & Lazo 1999) Data sampling and analysis can result in greater variability of such intrinsic factors as nest type, breeding and social behavior, and generate We conducted active searches for bird nests at likely particular predation patterns not found in other tropical nesting sites to calculate the estimates of Daily Nest semiarid areas. Survival (DNS) and daily nest abundance in the study Most studies evaluating nest predation in seasonal area. Nests were searched for between March and May Neotropics have occurred in the Cerrado (e.g. Francisco 2012, and between February and June 2013. Nests were 2006, Carvalho et al. 2007, Aguilar et al. 2008, França also located by following individuals exhibiting behavior & Marini 2009b, Marini et al. 2009a, Borges & Marini indicating the nearby presence of a nest. Found nests 2010, Marini et al. 2010, Hoffmann & Rodrigues 2011, were visited at regular intervals of three and four days Marini et al. 2012). Caatinga weather conditions are more until they became inactive. For each nest we identified severe than those of the Cerrado, with higher rates of the incubator species and classified nest type (open or solar radiation, average annual temperature and potential closed). During each monitoring event we recorded evapotranspiration, and lower relative humidity rates and the date, nest status (active or inactive) and type of nest annual precipitation (Prado 2003). Avian ecology and contents (empty, eggs or nestlings). We considered a nest conservation from the Caatinga are considered the least- successful when at least one of the nestlings survived known among Brazilian ecoregions (Marini & Garcia long enough to fle dge and leave the nest. Nest status was 2005). In view of the lack of information concerning defined as preyed upon when all the eggs or nestlings factors influencing predation risk of bir d nests in seasonal disappeared from the nest before the minimum period Neotropical environments, the present study aimed to test required for hatching or nestling departure had ended, the following hypotheses: (1) closed nests are less likely to and/or when obvious signs of predation on eggs or suffer predation than open nests (as has been reported nestlings were observed. This form of search and nest in other humid and seasonal tropical environments in monitoring procedure is commonly used in studies the Neotropics - Oniki 1979, Purcell & Verner 1999, estimating reproductive success (e.g. Johnson et al. 2006, Robinson et al. 2000); (2) the risk of nest predation França et al. 2009, Marini et al. 2012). varies between bird taxonomic Orders (Borges & Marini All data analyses were performed with the program 2010); (3) the abundance of active nests is related to daily MARK (Dinsmore et al. 2002). We used capture- fluctuations in predation risk (Ackerman et al. 2004, recapture models based on known-fate models to generate Paiva 2008, Elmberg & Pöysä 2011). the estimates of Daily Nest Survival (DNS), and evaluate the effects of temporal and intrinsic covariates on these estimates. To create models, we combined covariates METHODS considered to affect the variation in nest survival. The covariates considered were: (1) linear and quadratic Study area effects of the breeding season on the probability of DNS (season and season ); (2) linear and quadratic effects of The Caatinga ecoregion occurs in northeastern Brazil nest abundance on the estimates of DNS (nest and nest ); at altitudes ranging from 0–600 m. The average annual (3) effect of nest type, either open or closed nests (type) temperature varies between 24 and 28°C and total annual and; (4) effect of taxonomic Or der (Columbiformes, rainfall from 250–1000 mm, with a high water deficit for Passeriformes and Psittaciformes) of the species under Revista Brasileira de Ornitologia, 24(3), 2016 Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva investigation. We used a method that compared a We conducted two analyses of candidate models null model with a set of candidate models. We created to test the study hypotheses and the different data types candidate models by combining covariates thought collected in the two breeding seasons. The first analysis to explain the variation in DNS. For the covariate nest considered only data from the first bree ding season, and abundance, we used our records of the number of active evaluated the effect of intrinsic factors on estimates of nests from daily monitoring. Monitoring events occurred DNS. This was the only season in which we sa mpled at fixed intervals of three and four days, and during closed nests. The second analysis considered only open this time a pair of researchers sought new nests. Daily nests for the two breeding seasons, to evaluate the effect monitoring occurred from 4 to 6 h/day. of temporally varying factors on estimates of DNS. To select the best model among the set of candidate models, we ordered models with the Akaike Information Criterion (Burnham & Anderson 1998). Models with RESULTS best fit were those with t he lowest AIC and also models The main factor influencing reproductive success in the with ΔAICc ≤ 2, as these are considered to possess substantial support to explain part of the within-data study area was nest predation (n = 54 predated nests and variation (Burnham & Anderson 1998). We estimated 24 successful). To test for intrinsic factors we analyzed reproductive success through the logistic function of the 33 nests sampled in 2012. The candidate model with best model, using a period of 27 days between egg laying the best support for the observed variation included the covariates reproductive period and nest type (Table 1). and nestling flight. This period is within the 24 to 28 days range of development for seven of the fully monitored The next models in the adjustment or der were not able nests from the study, and is similar to durations reported by to explain the variance in the data (ΔAICc ≥ 3.53). The other studies on Neotropical passerines (Lopes & Marini best fit model explained 70% of variance from t he set of 2005a, Medeiros & Marini 2007, Duca & Marini 2011). candidate models. TABLE 1. Candidate models considered for evaluating the effect of intrinsic factors in the variation of DNS (Daily Nest Survival) estimates in the 2012 breeding season at the Caatinga, Brazil. Selection was based on Akaike Information Criterion with correction for small samples (AIC ). The w-AIC is the support of each model in relation to the set of candidate models. K represents the number of parameters of each model. Model AIC ΔAIC w-AIC KDeviance c c c Season + type 104.44 0.00 0.70 3 98.36 Season + order + type 107.98 3.53 0.11 6 95.70 Season + order 108.76 4.32 0.08 5 98.56 Type 109.88 5.44 0.04 2 105.85 Constant 110.63 6.18 0.03 1 108.62 Order 112.55 8.10 0.01 4 104.41 Type + order 113.09 8.64 0.00 5 102.89 According to the best fitting model, the DNS for 1.0 closed and open nests decreased as the breeding season 0.9 progressed, but closed nests had higher values (Figure 0.8 1). In the first 10 days of the breeding season, the DNS estimates tended to decrease at a lower rate (closed nests 0.7 = 0.996 to 0.992, open nests = 0.985 to 0.972) than in 0.6 the last 10 days (closed nests = 0.917 to 0.851, open Closed nests 0.5 nests = 0.767 to 0.629; Figure 1). Closed nests had high Open nests estimates of reproductive success early in the season 0.4 1 4 7 1013161922252831343740434649 (69.8%), and values up to 5.3 times lower at the end of Reproductive season (days) the season (13.2%). Reproductive success for open nests FIGURE 1. Daily Nest Survival (DNS) estimates for open and closed ranged from 30.5% at the beginning of the season and nests during the first bree ding season (2012) at Caatinga, Brazil. close to zero at the end (Figure 2). The difference between Results are based on analyses of the best fitting candidate models. nest types ranged from around 56% at breeding season Linear equation of the best model: DNS = 4.286 -0.074 (breeding season) + 1.216 (type of nest). start to 13% at the end. Revista Brasileira de Ornitologia, 24(3), 2016 Daily Nest Survival Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva of candidate models, and the two best models together Closed nests Open nests explained 73% of the variation (Table 2). We present the results of the best model (nests ) for discussion. During the 2013 breeding season 14 nests were successful and 31 were predated. In this analysis the best adjusted model was also that one which considered the quadratic effect on the nest abundance to explain variations in DNS (Table 2). The next model in the adjustment or der (ΔAIC = 7.27), and the null model (ΔAIC = 8.87), had no support beginning middle end for explaining the variations in the data. The best fitted Reproductive season model explained 94% of variance considered by the set FIGURE 2. Reproductive success estimation (%) for open and closed nests according to three nesting start dates during the breeding season of candidate models (Table 2). We used the best model (beginning, middle and end), with a period of 27 days between egg 2 (nest ) to generate the estimates of DNS. laying and fledgling flight. DNS tended to increase during periods of low daily Evaluation of the effect of time-dependent factors nest abundance records. During the 2012 breeding season, was based on 24 and 45 open nests from the 2012 and DNS ranged from 0.743 to 0.946 with 5 to 10 active 2013 breeding seasons, respectively. During the first nests per day being recorded. In the 2013 breeding season breeding season, seven nests were successful and 17 were DNS ranged from 0.831 to 0.952 with 2 to 7 active nests preyed upon. Two candidate models showed substantial per day being recorded (Figure 3). In periods of higher support to explain the variation in DNS estimates, and recorded nest abundance, DNS tended to decrease in the the best model was that one which considered the effects 2012 breeding season, but was more constant in 2013. of the covariate nest abundance (Table 2). The best model During the 2012 breeding season, DNS decreased from was affected by the quadratic effect of nest abundance, 0.969 to 0.919, with 17 to 22 active nests recorded daily, while in the second model (ΔAIC = 0.84), DNS was while in 2013 DNS values oscillated between 0.977 affected by the linear effect of bree ding season. The best and 0.975, with 13 to 18 active nests recorded daily model explained 44% of variance considered by the set (Figure 3). Reproductive success estimates for open nests TABLE 2. Candidate models considered for evaluating the effect of covariates for time-specific variation of DNS (Daily Nest Survival) estimates for open nests during two studied breeding seasons in Caatinga, Brazil. Selection was based on Akaike Information Criterion with correction for small samples (AIC ). The w-AIC is the support of each model in relation to the set of candidate models. K represents the number of parameters of each model. c c Model AIC ΔAIC w-AIC KDeviance c c c 2012 Breeding season Nests 60.64 0.00 0.44 3 54.48 Season 61.48 0.83 0.29 2 57.40 Season 63.07 2.42 0.13 3 56.91 Nests 63.32 2.67 0.11 2 59.24 Constant 66.84 6.20 0.01 1 64.82 2013 Breeding season Nests 134.98 0.00 0.94 3 128.92 Nests 142.25 7.26 0.02 2 138.22 Constant 143.85 8.86 0.01 1 141.84 Season 144.23 9.25 0.00 2 140.20 Season 144.71 9.72 0.00 3 138.65 1.00 1.00 (A) (A) (B (B) 0.95 0.95 0.90 0.90 0.85 0.85 0.80 0.80 0.75 0.75 0.70 0.70 0 5 10 15 20 25 0 5 10 15 20 Nest abundance Nest abundance FIGURE 3. Daily Nest Survival (DNS) estimates for open nests with nest abundance considered (quadratic effect), during the 2012 (A) and 2013 (B) breeding seasons at Caatinga, Brazil. Results are based on the best model from the analysis of candidate models. Linear equation of the best 2 2 models: (A) DNS = -1.928 + 0.715 (nests) -0.023 (nests ) and (B) DNS = 0.841 + 0.403 (nests) -0.014 (nests ). Revista Brasileira de Ornitologia, 24(3), 2016 Reproductive success (%) Daily Nest Survival Daily Nest Survival Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva were low (Figure 4). During the 2012 breeding season frequency may be directly related to density (Gates & reproductive success ranged from very low to almost Gysel 1978, Roos 2002, Aguilar et al. 2008, Paiva 2008, zero (7.4 to 0.01% of successful nests). During the 2013 Dias et al. 2010). breeding season reproductive success declined from Our results have found a different effect to that the beginning and middle of the breeding season, then commonly reported in the literature, and indicate a direct increased again to peak at the end of the season (15.1%). relationship between the abundance of nests and estimates of DNS. In other words, an inverse relationship between 2012 2013 the abundance of nests and their risk of predation. This may have climatic links. The bree ding season in the Caatinga is among the shortest reported for any seasonal Neotropical environment (Cavalcanti 2014), possibly due to the short rainy season and associated period of adequate food availability. In 2013 the breeding season at the current study site lasted only 87 days (active nests) (Cavalcanti 2014). It is possible that this brevity results beginning middle end in an avian breeding season so short, intense, widespread Reproductive season and temporally contiguous as to generate rapid predator FIGURE 4. Reproductive success estimate (%) with open nests at satiation. In such a situation, prey consumption rates Caatinga, Brazil, according to three nest start dates (beginning, middle may depend simply on the intake ability and digestive and end) during the 2012 and 2013 breeding seasons, and with a capacity of individual predators (Jeschke et al. 2002). period of 27 days between egg laying and nestling flight. When satiation is achieved hunting activities decrease, lowering predation rates (Jeschke et al. 2002). According DISCUSSION to this hypothesis, a rapid predator satiation process may result in the inverse relationship between the abundance Predation was the main cause of nest failure during and predation rate of nests, as we observed at this this study. This parallels observations made in Cerrado Caatinga site. We recorded low levels of avian reproductive success, (Carvalho et al. 2007, Medeiros & Marini 2007, Aguilar and a marked variation between the two study years et al. 2008, França & Marini 2009a, Borges & Marini 2010), Amazonia (Oniki 1979, Mullner & Linsenmair (2012, 0.01 to 7% and 2013, 10% to 15%). Reports of 2007) and Atlantic Forest (Duca & Marini 2005, Duca reproductive success for other seasonal Neotropical areas & Marini 2008). In our study closed nests had higher are generally higher than those recorded (Cerrado - Suiriri affinis 32%, Suiriri islerorum 10%, Lopes & Marini success, and this also has been commonly observed in 2005b; Elaenia chiriquensis 33%, Medeiros & Marini both Neotropical (Oniki 1979, Robinson et al. 2000, Duca & Marini 2005, Duca & Marini 2008, Faria et al. 2007; Tyrannus savana 52.5%, Marini et al. 2009a; 2008) and temperate areas (Purcell & Verner 1999). It Elaenia cristata 27.1%, Marini et al. 2009b; Mimus is assumed that closed nests are under lower predation saturninus 54%, Rodrigues 2009). For some species, breeding success values close to those of the current study rates due to the reduced accessibility of nest contents to have been reported (Amazonia - Cercomacra tyrannina predators (Oniki 1979). Our data provide evidence that the characteristic feature of the semiarid Caatinga, with 7.1%, Robinson et al. 2000; Cerrado - Volatinia jacarina high unpredictability in the availability and distribution 4.7%, Carvalho et al. 2007; Cerrado – S. islerorum 16.8 of rainfall (Prado 2003), is not a factor that changes the and 6.7%, França & Marini 2009b). A study in Cerrado has shown that overall bird community breeding success overall Neotropical pattern of high nest predation rates in areas under high human impact (16.6%) may be less on all types of nests. Few studies have considered the processes responsible than those in more natural areas (29.4%) (Borges & for temporal variation in predation in Neotropical bird Marini 2010). We report here the lowest reproductive nests. Results presented here indicate a temporal effect success values so far encountered in the Neotropics, and this may be a consequence of the high levels of human of nest abundance in the Daily Nest Survival. Predator- impact on the study site vegetation, the mosaic nature of prey interactions are commonly considered to be related to density-dependent effects (e.g. Gates & Gysel 1978, the landscape, or the unique nature of Caatinga rainfall Oliveira et al. 2001, Oro et al. 2006), and some of these patterns. While it is difficult to determine which of these is are involved during nest predation (Gates & Gysel 1978, the dominant cause for the low breeding success observed, these results highlight the vulnerability of local Caatinga Bêty et al. 2002, Roos 2002, Paiva 2008). In such studies, bird populations, as heavy nest predation pressure could variation in the risk of nest predation may have arisen from a functional response by predators, so that predation make human-impacted vegetation fragments potentially Revista Brasileira de Ornitologia, 24(3), 2016 Reproductive success (%) Effects of intrinsic and time-specific factors on daily nest survival of bir ds in a semiarid area of South America (Caatinga) Leonardo Fernandes França, Camila Melo da Silva and Luciana Vieira de Paiva Dias, R. I. & Macedo, R. H. 2011. Nest predation versus resources inviable, as either population sources or sinks for the local in a Neotropical passerine: constraint of the food limitation avifauna. hypothesis. Ornis Fennica, 88: 30–39. This study is one of the first to establish t he current Dinsmore, S. J.; White, G. C. & Knopf, F. L. 2002. Advanced patterns of variation in breeding success for Caatinga techniques for modeling avian nest survival. Ecology, 83: 3476– birds. The pronounced i mportance of predation and 3488. Duca, C. & Marini, M. Â. 2005. Temporal variation in the the effect of the type of nest demonstrated by this reproductive success of Cacicus haemorrhous (Linnaeus) (Aves, study show that breeding success for Caatinga birds are Icterinae) in an Atlantic Forest reserve in southeast Brazil. Revista governed by processes similar to those found in other Brasileira de Zoologia, 22: 484–489. Neotropical environments. On the other hand, the local Duca, C. & Marini, M. Â. 2008. Breeding success of Cacicus haemorrhous (Linnaeus) (Aves: Icteridae) in different environments characteristics of inverse dependence between abundance in an Atlantic Forest reserve in southeast Brazil. 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Journal

Ornithology Research – Springer Journals

Published: Sep 1, 2016

Keywords: avian; density-dependence; predation; reproductive success

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