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/lp/springer-journals/discolored-and-worn-out-plumage-in-juvenile-magellanic-penguins-4ZEd7g85Yo
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- Springer Journals
- Copyright
- Copyright © Sociedade Brasileira de Ornitologia 2018
- eISSN
- 2178-7875
- DOI
- 10.1007/bf03544430
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Abstract
Revista Brasileira de Ornitologia 26(3): 202–206. ARTICLE September 2018 Discolored and worn-out plumage in juvenile Magellanic Penguins (Spheniscus magellanicus) found ashore in southeast and northeast Brazil 1,2,5 3,4 3 3 Ralph Eric Thijl Vanstreels , Renata Hurtado , Leandro Egert , Luis Felipe Mayorga , 3 1,2 Renata Cristina Campos Bhering & Pierre A. Pistorius Marine Apex Predator Research Unit, Institute for Coastal and Marine Research, Nelson Mandela University, Port Elizabeth, South Africa. DST/NRF Centre of Excellence at the Percy FitzPatrick Institute for African Ornithology, Department of Zoology, Nelson Mandela University, Port Elizabeth, South Africa. Institute of Research and Rehabilitation of Marine Animals (IPRAM), Cariacica, Brazil. Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa. Corresponding author email: ralph_vanstreels@yahoo.com.br Received on 19 January 2018. Accepted on 10 May 2018. ABSTRACT: Magellanic Penguins (Spheniscus magellanicus) are common winter visitors of the Brazilian continental shelf. In this study we report the occurrence of discolored and worn-out plumage in juvenile Magellanic Penguins washed ashore during summer on the southeast and northeast coast of Brazil. In the affected in dividuals, the areas of the plumage that would normally be black or dark grey were discolored to tones ranging from brown to cream-white, especially on the head and dorsum. Upon close examination, the feathers were often brittle and appeared “old” and worn-out, at times leading to irregular and asymmetric patches of feather-loss in the lower back. We propose five factors that could be involved in causing this condition: (a) molt skipping, (b) sun exposure, (c) malnutrition, (d) insufficient preening, and (e) chewing lice. KEY-WORDS: chromatic aberration, feather-loss, molt, plumage, seabird, Spheniscus demersus. INTRODUCTION the annual cycle of penguins (Kemper & Roux 2005, Wolfaardt et al. 2009). Magellanic Penguins (Spheniscus magellanicus) are native In March 2010, Petry et al. (2017) photographed a juvenile Magellanic Penguin with light brown plumage to Argentina, Chile and the Falkland/Malvinas Islands that had been found ashore on the coast of Rio Grande and are common visitors of the Uruguayan and Brazilian continental shelves during austral winter (Stokes et al. do Sul state, Brazil. The authors interpreted t his aberrant 2014). Magellanic Penguins will normally remain at sea plumage color as corresponding to the first case of a brown during winter migration (Pütz et al. 2007), however a mutation in Magellanic Penguins. Brown mutation is a color aberration related to a qualitative reduction of variable number of individuals, predominantly juveniles eumelanin (e.g., incomplete synthesis or oxidation), and that are in poor body condition, have previously been reported to wash ashore on the Brazilian coast (García- as a result the black areas of the plumage shift to a light Borboroglu et al. 2010, Rodrigues et al. 2010, Stokes brown tone (van Grouw 2013). In this study we report et al. 2014). As occurs in other penguins, Magellanic the presence of juvenile Magellanic Penguins with varying levels of plumage discoloration and feather-loss, some of Penguins undergo a rapid molt in which all their feathers which closely resemble the brown-plumaged penguin are replaced over a period of 2–4 weeks (Williams 1995). During the molt, which in the Magellanic Penguin usually photographed by Petry et al. (2017), however we propose occurs between February and April, their plumage loses a distinct etiology for this phenomenon. its waterproofing and as a result the penguins have to remain on land, fasting (Boersma et al. 2013b). Molting METHODS is therefore an energetically-demanding process that has to be preceded by a period of fattening (with an increase of up to 50–70% in body weight) (Williams 1995), and The Institute of Resear ch and Rehabilitation of Marine preparing for molt can be one of the key factors driving Animals (Instituto de Pesquisa e Reabilitação de Animais Revista Brasileira de Ornitologia 26(3): 2018 Discolored and worn-out plumage in Magellanic Penguins Vanstreels et al. Marinhos – IPRAM) is a non-profit organization based the juvenile penguins admitted from October to March o o in Cariacica (20 19'54''S; 40 21'38''W), Espírito Santo every year also frequently present a discolored and worn- state, that rescues and rehabilitates marine animals found out plumage (Fig. 1). ashore along the coast of southern Bahia (northeast region), Espírito Santo and northern Rio de Janeiro states (southeast region), Brazil. An average of 110 Magellanic RESULTS AND DISCUSSION Penguins are admitted for rehabilitation per year, a majority of which are juveniles (98%) that are severely From a sample of 33 penguins admitted from the northern debilitated (lethargic/comatose, severely emaciated, coast of Rio de Janeiro between October and December dehydrated, anemic and hypoglycemic). 2015, 15 penguins (45%) had plumage discoloration and/ Most penguins (78%) are admitted from July or patches of feather-loss (see Fig. 1B). In these cases, the to September, whereas a smaller proportion (22%) is areas of the plumage that would normally be black or dark admitted from October to June. In addition to the general grey are discolored to tones ranging from brown to cream- state of malnutrition and debilitation that is common to white. The discoloration is usually more pronounced on nearly all juvenile penguins found ashore in this region, the head and dorsum. There are cases, however, where the Figure 1. Discolored and worn-out plumage in juvenile Magellanic Penguins (Spheniscus magellanicus) admitted for rehabilitation along the coast of southeast and northeast Brazil. (A & B) examples of the large numbers of juvenile Magellanic Penguins with worn- out plumage; (C–E) a particularly extreme example of plumage discoloration; (F–H) examples of the different patterns of plumage wear, discoloration and feather-loss and feather replacement on the lower back. Photographs taken in Jan 2013 (C–E), Dec 2013 (A), and Dec 2015 (B, F–H). Photo authors: Renata Hurtado/IPRAM (A, B, F, G, H); Luís F. Mayorga/IPRAM (C, D, E). Revista Brasileira de Ornitologia 26(3): 2018 Discolored and worn-out plumage in Magellanic Penguins Vanstreels et al. discoloration is evenly distributed and all the feathers that Despite their generally poor health status would be black have a light brown color instead (Fig. 2A). (dehydration, malnutrition, lethargy) and the poor Upon close examination, the feathers are often brittle and condition of their plumage, the penguins with discolored appear “old” and worn-out; in some areas, the barbules plumage and feather-loss usually respond well to may be irregularly broken and the feather shaft is exposed. rehabilitation. After a few weeks under care and receiving In many cases, there are irregular and asymmetric patches adequate nutrition (fresh fish and mineral/vitamin of feather-loss, especially in the lower back. The loss of supplementation) and deworming medicine, these birds feathers may lead the skin to be entirely exposed (e.g. Figs. will usually initiate the molt. In a few cases, the penguins 1E & 1G), but oftentimes a downy plumage grows to with discolored plumage are not debilitated upon form a furry coat in areas where the normal plumage was admission and instead show signs of pre-molt (good body lost (e.g. Figs. 1F & 1H). condition, flipper edema, lethargy). In all cases admitted at IPRAM, when penguins with discolored plumaged completed the molt they emerged with an entirely normal black-and-white adult plumage (Fig. 2). If this plumage discoloration had a genetic basis it would be expected that the brown/cream-white color would be maintained even after molt, and we therefore consider that factors other than genetic mutations must be at play. Because the plumage discoloration we observed in juvenile Magellanic Penguins is invariably accompanied by other signs of poor plumage quality (e.g., worn-out appearance of feathers, patches of feather-loss) and appears to be seasonally distributed, we suggest it is primarily related to feather wear. We propose five factors that could synergize to cause this condition: (a) molt skipping, (b) sun exposure, (c) malnutrition, (d) insufficient preening, and (e) chewing lice. Juvenile African Penguins (Spheniscus demersus) with a light brown and worn-out plumage (Fig. 3) are routinely admitted during summer months at the South African Foundation for the Conservation of Coastal Birds (SANCCOB), in South Africa; these individuals will also invariably emerge with a normal black-and-white adult plumage after molt (R. Hurtado, pers. obs.). In a study on the molting ecology of African Penguins in Namibia, Kemper & Roux (2005) found that some juvenile African Penguins may skip the first molting season and retain Figure 2. Example of an individual that was admitted with a brown juvenile plumage, underwent molt and emerged with normal adult plumage. (A) bird is lethargic and dehydrated upon admission, with a worn-out pale brown plumage (18 Mar Figure 3. A juvenile African Penguin (Spheniscus demersus) with 2017); (B) bird recovers gradually and undergoes molt (24 Mar a discolored and worn-out plumage admitted for rehabilitation 2017); (C) bird is fully recovered and completed the molt to at the Southern African Foundation for the Conservation of a normal adult plumage (19 Apr 2017). Photo author: Luís F. Coastal Birds, South Africa (Dec 2017). Photo author: Renata Mayorga/IPRAM. Hurtado/SANCCOB. Revista Brasileira de Ornitologia 26(3): 2018 Discolored and worn-out plumage in Magellanic Penguins Vanstreels et al. their juvenile plumage until 20–22 months of age. These wear. Additionally, it is known that penguins adjust individuals are referred to as “skippers”, and their plumage their foraging schedule in response to prey availability, is badly worn and not fully waterproof, jeopardizing and in extreme circumstances of shortage of prey some their ability to forage in cold waters. Juvenile Magellanic individuals may forage up to 15 h per day, i.e. non-stop Penguins have been occasionally seen in the coastal waters foraging from dawn to dusk (Culik et al. 2000). In these of Rio de Janeiro during summer months (R. Hurtado, instances, the increased time spent foraging will certainly pers. obs.), possibly in an attempt to forage in the Cabo come at the cost of a decreased time preening, and feather Frio upwelling waters. Considering that the nearest quality is likely to deteriorate as a result. Furthermore, it breeding colony of Magellanic Penguins is almost 3000 is also possible that these juvenile individuals had received km away from the coast of Rio de Janeiro (Boersma et al. suboptimal nutrition as chicks, which could have resulted 2013b), it is reasonable to suspect that these individuals in poor quality feathers that were more susceptible to might not return to their colonies in time to undergo discoloration and wear. molt in February/March. If this is the case, the plumage Chewing lice (Austrogoniodes sp.) are common in of these individuals can be expected to be considerably juvenile Magellanic Penguins on the southeast coast of worn-out by the summer of the subsequent year. We Brazil, and in some instances they can be found in >95% therefore suspect that the cases of plumage discoloration of carcasses washed ashore (R.E.T. Vanstreels, unpub. and feather-loss we documented in juvenile Magellanic data). Chewing lice can cause direct damage to the Penguins in this study represents a situation comparable feathers and accelerate their wear (Kose et al. 1999), and to the African Penguin skippers, i.e. extreme instances of can also lead to feather damage indirectly by inducing feather wear related to juvenile Magellanic Penguins that feather-damaging behavior (van Zeeland & Schoemaker skipped their first-year molt. 2014). While it is unlikely that chewing lice cause Considering that the body parts that are usually plumage discoloration, it seems plausible that they might most intensely discolored are those that stay outside of have contributed directly or indirectly to the patches of the water when a penguin swims (see Fig. 1A), prolonged feather-loss reported in this study. exposure to the sun could also play a role. For instance, It is worth noting that Traisnel et al. (2018) the Galapagos Penguin (Spheniscus mendiculus) is the documented an adult African Penguin whose black northernmost-breeding penguin species and its gray- plumage had been uniformly replaced by a light brown black plumage is known to gradually progress to a brown tone; this case was considered consistent with brown tone during the months following molt (Boersma et al. mutation, and the dorsal plumage of that individual 2013a). This species is unique among penguins in that was also heavily bleached out. This suggests that in cases its adults molt twice per year (Boersma et al. 2013a), of brown mutation, the decreased oxidization of the possibly an adaptation to the intense feather wear caused eumelanin might also make the plumage more susceptible by high solar irradiance near the Equator. Considering to sun-mediated discoloration. In the case of the juvenile that brown plumage discoloration is relatively common in Magellanic Penguins in this study, it is plausible that the juvenile Magellanic Penguins in northeast and southeast eumelanin in the feathers of juveniles may be less oxidized Brazil whereas it appears to be rare in individuals found that in the feathers of adults, resulting in an increased ashore in southern Brazil (L. Bugoni, pers. comm.), it is susceptibility to discoloration. possible that plumage discoloration is more frequent in In conclusion, juvenile Magellanic Penguins found individuals wintering at lower latitudes is related to the ashore in southeast and northeast Brazil during summer Equatorward increase in solar irradiance. months frequently present a discolored and worn-out The oily secretion produced by the uropygial plumage. It seems unlikely that genetic mutations are gland plays an important role in reducing feather wear, the cause of these plumage abnormalities. We propose, inhibiting chewing lice and feather-degrading bacteria instead, that the plumage abnormalities we documented (Shawkey et al. 2003, Moreno-Rueda 2010, 2011). are the result of feather wear due to a combination of Boersma et al. (2013a) speculated that the plumage factors related to the challenges experienced by these of Galapagos Penguins becomes brown in the period birds during their first-year migration. preceding molt because the penguins stop oiling their feathers. Juvenile Magellanic Penguins admitted for ACKNOWLEDGEMENTS rehabilitation in northeast and southeast Brazil have undergone extended periods of malnutrition, as evidenced by the generally poor body condition and health status. It We are grateful to all the volunteers, interns and staff from is therefore possible that malnourished juvenile penguins IPRAM and SANCCOB. 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Journal
Ornithology Research – Springer Journals
Published: Sep 1, 2018
Keywords: chromatic aberration; feather-loss; molt; plumage; seabird; Spheniscus demersus