Vol.:(0123456789) 1 3 Polar Biology https://doi.org/10.1007/s00300-020-02757-5 SHORT NOTE Coprophagic behaviour of southern giant petrels (Macronectes giganteus) during breeding period Denyelle Hennayra Corá 1  · Júlia Victória Grohmann Finger 2  · Lucas Krüger 3 Received: 27 February 2020 / Revised: 21 September 2020 / Accepted: 25 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Southern giant petrels (Macronectes giganteus) are opportunistic generalists whose feeding strategies include hunting, scavenging and fshing. While seals are important for southern giant petrels as a source of carrion, we documented that live seals also provide feeding opportunities for southern giant petrels. We tracked breeding southern giant petrels from Harmony Point, Antarctica, during incubation and chick rearing with solar-powered GPS-UHF devices. Tracking results showed that animals often visited confrmed haul-out sites of seals, mainly Weddell seals (Leptonychotes weddellii). Feeding on seal faeces was confrmed by direct observation. Southern giant petrels were more likely to visit haul-out sites during incubation than during chick-rearing. This behaviour suggests that the birds fed on seal faeces mainly when fasting, which could last as long as 15 days. Seal faeces could be a resource consumed to quickly recover from the fast before leaving for a longer trip. Keywords Antarctica · coprophagy · diet · foraging Introduction Breeding is an energetically demanding activity during which seabirds invest great efort in successfully raising a chick (Markones et al. 2009). Scavenging on fur seal (Arc- tocephalus gazella), Weddell seal (Leptonychotes weddel- lii) and southern elephant seal (Mirounga leonina) carcasses and placentas provides an important source of food during breeding for giant petrels (Macronectes spp.), especially during the post-hatching period (Hunter 1984; de Bruyn et al. 2007). Carcasses also play an important role in the growth and survival of chicks due to their high energetic and nutritional value (de Bruyn et al. 2007). However, living seals can also provide feeding resources for giant petrels. Casaux et al. (1997) briefy described southern giant petrels (M. giganteus) gathering around hauled-out Weddell seals at Harmony Point (Nelson Island, Maritime Antarctic Pen- insula) to feed upon faeces and regurgitations. They sug- gested that this source of food should be further inspected, as many diet items recorded for southern giant petrels could have been consumed through scavenging on Weddell seal scat and vomit. In this study, we quantifed the incursions of southern giant petrels tracked with GPS to areas where Weddell and elephant seals haul out to rest or moult at Har- mony Point and showed that breeding southern giant petrels frequently feed on seal faeces. We thus provide evidence that coprophagy is a common behaviour for Southern giant petrels in the studied population. We also discuss possible causes and consequences of this behaviour. Materials and methods We monitored feeding behaviour and movements of breed- ing southern giant petrels from a population breeding at Harmony Point (Fig. 1a). The area holds a large southern giant petrel population of ca. 480 breeding pairs (Krüger 2019). While Weddell and elephant seals haul out at Harmony Point throughout the warm season (October to February), there is no recent local evidence of breeding behaviour by either seal species [although three female * Lucas Krüger lkruger@inach.cl 1 Universidade Comunitária da Região de Chapecó, Curso de Ciências Biológicas, Servidão Anjo da Guarda, 295-D, Chapecó, SC, Brazil 2 Laboratório de Ornitologia e Animais Marinhos, Universidade do Vale do Rio dos Sinos, Av. Unisinos, 950, São Leopoldo, RS, Brazil 3 Instituto Antártico Chileno, Plaza Muñoz Gamero, 1055 Punta Arenas, Chile