Foraging behavior and diet of the vulnerable Cinereous Warbling-finch Poospiza cinerea (Aves, Emberizidae)

Abstract

The Cinereous Warbling-finch Poospiza cinerea is a globally vulnerable Emberizidae passerine, patchily distributed and rare in the open savannah of central South America. Attributes of rare species include niche specificity such as feeding habits. To verify possible niche specialization in this species we aimed to describe its foraging habits related to substrate use, foraging and substrate height, attack maneuvers, and consumed food items. We monitored two groups at two study sites and sampled foraging events with intervals of 15 minutes. The substrates used in greater frequency were foliage and reproductive organs. Foraging and substrate height varied widely with study area. The attack maneuver adopted in greater frequency was glean. Most food items attacked were small invertebrates. Big invertebrates included Lepidoptera, Hemiptera, Coleoptera, Hymenoptera and Orthoptera. Poospiza cinerea was also recorded foraging in mixed bird flocks with seven other species. The generalist foraging behavior of the species cannot be associate to its rarity. Keywords: attack maneuver, feeding behavior, niche specificity, rarity, substrate choice. Comportamento de forrageamento e dieta do vulnerável capacetinho-do-ocodo-pau Poospiza cinerea (Aves, Emberizidae)Resumo O capacetinho-do-oco-do-pau Poospiza cinerea é um passeriforme da família Emberizidae globalmente vulnerável, irregularmente distribuído e raro no Cerrado do centro da América do Sul. Atributos de espécies raras incluem especificidades de nicho tais como hábitos de forrageamento. Para verificar possível especialização de nicho dessa espécie, buscamos descrever seu comportamento de forrageamento relacionado a uso de substrato, altura de forrageamento e do substrato, manobras de ataque e itens alimentares consumidos. Nós monitoramos dois grupos em duas áreas de estudo e amostramos eventos de forrageamento com intervalos de 15 minutos. Os substratos utilizados em maior frequência foram folhagem e órgãos reprodutivos. Alturas de forrageamento e dos substratos variaram amplamente com a área de estudo. A manobra de ataque adotada em maior frequência foi respigar. A maioria dos itens alimentares foi pequenos invertebrados. Grandes invertebrados incluíram Lepidoptera,

New insights on the rarity of the vulnerable Cinereous Warbling-finch (Aves, Emberizidae) based on density, home range, and habitat selection

“…In summary, the evidences are as follows: (1) our analyses indicate that P. cinerea has some flexibility in habitat use and selection, from natural open cerrado habitats to exotic tall urban tree vegetation, while we first described its nest at a roadside at another paper (Wischhoff et al, 2012); (2) the PSC group has a patchy home range with intensive use of woodland edges; (3) the few existent records of P. cinerea are frequently in edges between natural and modified environments (Simon et al, 1999;Ribon, 2002;Lopes et al, 2010); (4) this species is very similar to P. melanoleuca, which is a common and broadly distributed species. Thus, here we suggest that it is unlikely that P. cinerea is scarce owing to habitat degradation, as previously put forward by Ridgely and Tudor (1989).…”

“…Avoidance of urban open areas, lawns, and erosions were expected, since the species forages in vegetation cover and rarely comes down to the ground (Wischhoff et al, 2015). In the ABV group, on the other hand, the selection of tall and medium sized vegetation structure did not achieve statistical relevance.…”

“…It has been suggested that P. cinerea does not have considerable niche specificity in its foraging behavior nor in its diet (Wischhoff et al, 2015). Thus, if particular habitat specificity occurs, it should happen at other scales of habitat selection or niche constraint.…”

“…Records of this species are scarce in literature, limited to few individuals per site and isolated in time (mainly Ridgely and Tudor, 1989;Stotz et al, 1996;Simon et al, 1999;Vasconcelos et al, 1999, Ribon, 2002Vasconcelos and D'angelo Neto, 2007;Lopes et al 2010;Rodrigues et al, 2011;Rodrigues, 2012, 2013;Wischhoff et al, 2012). In fact, P. cinerea is poorly known, having a large gap in its basic biology information (Wischhoff et al, 2012), also being considered as data deficient in the Brazilian red list (Machado, 2005).…”

“…In fact, P. cinerea is poorly known, having a large gap in its basic biology information (Wischhoff et al, 2012), also being considered as data deficient in the Brazilian red list (Machado, 2005).…”