Opportunistic predation on birds trapped in mist nets in two areas in the Atlantic Forest of southeastern Brazil

ABSTRACT

Mist netting is the most popular method for capturing birds, but it can increase the predation rates of individuals trapped in the nets. From 2008 to 2017, we recorded eight instances of opportunistic bird predation from mist nets (MNs) in a matrix mixing restored forest and fragments of semideciduous seasonal forest in southeastern Brazil, three times (37.5%) by exotic primates and five times (62.5%) by birds of prey. Overall predation rates (1.17–1.20%) at these two sites were considered high but were lower than in other Brazilian studies. Placing MNs near the edges of forest fragments may have allowed attacks by either forest predators or marmosets, which are exotic edge species. Some previously described precautions may decrease the predation rates of birds in MNs, such as shorter observation intervals, greater attention to given site selection and maintaining a safe distance between the MNs and the ground.

RESUMO

Redes-de-neblina é o método de captura de aves mais popular entre os pesquisadores; todavia pode aumentar as taxas de predação dos espécimes capturados. De 2008 a 2017, registramos oito predações oportunistas de aves em redes-de-neblina; sendo três delas (37.5%) por primatas exóticos e cinco (62.5%) por rapinantes. As taxas de predação (1.17-1.20%) das duas áreas de estudo foram consideradas altas, mas menores que aquelas registradas em outros estudos realizados no Brasil. Instalar as MN próximo às bordas de fragmentos florestais pode permitir ataques tanto de predadores florestais quanto de saguis exóticos de borda de mata. Algumas precauções descritas anteriormente podem diminuir as taxas de predação de aves em MN, como redução nos intervalos de revisão, atenção à localização e manutenção da distância segura do solo.

KEYWORDS:

• Trophic interaction
• forest edge
• raptors
• marmosets
• exotic species

Acknowledgments

We are grateful to the SOS Mata Atlântica Foundation (SOSMA), Heineken Brasil® for logistical and financial support and Division of Fauna and to the Municipality of São Paulo for supporting our research carried out in this municipality; we also thank the staff of SOSMA Centro de Experimentos Florestais (Aretha Medina, Rafael Fernandes, Ana Paula, Kelly De Marchi, Roberto Cândido, Cícero and Wilson) for cooperation and incentive to research. We also thank Mr. William Hering for the logistical support and all the special treatment given to the fauna of Fazenda Castanheiras. Finally, we thank the Instituto Chico Mendes de Conservação da Biodiversidade for permission for mist netting (SISBIO: 53122-1; Municipality of São Paulo) for access to the studied areas (Municipal Permit 40/2014), and CEMAVE/ICMBio for bird banding (Permit 1267/12).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work received financial support from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) through grants to PGAB [104555/2017-3] and DJM [142103/2015-2]; and logistical support by SOS Mata Atlântica Foundation/Heineken Brasil®.