Bird assemblage mist-netted in an Atlantic Forest area: a comparison between vertically-mobile and ground-level nets

Area of Science:

• Ornithology
• Ecology
• Biodiversity Research

Background:

• Mist nets are commonly used for bird capture but typically deployed at low heights.
• Sampling birds exclusively at ground-level may not fully represent the entire avian community structure.

Purpose of the Study:

• To compare bird species richness, composition, abundance, and trophic structure using conventional ground-level nets versus vertically-mobile elevated nets.
• To assess the impact of sampling height on the diagnosis of avian assemblages in the Atlantic Forest.

Main Methods:

• Employed two mist-netting methods: conventional ground-level nets (0-2.4 m) and vertically-mobile elevated nets (0-17 m).
• Standardized captures to 290 birds for comparative analysis of species richness, composition, and trophic structure.
• Utilized Chi-squared tests to identify significant differences in capture frequencies between methods.

Main Results:

• Significant differences in capture frequencies were observed for approximately 20% of species between the two methods.
• Ground-level nets underestimated frugivores and nectarivores while overestimating Suboscine insectivores compared to elevated nets.
• The two sampling methods captured distinct bird assemblages, indicating method-dependent biases.

Conclusions:

• Different mist-netting heights yield significantly different assessments of avian assemblages.
• Incorporating sampling of upper forest strata with vertically-mobile nets is crucial for a more accurate representation of Atlantic Forest avifauna.
• Researchers should consider employing varied sampling heights to avoid biases in biodiversity assessments.