Availability of tree cavities and abundance of cavity nesting birds: recommendations for sustainable forest management in Northwestern Argentina

Forestry management changes forest structure and composition and it has been suggested that cavity nesting birds are particularly sensitive to these changes. The aim of this study is to determine if cavity nesting birds using cavities present in the forest (secondary cavity-nesters) change their abundance and to understand the relationship between this group of species and cavity availabilityin piedmont Yungas forest being logged in northwestern Argentina. During two breeding seasons we conducted 30 point counts of 10 minutes length and 50 meter fixed-radius across three reference sites and three sites with forestry management in order to determine bird abundance. Additionally, we selected 10 to 20 circular plots to evaluate density of trees with cavities. We found higher abundance of secondary users in sites without forestry management compared to those being logged (6,41 ± 4,16 vs. 3,36 ± 2,73; U Mann-Whitney = 22771 – p= <0,0001). Cavity density was also higher in sites without forestry management (14,88 ± 7,50 vs. 6,20 ± 4,05; U Mann-Whitney = 1147,50 – p= <0,0001). Secondary user abundance was positively correlated with cavity density (R²= 0,78 – p= 0,003). The relationship between secondary users and cavity density suggests the need for maintaining these cavities available in sites with forestry management.