Birds and cavities: key interactions to manage logged forests

Comparing interaction networks between cavity-nesting birds and trees, in undisturbed sites (US) and logged sites (LS), is useful for management guidelines of the latter. We present results of an ongoing monitoring of three US’s and four LS’s in piedmont forests of Salta and Jujuy. We recorded 229 interactions among 14 tree species and 20 bird species (five excavators, and 15 non- excavators) at UD’s, and 50 interactions between eight tree species and 14 bird species (four excavators and 10 non-excavators) at LS’s. Non-excavators mostly used decay-formed cavities; woodpecker-excavated cavities were more often used at LS’s (25% of non-excavator interactions, n=24) than at US’s (10%, n=68). Key tree species based on Importance and Strength indices were Calycophyllum multiflorum, Anadenanthera colubrina and «snags» (dead trees) at US’s, and snags, A. colubrina and Astronium urundeuvaat LS’s. Simulated extinction of key tree species disappeared 32% of bird species at US’s, and 46% at LS’s. There were three interaction modules at US’s; a fourth module of non-excavating birds with decay-formed cavities in snags was added at LS’s. Other parameters were similar in SSD vs. SAF: connectance 0.15 vs. 0.16; interaction dominance 0.135 vs. 0.140; and interaction evenness 0.957 vs. 0.962. The exposed differences suggest a shortage of decay-formed cavities in living trees at LS’s, possibly due to the high extraction of C. multiflorum.