Bird Occupancy of a Neotropical Forest Fragment Is Mostly Stable over 17 Years but Influenced by Forest Age

Gabriel Augusto Leite,W. Douglas Robinson,T. Mitchell Aide,Marconi Campos-Cerqueira

doi:10.3390/d13020050

Abstract

The effects of forest degradation, fragmentation, and climate change occur over long time periods, yet relatively few data are available to evaluate the long-term effects of these disturbances on tropical species occurrence. Here, we quantified changes in occupancy of 50 bird species over 17 years on Barro Colorado Island (BCI), Panama, a model system for the long-term effects of habitat fragmentation. The historical data set (2002–2005) was based on point counts, whereas the contemporary data set (2018) was based on acoustic monitoring. For most species, there was no significant change in occupancy; however, the occupancy of four species (Tinamus major, Polioptila plumbea, Myiarchus tuberculifer, and Ceratopipra mentalis) increased significantly, and the occupancy of three species (Saltator grossus, Melanerpes pucherani, and Cyanoloxia cyanoides) decreased significantly. Forest age explained the majority of occupancy variation and affected the occupancy of more bird species than survey period or elevation. Approximately 50% of the species seem to favor old-growth forest, and 15 species (30%) had a significantly higher occupancy in old-growth forest sites. Elevation had no significant impact on the occupancy of the majority of bird species. Although BCI has been a protected reserve for approximately 100 years, land-use legacies (i.e., forest age) continue to influence bird distribution.

Highlights

Changes in community composition continue long after initial isolation of habitat remnants [1]
Detection probability varied greatly among species, and more than half of the species had greater detectability in one particular period (Figure 2, Table S3), suggesting that failures to account for detection probability could negatively affect occupancy estimates and our inference regarding the effect of Era on species occupancy
Of the 50 species included in the occupancy models, only three species had significantly higher detectability in the historical period, whereas 22 species had similar detectability among historical and current periods, and 25 species had significantly higher detectability in the current period (Figure 2, Table S4)

Summary

Introduction

Changes in community composition continue long after initial isolation of habitat remnants [1]. A naïve expectation is that remnants with mature forest surrounded by stable habitat matrix characteristics may be less likely to show evidence of community change or species’ abundances through time. In undisturbed forests in the central Amazon, terrestrial and near-ground insectivorous bird species appear to be the most vulnerable, whereas some frugivorous species may increase in abundance [9]. Few long-term studies of population fluctuations exist for Neotropical sites, but the few available ones suggest fairly stable bird populations, especially in older forests [11]. Characterizing such long-term community shifts and the associated changes in population sizes of vulnerable species is needed for effective conservation and management

Methods

Results

Discussion

Conclusion