| Autor: |
Pollock HS; Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Champaign, IL 61801., Toms JD; Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.; Canadian Wildlife Service, Environment and Climate Change Canada, Edmonton, AB T6B 1K5, Canada., Tarwater CE; Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071.; Smithsonian Tropical Research Institute, 0843-03092 Balboa, Panama., Benson TJ; Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Champaign, IL 61801.; Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL 61820., Karr JR; School of Aquatic and Fisheries Sciences, University of Washington, Seattle, WA 98915., Brawn JD; Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, Champaign, IL 61801.; Smithsonian Tropical Research Institute, 0843-03092 Balboa, Panama. |
| Abstrakt: |
Long-term studies on the population dynamics of tropical resident birds are few, and it remains poorly understood how their populations have fared in recent decades. Here, we analyzed a 44-y population study of a Neotropical understory bird assemblage from a protected forest reserve in central Panama to determine if and how populations have changed from 1977 to 2020. Using the number of birds captured in mist nets as an index of local abundance, we estimated trends over time for a diverse suite of 57 resident species that comprised a broad range of ecological and behavioral traits. Estimated abundances of 40 (∼70%) species declined over the sampling period, whereas only 2 increased. Furthermore, declines were severe: 35 of the 40 declining species exhibited large proportional losses in estimated abundance, amounting to ≥50% of their initial estimated abundances. Declines were largely independent of ecology (i.e., body mass, foraging guild, or initial abundance) or phylogenetic affiliation. These widespread, severe declines are particularly alarming, given that they occurred in a relatively large (∼22,000-ha) forested area in the absence of local fragmentation or recent land-use change. Our findings provide robust evidence of tropical bird declines in intact forests and bolster a large body of literature from temperate regions suggesting that bird populations may be declining at a global scale. Identifying the ecological mechanisms underlying these declines should be an urgent conservation priority. |
