Forest Fragmentation and Bird Extinctions: San Antonio Eighty Years Later

Abstract

We report on the extent of bird extinctions at San Antoni¢~ a fragmented cioud forest site in the western Andes of Colombi~ for which surveys dating back to 1911 and 1959 are available. In 1911 forest bird species were present in San Antonio. Twenty-four species had disappeared by 1959, and since then 16 more species have gone locally extincg for a total of 40 species or 31% of the original avifaumt We analyzed patterns of extinction in relation to geographic distribution and foraging guild~ We found that in this montane assemblag~ being at the limits of the altitudinal distribution was the main correlate of extinction; 3 7% of the extinct species were at the upper limit of their altitudinal distribution We also found that the most vulnerable guilds were the understory insectivores and the large canopy frugivorex Our study illustrates the extent of bird extinctions that are currently undocumented in the highly fragmented forests of the northern Ande~ where the absence of baseline information on the fauna of unaltered forests is a limiting factor for the development of conservation and management planx We stress the need to establish data bases and long-term monitoring projects for the Andean fauna * Present address. NYZS The Wildlife Conservation Society, Apartado 1845, Calg Colombia

Leucism in Akodon affinis (Allen, 1912) (Rodentia: Cricetidae)

“…The dorsum was the part where most individuals Considering the effects of geographic isolation in the emergence of recessive traits (e. g., bottleneck effect; Bensch et al 2000;Lopucki and Mróz 2010), our findings suggest that some populations of A. affinis might be experiencing inbreeding due to either the discontinuous distribution of this species (Roach 2016) or to habitat fragmentation in the Colombian Andes (Kattan et al 1994;Kattan and Alvarez-López 1996). According to the International Union for Conservation of Nature (IUCN), A. affinis is listed as Least Concern since a large population is presumed from its wide overall distribution range (Roach 2016).…”

Museum collections indicate bird defaunation in a biodiversity hotspot

“…Pre-and post-isolation comparisons of tropical forests show the percentage of extinct species varies according to the time lag between isolation. It varies from 49% in a 4-ha fragment in Singapore over 100 years (Sodhi et al 2005) to ca 30% after 50-90 years in Colombian forests (Kattan et al 1994, Renfijo 1999 and Barro Colorado Island, Panama (Robinson 1999). For the Atlantic Forest, Aleixo & Vielliard (1995) noted that 54% of the forest avifauna of an isolated 251 ha southeastern Brazilian remnant was extinct after a 15-year interval.…”

“…These are from little-surveyed sites at time lags of: 200 years in eastern Amazonia (Moura et al 2014), 167 years in southwestern Amazonia (Silveira & D'horta, 2002), 130 years in eastern Brazil (Christiansen & Pitter 1997) and 100 years in Singapore (Sodhi et al 2005). There are also examples of less than a century separating surveys, such as Barro Colorado Island, Panama (85 years, Robinson 1999), San Antonio, Colombia (80 years, Kattan et al 1994), and the Viçosa region, Brazil (70 years, Ribon et al 2003).…”

Bird Abundances in Primary and Secondary Growths in Papua New Guinea: A Preliminary Assessment

“…All detected birds (both seen and heard) were specified and recorded into the following meter classes: 0-20 and 20-50 meters. Point-count censuses were carried out twice a day along the same transects as the line method [13]. The survey at one point lasted 10 minutes and all detected birds were recorded similarly as in line transect (with the same distance classes).…”