Energy flux, body size and density in relation to bird species richness along an elevational gradient in Taiwan

Abstract

Aim To examine the species richness of breeding birds along a local elevational gradient and to test the following assumptions of the energy limitation hypothesis:(1) the energy flux through birds is positively correlated with above-ground net primary productivity, (2) bird density is positively correlated with total energy flux, and (3) bird species richness is positively correlated with bird density.Location An elevational gradient from 1400 to 3700 m on Mt. Yushan, the highest mountain in Taiwan (23 ° 28 ′ 30 ″ N, 120 ° 54 ′ 00 ″ E), with a peak of 3952 m a.s.l. MethodsWe established 50 sampling stations along the elevational gradient. From March to July 1992, we estimated the density of each bird species using the variable circular-plot method. Above-ground net primary productivity was modelled using monthly averages from weather data for the years 1961-90. ResultsBird species richness had a hump-shaped relationship with elevation and with net primary productivity. Bird energy flux was positively correlated with net primary productivity and bird species richness was positively correlated with bird density. The relationship between bird density and energy flux was hump-shaped, which does not support one assumption of the energy limitation hypothesis. Main conclusionsThe results supported two essential assumptions of the energy limitation hypothesis. However, when energy availability exceeded a certain level, it could decrease species richness by increasing individual energy consumption, which reduced bird density. Thus, energy availability is a primary factor influencing bird species richness at this scale, but other factors, such as body size, could also play important roles.

Bird community structure in natural and urbanized habitats along an altitudinal gradient in Pauri district (Garhwal Himalaya) of Uttarakhand state, India

“…The pattern of the avian community of the present study varies from that reported by many previous studies conducted on bird species richness along altitudinal gradients mostly in temperate regions. Most such studies have found the highest species richness at low elevation such as in rain forest of eastern Andes Peru (Terborgh 1971;Terborgh & Weske 1975) or mid elevation such as in Peruvian Andes (Rahbek 1995(Rahbek , 2005, Madagascan rain forest (Colwell & Lees 2000), Bolwian Andes South American Forest (Kessler et al 2001), Columbian Andes forest (Kattan & Franco 2004), urban/subtropical to subarctic forest in Taiwan (Lee et al 2004;Ding et al 2005). In the present study the higher BSD and BSR observed in high altitude areas may be connected to the higher plant diversity.…”

The Taiwan Firecrest (Regulus goodfellowi) belongs to the Goldcrest assemblage (Regulus regulus s. l.): evidence from mitochondrial DNA and the territorial song of the Regulidae

“…On Taiwan it is a common breeder in the coniferous forests of the central mountain ridges at altitudes from roughly 2,000 to 3,700 m asl. The species is fairly common in stands dominated by Abies kawakamii, Tsuga formosana, and Picea morrisonicola but also inhabits coniferous and broad-leaved mixed forests, and only during the winter season do populations move vertically to lower elevations (Ding et al 1997(Ding et al , 2005; Shiu and Lee 2003; Lei and Taichun 2004;del Hoyo et al 2006). Currently the species status of the Taiwan population is not seriously in doubt and there has never been a real debate on its presumed close phylogenetic relationships to Regulus ignicapillus (Voous 1962;Desfayes 1965; Mayr and Short 1970;Eck 1996;Glutz von Blotzheim and Bauer 1991).…”

Hotspot analysis of Taiwanese breeding birds to determine gaps in the protected area network

“…Almost all of our species richness and hotspot analyses revealed that mountainous regions of Taiwan hold most of Taiwan's avian biodiversity. Previous studies showed a humpshaped relationship between avian species richness and Taiwan's elevation gradient, meaning that the highest species richness was found in mid-elevation forests (Koh and Lee 2003;Shiu and Lee 2003;Hsu et al 2004;Lee et al 2004;Ding et al 2005;Koh et al 2006b), which is unlike the species richness pattern found on Hainan Island, China in the northwestern South China Sea Columns 3 to 9 show how many of the grid cells of column 2 fell within the various protected area categories, followed by the percentages in brackets (e.g., for hotspot criterion 4, eight of a total of 47 grid cells (17.0%) were inside national parks). Note that the highest protection level (i.e., national parks) plus nature reserves, forest reserves, and wildlife refuges was defined as medium-to-high protection and that the addition of major wildlife habitats was then defined as low-to-high protection (see the 'Methods' section for details).…”