Human impact on bird diversity and community structure in a tropical montane cloud forest in Alta Verapaz, Guatemala, with special reference to the Quetzal (Pharomachrus mocinno)

Abstract

Using birds as an exemplary animal group, the human influence on diversity, community structure and nutrition guild composition is examined in tropical montane cloud forest in Guatemala. Human impact is measured as differences in diversity and body mass in both natural forest and secondary forest (as a consequence of slash-and-burn agriculture). A comparison of these measures is made between the two different habitat types. In terms of species richness, α-diversity (punctual diversity) is higher in used habitats than in natural forest. However, the mean body mass per species is lower in secondary growth than in natural forest. The latter implies that the nutritional conditions of birds in natural forest are qualitatively better than in secondary vegetation. The remaining natural forests in the study area in the region of Alta Verapaz are highly fragmented and have been reduced to less than 50 % of its original cover. Some species are considered to be extinct (e.g. Oreophasis derbianus Mountain Guan) or are threatened to vanish from the study area like, e.g., Penelopina nigra Highland Guan, Pharomachrus mocinno Resplendent Quetzal. Both of these species are dependent on natural forest, the latter because of breeding holes. Both species will become extinct when the last natural forest is gone, which with the current mean national deforestation rate in Guatemala, is within 120 years. The study area is located in the mountain cloud forest zone of the Sierra Yalijux, Alta Verapaz, Guatemala (15°28′N,90°20′W) between 1,900 and 2,550 m. The investigations were conducted within a 102 ha study plot, including both habitat types with equal spatial dimensions. Birds were censused with several standardised methods. The main factor for fragmentation and deforestation — i.e., habitat loss — is slash-and-burn agriculture by peasants. The Resplendent Quetzal Pharomachrus mocinno was used as an example to explain the limiting factors of the regional populations and estimate their viability.