Conserving birdlife of Peruvian highland bogs: effects of patch-size and habitat quality on species richness and bird numbers
Published: Volume 53(2), December 2006. Pages 271-283.
Aims: Bogs (locally named "bofedales") constitute a key habitat for conserving birds associated with the wet meadows and ponds on the huge expanses of dry bunch-grass steppes ("puna") of the Andes. Despite this, the factors shaping bird numbers and species richness in this habitat have not been studied. This paper examines the bird communities in a set of bogs distributed in two Peruvian localities during the wet (February) and dry (September) season. It evaluates the effects of bog size and some habitat features (grazing intensity, presence of small watercourses, vegetation cover, etc.) on abundance and species richness of bird communities.
Location: Two Peruvian localities above 4,000 m (humid mountains near Cusco, and arid uplands near Arequipa).
Methods: Given that bogs tended to be long and narrow (mean width: 59 m, range 10 - 200 m), birds were counted along three parallel, simultaneous transects covering the full area of bogs. Independent variables evaluated were the size (ha), altitude (m above sea level), slope (0-90º), presence/absence of small permanent watercourses and cover (%) of water, meadows and cushion-like Yareta shrubs in each study bog. Grazing intensity was estimated by counting the number of faecal pellet groups (of alpacas and other livestock) inside a one-metre-wide band transect.
Results: Results support the view that bogs operate as local "hotspots" for birds, as they maintain species associated with different habitats, such as rivers and lakes (Anas flavirostris, Anas specularoides, etc.), wet meadows (Vanellus resplendens, Chloephaga melanoptera, Cinclodes fuscus, Lessonia oreas, etc.) or bunch-grass steppes (Metriopelia aymara, Thinocorus orbignyianus, etc.). Bird species richness and numbers were positively correlated with bog size and, after controlling for this effect, species richness increased in those arid upland bogs crossed by small watercourses during the dry period. This supports the key role of water availability on the bird communities of these steppes. No effect of grazing intensity and other habitat features were recorded.
Conclusions: From a conservation perspective, bog size and the presence of permanent watercourses seem to be two focal criteria for prioritizing relevant bogs for protection and can also be used as key guidelines for evaluating the pervasive effects of the reduction and alteration of bogs by public works (roads), agricultural encroachment or draining.