Dead-leaf foraging specialization in tropical forest birds: Measuring resource availability and use
Studies in Avian Biology
1990
Journal Article
13
360-368
Reserva Nacional Tambopata animals birds animal behavior foraging habitat selection leaves habitat heterogeneity predation ecology Madre de Dios Bibliography
Tropical birds foraging at dead leaves suspended above the ground in forest understory represent a system that potentially overcomes many of the difficulties inherent in measuring resource availability for insectivorous birds. Because the dead leaves are discrete and abundant resource patches, they are easily counted and sampled. A scheme for sampling the availability and use of specific substrate types and the abundances of arthropod prey is presented. Availability and use are compared directly for six bird species in three habitats (upland rainforest, low-lying rainforest, and bamboo) at the TRZ. It has been concluded that (1) the overall abundance, variety, and high prey productivity of dead leaves helps to maintain extreme specialization in this guild; (2) substrate types are selected nonrandomly by all species, at least partly on the basis of the differential prey availability in each type; (3) individual dead leaves are relatively long-lived and are continually recolonized by arthropods, therefore representing predictable and renewable resource patches to these birds; (4) dead-leaf specialists are exposed to distinctly different prey choices from those of birds that search live foliage. Studies of other insectivorous bird groups should include estimates of substrate availability among habitats, prey availability among substrates, as well as the use of these by the birds.