Regulation of food supply by feeding territoriality in the rufous hummingbird

Abstract

This field study of female and immature migratory rufous hummingbirds (Selasphorus rufus) reveals that their feeding territories are closely regulated in size to maintain environmental reserves of energy per individual. Columbine (Aquilegia formosa) produces nectar about four times as fast per nectary as Indian paintbrush (Castilleja miniata) but territories have similar daily caloric productivity regardless of their floral species composition.Une étude en nature de femelles et d'oisilons du colibri migrateur Selasphorus rufus démontre que les territoires où ils se nourrissent sont délimités de façon à ce qu'il y ait dans le milieu une réserve constante d'énergie par individu. L'ancolie (Aquilegia formosa) produit son nectar environ quatre fois plus vite par nectaire que la castilléjie Castilleja miniata, mais les territoires ont des productivités caloriques quotidiennes semblables, quelle que soit la composition de la population florale.[Traduit par le journal]

Status and foraging in New Zealand honeyeaters

“…These failings are more easily overcome with nectar-feeding birds. For example, interactions between species are commonly observed at nectar sources, which suggests interference competition, and a number of studies have shown that nectar is limiting (e.g., in a hummingbird community [Gass et al 1976]; in a honeyeater community [Ford & Paton 1976;Ford 1979]). The ease which nectar-feeding birds will use artificial sugar sources has even allowed testing of some of these ideas (S. Pimm, pers.…”

Spatial memory in rufous hummingbirds (Selasphorus rufus): A field test

“…Individuals of many species of hummingbird defend a territory, the size of which is determined by food supply in terms of the number of flowers within the territory or the amount ofnectar produced by them (Gass, Angehr, & Centa, 1976;Kodric-Brown & Brown, 1978). In the course of a day, a hummingbird will visit hundreds of nectar sources and thus seriously affect the abundance and distribution of food for subsequent foraging bouts.…”

“…These feeding territories consist of over 200 flowers (Armstrong et al, 1987;Paton & Carpenter, 1984), and the owners vigorously defend them from conspecifics attempting to rob nectar. Because flowers may take some considerable time to replenish (Gass et al, 1976), a hummingbird may follow one or several strategies in order not to revisit recently emptied flowers: visiting flowers in a consistent pattern whereby Copyright 1995 Psychonomic Society, Inc. memory is required only for the pattern and not the flowers themselves ("trap-lining";Feinsinger, 1978), visiting clumps of flowers and remembering the clump visited but not the individual flowers themselves, and remembering the specific locations of individual flowers. Each of these possible strategies has been discussed previously, and there is support from optimality models and experimental tests for the first two (Davies & Houston, 1981;Gill & Wolf, 1977;Kamil, 1978).…”

Energy limitation of hummingbird populations in tropical and temperate communities

“…Total hummingbird biomass = 2; (N~ x W~), where, for species i, W~ is its average body weight (from Gass et al 1976, Montgomerie 1979, and N~ is the number recorded on the census.…”