Great Plains Natural Science Society


The Prairie Naturalist

Date of this Version


Document Type



The Prairie Naturalist 40(1/2): March/June 2008, pp 47-49


Provisioning of fruit to nestlings and possible sex-specific differences in feeding rate have not been reported for Bell's vireo (Vireo bellii; Brown 1993). While studying nesting ecology of Bell's vireo on Konza Prairie Biological Station, Geary and Riley counties, Kansas, I quantified feeding rate by sex and food type delivered to nestlings. Sex was determined by capturing adults with mist-nets and inspecting for a cloacal protuberance, as well as conducting behavioral observations of uniquely-marked individuals. Males sing regularly while moving around territories, as well as during incubation (Nolan 1960). I assigned "female" to the individual in these socially monogamous pairs that did not sing or appear to regularly patrol territorial boundaries. One-hour feeding samples were assigned randomly among five nests between 0600 and 1900 CST, preceded by a minimum IS-min interval. I used a 20- 60x Bushnell spotting scope in blinds 15 to 25 m from nests to sample provisioning to nestlings between 24 June and 15 August 1986. Nests contained three or four Bell's vireo nestlings within one day of age of each other. At all but one nest, males made the majority of feedings between days one and seven post-hatch (mean 62%, range 33-83%; n = 26 visits). No differences were apparent in adult feeding rate by sex from eight days post-hatch until t1edging at day 12 to 14, although a single nest received only female feedings the day of fledging (female mean 56%, range 42-100%; male mean 44%, range 0-58%; n = 36 visits). There were no detectable differences in prey size or type delivered by each sex.