Wild Facts About The Blue Grosbeak
Quick Facts About Blue Grosbeaks
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Scientific Name |
Passerina caerulea (formerly Guiraca caerulea) |
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Common Name(s) |
Blue Grosbeak |
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Animal Type |
Songbird |
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Diet |
Insects and seeds. Especially fond of sorghum seed (Bull and Farrand Jr. 1994). May visit backyard bird feeders occasionally that offer black oil sunflower seeds, peanuts, and oranges. Feeds on the ground. |
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Found |
Throughout North Carolina but during the summer months only, usually arriving from the Bahamas, Cuba, and Central America by the end of April and leaving North Carolina around October. Look for Blue Grosbeaks in and around thickets, roadsides, and moist meadows. |
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Description |
Grows to 7.5 inches (19 cm), slightly smaller than the Northern Cardinal (Cardinalis cardinalis). Males: Deep blue overall, with a small, black face mask, black stripes on back, two chestnut wing bars (one thick, one thin), and black feathers at base of tail. Upper bill is black, lower bill is pale gray. Females: Dark tan to buff-brown with two chestnut wing bars. Gray bill. Both sexes: Short, thick, strong bill, black eyes, and black legs. |
Blue Grosbeak Images
Fun Facts About Blue Grosbeaks
Appearance Matters To Blue Grosbeaks
- Blue Grosbeaks pair up for mating but the bond is loose, and extra-pair mating is common in the species.
- In one study, 29 out of 55 Blue Grosbeak nestlings (52.7%) were sired by males other than the paired males and 14 of 20 (70%) of broods had at least one extra-pair offspring (Estep et al. 2005, https://doi.org/10.1139/z05-110).
- Male Blue Grosbeaks who have paired up with females simultaneously try to keep their females from mating with other males and try to mate with other, extra-pair females themselves.
- All mature male Blue Grosbeaks have blue feathers, but the brightness and saturation of the blue color vary across individual birds.
- The strongest and fittest males have the brightest blue plumage.
- Female Blue Grosbeaks notice the difference and prefer to mate with the brightest blue males.
- Male Blue Grosbeaks apparently compare their own brightness to the neighboring males and change their behavior if neighboring males are brighter.
- In the same study, the number of neighbors with deeper, brighter blue plumage predicted the intensity of mate-guarding behavior (Estep et al. 2005, https://doi.org/10.1139/z05-110).
Male Blue Grosbeaks Serenade The Countryside
- Blue Grosbeaks sing spontaneously.
- Out of 5,685 songs, 85% were uttered spontaneously rather than in response to the songs of nearby birds or after aggressive interactions (Lattin and Richardson 2009, https://doi.org/10.1676/09-026.1).
- Older Blue Grosbeaks had larger repertoires of song elements than younger birds
- An “element” was defined as “the smallest independent units produced by each male separated by periods of silence >50 msec, and typically made up of single notes”.
- Males sang the most before they paired off for mating and the least when incubating eggs.
