Breeding biology of the black-backed lesser goldfinch in ponderosa pine forests on the colorado front range
2002
We present information on nest site characteristics and breeding biology of the black-backed race of the Lesser Goldfinch (Carduelis psaltria psaltria) in montane ponderosa pine (Pinus ponderosa) woodland in the foothills of Boulder County, Colorado. We located 62 nests during summer, 1999––2001. There appeared to be strong microhabitat preferences for nest sites. Nests generally were placed toward tips of long branches in the middle of ponderosa pines. Most nests were well concealed in needle clusters in trees near forest edges and openings. Mean canopy cover at nest sites was 49%%. Nests usually were oriented toward the south or east, and orientation was correlated with the aspect of the surrounding terrain. More than 70%% of nests were located in small, loose colonies. Nesting success was fairly high; at least 21 nests fledged young while only 10 failed due to predation. Mayfield nest success was 73%% during 2000 and 52%% during 2001. Most predation events occurred after the eggs had hatched. We found only one instance of brood parasitism by the Brown-headed Cowbird (Molothrus ater). Compared to the green-backed race (C. p. hesperophila), Black-backed Lesser Goldfinches appear to breed later in the season and have smaller clutch sizes.
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