Goldfinches on the Hastings Natural History Reservation

Publication Type:Journal Article
Year of Publication:1957
Authors:Linsdale, JM
Journal:American Midland Naturalist
Volume:57
Issue:1
Date Published:1957
ISBN Number:00030031
Keywords:Carduelis, Carduelis carduelis, Corvidae, Fringillidae, Garrulus, Garrulus glandarius, Haemorhous, Haemorhous mexicanus
Abstract:The green-backed and the Lawrence goldfinches reveal close resemblances in their behavior. These bring them together in common flocks. Under some circumstances they also accept other related birds, for example, house finches. They seldom challenge larger birds. The green-backed goldfinch occupies greater area than the Lawrence goldfinch in California, and the population of the former species is greater. The Lawrence is found in hotter, drier parts of California than the green-backs. Southward from Los Angeles it is a bird of foothills or mountain valleys. Habitat conditions suited to these goldfinches are found on warm slopes, especially ones that face the southeast where warmth is available at nesting time. For perching and roosting they occupy trees with dense foliage. Trees in scrubby woodland with heavy festoons of lichens are suitable for nesting sites. Low bushes and tall herbaceous plants provide much of the food eaten by goldfinches. Creeks, or some other reliable source of water, where the birds can drink and bathe as well as obtain moisture to soften the dry, hard fruits that make up most of their food, are necessary. Additional requirements are for thickets that afford escape from hawks, jays and other predators. Pairing in these goldfinches occurs when the birds are in flocks. Courtship involves song and flight display. Males make high circular flights with wings and tails widely spread, revealing fully the courtship markings. The green-backed goldfinch has a long nesting season which extends from early March to July and, exceptionally, into November. The Lawrence occurs in variable numbers from year to year and it occupies a more restricted nesting area which tends to be concentrated southward. In winter this bird migrates toward the southeast. In the spring of some years the goldfinches congregate in large flocks with other seed-eating birds and forage on the seeds produced by the abundant plants that grow on open land that slopes toward the south. Nesting on the Reservation extends from May to July for the Lawrence goldfinch and for a longer period in the case of the green-backed goldfinch. The female does most of the nest building, but the male remains close by and sings. Some males carry small amounts of material and they are attracted to the nest site in its early stages. Frequently a member of a nesting pair will drive off a strange goldfinch. The female may pursue other females and sometimes strange males. The nesting pair tends to ignore the presence near the nest of the green-backed goldfinch. The incubating female in both species remains on the nest almost continuously. She may leave after some feedings by the male. The male brings food (moistened paste from seeds) about once each hour. After the young hatch the female broods the nestlings for about 4 days before she begins to accompany the male to get food. The green-backed and Lawrence goldfinches tend to forage together. The green-backs favor open pastures where Napa thistle grows. This plant is especially adapted to the needs of finches. Weed seeds provide the bulk of the food of these birds. The animal food reported from stomachs was mainly plant lice. On the Hastings Reservation we have watched green-backed goldfinches forage on 55 kinds of plant food, but the records show only 20 kinds of plant food eaten by the Lawrence. The contrast mainly is the result of differing abundance of the two species. The Lawrence goldfinch shows special preference for the seeds of fiddleneck, especially through the nesting season. In winter both species eat great amounts of chamise seeds. The nature of the food, and the manner of taking it, is conducive to taking large amounts of water. The habit of eating salt and sand is also related to alimentation in goldfinches. These sociable goldfinches exhibit varied relationships with other kinds of birds. Observed examples of association with other species of birds on the Reservation were recorded frequently. For the green-backed goldfinch 29 species and for the Lawrence goldfinch 19 species provided clear examples of association that represented awareness of near approach or some more important response that would influence the birds involved.
URL:http://www.jstor.org/stable/2422524
Short Title:American Midland Naturalist
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