Dickcissel Life History

Habitat

Habitat Grasslands

Throughout the year Dickcissels require grassland habitats, but they are rarely picky about those habitats. In the summer months they are most common in native prairies and restored grasslands, but they also nest in lightly grazed pastures, hayfields, fallow agricultural fields, and even fencerows and roadsides. In their wintering range they live in similar open places, and large flocks of wintering Dickcissels can be found on grasslands and croplands. They require access to three distinct habitats in the winter: natural grasslands or crop fields for foraging, resting areas with brushy vegetation, and nocturnal roost sites in densely vegetated marshes or tall native grasslands.

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Food

Food Seeds

During the breeding season, Dickcissels eat both insects and seeds. Insects include grasshoppers, caterpillars, termites, flies, wasps, beetles; they also eat spiders. On migration and in winter, they eat almost exclusively seeds including grasses, willows, and buckwheat as well as crops including rice and sorghum. They can hull and eat upwards of a dozen sorghum seeds per minute, with males slightly faster at shelling seeds than females.

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Nesting

Nest Placement

Nest Shrub

Dickcissels put their nests near the ground in dense grasses and sedges. In places where there are woody plants, they will occasionally place them 10 or more feet above the ground.

Nest Description

Female Dickcissels build the nest, a bulky cup woven out of weeds and grasses. The interior is often lined with fine grass and, sometimes, hair.

Nesting Facts
Clutch Size:3-6 eggs
Number of Broods:1-2 broods
Egg Length:0.8-0.9 in (2-2.2 cm)
Egg Width:0.6-0.7 in (1.6-1.7 cm)
Incubation Period:12-13 days
Nestling Period:8-10 days
Egg Description:

Unmarked, pale blue.

Condition at Hatching:

Nearly naked with sparse white down, helpless.

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Behavior

Behavior Ground Forager

Male Dickcissels are aggressive defenders of their primary territory, keeping a close eye on their immediate neighbors by confronting each other at territorial boundaries. They do this by dropping to the ground and approaching each other sidelong. When intruders overstep their bounds, they are chased with twisting, turning flights that often end with the birds fighting on the ground. Dickcissels are often polygynous, meaning that some males mate with more than one female. Males with better territories, featuring dense and deep vegetation, attract more females than those without. Most males have only one mate, but some have two or three. When a female settles in his territory, a male Dickcissel is an attentive mate, accompanying her as she forages or inspects nest sites. A male will not take a second mate until the first has begun nesting. The male does not participate in any aspect of parental care but spends the entire season defending his territory. While Dickcissels are mostly solitary and territorial in the breeding season, the rest of the year they are extremely gregarious. Wintering birds gather in massive flocks, occasionally numbering into the millions. Each flock roosts independently, and while individual DIckcissels sometimes shift between different roosts, most seem to remain at one throughout the winter.

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Conservation

Conservation Low Concern

Dickcissel populations declined during the late 1960s and 1970s but then stabilized. Partners in Flight estimates an overall 14% decline since 1970, with a global breeding population of 28 million. The species rates an 11 out of 20 on the Continental Concern Score, indicating it is a species of low conservation concern. On their breeding grounds, Dickcissels are under threat from alteration of habitat, specifically large-scale conversion of native grasslands to row crops. Increased availability of hayfields and fallow fields have the potential to provide breeding habitat, but hayfields are often mowed before nesting Dickcissels have time to fledge their young. The greatest threat to Dickcissels is on their wintering grounds in the llanos region of Venezuela, where flocks can number in the millions. There, the birds may be regarded as pests to ripening grain crops; since the 1960s, roosting birds have been sprayed at night with pesticides, causing massive mortality. As agricultural production of rice and sorghum in Venezuela has expanded, and Dickcissel populations have decreased, the proportion of crops eaten by Dickcissels has declined significantly. Nonetheless, Dickcissels continue to be illegally targeted.

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Credits

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr. Ziolkowski, D. J. and W. A. Link. The North American Breeding Bird Survey, results and analysis 1966-2013 (Version 1.30.15). USGS Patuxtent Wildlife Research Center (2014b). Available from http://www.mbr-pwrc.usgs.gov/bbs/.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

Temple, Stanley A. (2002). Dickcissel (Spiza americana), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

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