Dickcissel

Spiza americana

Dickcissels breed in weedy overgrown fields with dense grassy and herbaceous vegetation. Nests are typically placed one meter above ground in briars, shrubs, small trees and clumps of grass (James and Neal 1986). As with many grassland species, Dickcissel numbers are declining. They have experienced an average annual decline of 3.5 percent between 1967 and 1989 according to the Breeding Bird Survey (Wilson 1990). Dickcissel numbers also fluctuate dramatically from year to year and from place to place (Robbins et al. 1986). Reasons for these fluctuations are uncertain. The overall decline may be partly due to habitat changes and pesticides. Additionally, they may be declining because of control procedures on their Venezuelan wintering ground (Basili and Temple 1995).

Code Frequency

Typically, males perch in open situations. Their wiry "dick..dick-cissel" song permits easy detection. Therefore, where they were not found during the Atlas Project, they likely occurred in low numbers or not at all. Higher breeding evidence was hard for Atlasers to find, however. Most probable breeding records were based on the abundance of singing males and observations of territoriality. Food being delivered to young accounted for most confirmed breeding records. Because the nests were difficult to observe, Dickcissels likely bred in most blocks in which they were recorded as possible and probable breeders. Unmated, "floating" males may have accounted for some of these records.

Distribution

Dickcissels occurred throughout all but the forested regions of Missouri. They were observed in only 30 percent of blocks in the Ozarks Natural Division compared with 70 percent in the remainder of Missouri. The greatest frequency of breeding confirmations occurred in the Osage Plains.

Average Number of Birds / 100 stops

Abundance

Correspondingly, Dickcissels were also most abundant in the Big Rivers and Mississippi Lowlands natural divisions.

Phenology

Dickcissels are late migrants to Missouri, arriving during the third week of April (Robbins and Easterla 1992). Atlasers observed nest building by May 7 and fledged young by May 25. Dickcissels typically raise two broods (Harrison 1975) and the late observation of a nest with young may represent a second brood. The observation of nest building July 29 was surprisingly late. Dickcissels typically begin to flock in late August in preparation for fall migration (Robbins and Easterla 1992).

Notes

Friedmann (1963) reported that parasitism of Dickcissels by Brown-headed Cowbirds was common. The Atlas Project recorded Brown-headed Cowbird parasitism in four of 18 blocks in which nest contents were observed.

Breeding Evidence

Reported in 977 (80.9%) of 1,207 blocks

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