Kimberly G. Smith

Acorn preference of urban blue jays (Cyanocitta cristata) during fall and spring in northwestern Arkansas

We censused 26 acorn-bearing trees of six oak species for Blue Jays (Cyanocitta cristata) during fall of 1985 on the University of Arkansas campus. The following spring we presented six piles, each containing 20 acorns from a different oak species, to free-ranging jays to determine acorn preference in spring. Trees censused and acorns presented were from both black oak (BO) and white oak (WO) subgenera, which differ in size, percent fat, tannin content, and germination time. In fall, Blue Jays were observed removing acorns from three species of oaks with small acorns, particularly those of willow oaks (BO, Quercus phellos), and were rarely observed in trees of three other oaks with large acorns. When offered a choice of acorns from six oak species in spring, Blue Jays showed a preference, based on Ivlevs electivity index, for small acorns, particularly those of pin oaks (BO, Q. palustris), and an avoidance of large acorns. Thus, small size appears to be an important trait associated with acorn preference in Blue Jays. Acorns of the introduced English oak (WO, Q. robur), which are preferred by Euorpean Jays (Garrulus glandarius) (Bossema 1979), also were avoided in spring by Blue Jays, suggesting that familiarity may be a general component of acorn selection by jays.

Habitat Occupancy by Rusty Blackbirds Wintering in the Lower Mississippi Alluvial Valley

Abstract. The Rusty Blackbird (Euphagus carolinus) has declined by 90% since the 1960s, possibly from conversions of forested wetlands in the southeastern U.S. to agriculture. Because its habitat use during the nonbreeding season had not been quantified, we estimated occupancy rates of Rusty Blackbirds wintering in the lower Mississippi Alluvial Valley in relation to habitat type (four types of bottomland forest and adjacent agricultural fields), tree density, canopy cover, and water cover. In January and February, we surveyed 89 sites eight times during 2006, 117 and 109 sites 10 times during 2007 and 2008, respectively. Occupancy of individual birds, estimated from their presence or absence at a site, was generally high and greater in 2006 (0.71) than during either 2007 (0.43) or 2008 (0.37). Occupancy of flocks, estimated from presence or absence of ≥20 individuals, was highest in 2006 (0.46), lowest in 2007 (0.17), and intermediate in 2008 (0.30), possibly because of water levels fluctuating from year to year. Rusty Blackbirds were not as specialized in habitat use as expected; habitat characteristics did not consistently predict occupancy of either individuals or flocks. Occupancy of individuals increased with canopy cover during 2007, and occupancy of flocks decreased with tree density during 2006. In 2008, occupancy of individuals increased with tree density and was higher in wet bottomland forest (0.51) than in other habitats (0.31–0.35). Further research is needed to determine whether this lack of habitat specificity is widespread and possibly the result of diverse food requirements during the nonbreeding season.

Pair interactions in red-faced warblers

Forty pairs of breeding Red-faced Warblers (Cardellina rubrifrons) were observed in 1992 and 1993 on the Mogollon Rim, Arizona. Intrusions by extra-pair males, interactions between pair members, and other pair interaction behaviors were recorded. The majority of intrusions occurred during the building stage of the nesting cycle. Males responded to intrusions during nest building by decreasing intra-pair distance. Males maintained shorter intra-pair distances by following the female when she initiated movements and by not initiating pair movements themselves. Intra-pair distances were as short or shorter during the incubation period as during nest building, and were shorter during incubation than during egg laying. Males continued to follow females beyond the expected fertile period. Possible explanations for continued mate following include: males guard their mates against predators, males guard their paternity for future nesting attempts, and males respond to extra-pair male intrusions, which continue during incubation.

Additional evidence of multiple parentage in eastern bluebirds

Cavity-nesting Eastern Bluebirds (Sialia sialis) were thought to be monogamous (Pinkowski 1974, Gowaty 1980), but Verner and Willson (1969), Gowaty and Karlin (1984), and later Gowaty (1985) and Gowaty and Bridges (unpubl.) found genetic evidence to the contrary. Because selective pressures on behavioral traits may differ greatly between populations, it is necessary to know whether geographically distant populations exhibit similar behavioral characteristics. Here we report on a sample of Eastern Bluebirds from a different population and provide evidence ofnondescendent offspring of at least one putative parent.