Eastern Bluebird (Sialia sialis)

Author(s):  
Patricia A. Gowaty ◽  
Jonathan H. Plissner

2006 ◽  
Vol 84 (7) ◽  
pp. 921-930 ◽  
Author(s):  
Kristina Hannam

Variation in environmental factors such as parasitism can have direct effects on an organism’s fitness. Because parasites draw resources directly from their hosts, they are expected to have negative effects; however, several nestling host – parasite systems show no evidence of direct effects. Absence of direct effects may be explained by compensation strategies used by parents or nestlings themselves. In this study evidence for both direct effects and compensatory strategies in a blow fly (genus Protocalliphora Hough, 1899) – Eastern Bluebird (Sialia sialis (L., 1758)) system were examined. Nestlings showed no direct effects of blow flies on survival and on size at fledging; however, parasitized broods were significantly anemic. There was no evidence for compensation by parents in the form of brood reduction and there was no support for compensation by nestlings via a hierarchy of tissue preservation. Nestlings did compensate for parasitism by accelerating growth at the end of the nestling period and delaying fledging.



2021 ◽  
Vol 20 (4) ◽  
Author(s):  
Melinda J. Schuman ◽  
Susan L. Snyder ◽  
Copley H. Smoak ◽  
Carla J. Dove


The Auk ◽  
1979 ◽  
Vol 96 (3) ◽  
pp. 562-572
Author(s):  
Benedict C. Pinkowski

Abstract Breeding and demographic parameters are examined for 434 Eastern Bluebirds (Sialia sialis) attempting 324 nests in southeastern Michigan during 1968-1977. Nesting birds spent an average of 10.4 weeks (63.9% of a 16.2-week season) in the study area. Only 154 (35.5%) of the nesting birds remained for entire breeding seasons; these season-long residents averaged 2.14 nests/season and had a higher success rate (68.4%) and presumably greater productivity (5.6 young · pair−1 · season −1) than other birds because site fidelity depends on nesting success. Although two seasonal peaks for egg-laying were observed, only 75 of 357 birds (21.0%) successfully raised two broods. Evidence is presented to suggest that birds observed for only part of a season initiated nests at the same rate while in and not in the study area, so that an average annual productivity value of 5.0 young · pair−1 · season −1 is calculated for all nesting birds from the observed success rate (57.1%) and mean length of stay in the area. Estimated average productivity of yearlings (4.3 young · pair−1 · season −1) was lower than that of adults (5.7 young · pair−1 · season −1) although nesting success rates were similar in the two age groups.



The Condor ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 741-745 ◽  
Author(s):  
Brian D. Peer ◽  
Lyndon R. Hawkins ◽  
Edwin P. Steinke ◽  
Patricia Blair Bollinger ◽  
Eric K. Bollinger

Abstract The relationship between the Brown-headed Cowbird (Molothrus ater) and its cavity-nesting hosts has received little attention because of the assumption that cowbirds rarely parasitize these hosts. We tested the Eastern Bluebird (Sialia sialis), a host that is sometimes heavily parasitized by cowbirds, for egg ejection behavior. Bluebirds ejected 65% of experimentally added cowbird eggs (n  =  20), but ejected no experimentally added conspecific eggs (n  =  66). This suggests that cowbird parasitism, not conspecific brood parasitism, is the selective pressure responsible for egg ejection in this species. This level of rejection may be conservative because bluebirds nest in dark cavities, which may make cowbird eggs difficult to detect by bluebirds.



The Condor ◽  
2002 ◽  
Vol 104 (1) ◽  
pp. 205-207 ◽  
Author(s):  
Jason D. Lang ◽  
Carrie A. Straight ◽  
Patricia Adair Gowaty

Abstract During systematic observations of Eastern Bluebird (Sialia sialis) parental behavior near Athens, Georgia, we observed adults placing fecal sacs on electric wires. Adults also placed fecal sacs on fence posts, tree branches, and utility poles. Females and males did not dispose of fecal sacs differently or remove fecal sacs at different rates. Adults carried fecal sacs 91 ± 11 m before disposal, 21–52 m (95% CI) farther than their average distance from the nest. This finding is consistent with the hypothesis that fecal sac removal reduces cues predators use to locate nests. Observaciones sobre la Disposición de Sacos Fecales en Sialia sialis Resumen. Durante observaciones sistemáticas del comportamiento parental de Sialia sialis en las cercanías de Athens, Georgia, observamos la colocación de sacos fecales en cables eléctricos. Los adultos también dejaron sacos fecales en postes de cercas, ramas de árboles y postes de alumbrado. No se encontraron diferencias entre machos y hembras en la tasa de colocación de sacos fecales ni en la manera como dispusieron de los mismos. Los adultos viajaron con los sacos fecales en promedio 91 ± 11 m antes de abandonarlos, unos 21–52 m (intervalo de confianza del 95%) más lejos que la distancia promedio desde el nido. Estos resultados son consistentes con la hipótesis que la remoción de los sacos fecales reduce señales que los predadores podrían usar para localizar los nidos.





2013 ◽  
Vol 58 (3) ◽  
pp. 386-388
Author(s):  
Jennifer L. Burtka ◽  
Jennifer L. Grindstaff


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