Eastern Bluebirds Eject Brown-Headed Cowbird Eggs

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.

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First Evidence of Conspecific Brood Parasitism and Egg Ejection in Song Sparrows, With Comments on Methods Sufficient to Document These

The Condor ◽

10.1093/condor/108.2.452 ◽

2006 ◽

Vol 108 (2) ◽

pp. 452-458

Author(s):

Quresh S. Latif ◽

J. Letitia Grenier ◽

Sacha K. Heath ◽

Grant Ballard ◽

Mark E. Hauber

Keyword(s):

Genetic Analysis ◽

Brood Parasitism ◽

Nest Predation ◽

Molothrus Ater ◽

Separate Study ◽

Conspecific Brood Parasitism ◽

Egg Ejection ◽

Song Sparrows ◽

Cowbird Parasitism ◽

Egg Marking

Abstract Conspecific brood parasitism occurs in many songbird species but has not been reported in Song Sparrows (Melospiza melodia). In three separate study areas where breeding Song Sparrows experience heavy nest predation pressure and Brown-headed Cowbird (Molothrus ater) parasitism, we observed six instances in which newly laid eggs were attributable to female Song Sparrows other than the nest owners. We also recorded the ejection of a sparrow egg from each of two videotaped nests. In a fourth study area without cowbird parasitism, genetic analysis of parentage revealed no conspecific brood parasitism. Given that egg ejection can accompany conspecific parasitism in Song Sparrows, we suggest that daily nest checks are insufficient to document the frequency of this tactic in some species in the absence of egg marking, videotaping, or genetic analyses. Since standard nest monitoring techniques may fail to detect conspecific brood parasitism, this behavior could be more prevalent than currently thought.

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Ectoparasitic blow flies (Protocalliphora sp.) and nestling Eastern Bluebirds (Sialia sialis): direct effects and compensatory strategies

Canadian Journal of Zoology ◽

10.1139/z06-079 ◽

2006 ◽

Vol 84 (7) ◽

pp. 921-930 ◽

Cited By ~ 25

Author(s):

Kristina Hannam

Keyword(s):

Brood Reduction ◽

Direct Effects ◽

Negative Effects ◽

Compensatory Strategies ◽

Blow Flies ◽

Sialia Sialis ◽

Eastern Bluebird ◽

Eastern Bluebirds ◽

Nestling Period ◽

Host Parasite

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.

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Annual Productivity and Its Measurement in a Multi-Brooded Passerine, the Eastern Bluebird

The Auk ◽

10.1093/auk/96.3.562 ◽

1979 ◽

Vol 96 (3) ◽

pp. 562-572

Author(s):

Benedict C. Pinkowski

Keyword(s):

Success Rate ◽

Age Groups ◽

Nesting Success ◽

Egg Laying ◽

Success Rates ◽

Sialia Sialis ◽

Eastern Bluebird ◽

Annual Productivity ◽

Eastern Bluebirds ◽

Breeding Seasons

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.

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Observations of Fecal Sac Disposal by Eastern Bluebirds

The Condor ◽

10.1093/condor/104.1.205 ◽

2002 ◽

Vol 104 (1) ◽

pp. 205-207 ◽

Cited By ~ 1

Author(s):

Jason D. Lang ◽

Carrie A. Straight ◽

Patricia Adair Gowaty

Keyword(s):

Parental Behavior ◽

Average Distance ◽

Sialia Sialis ◽

Eastern Bluebird ◽

Eastern Bluebirds ◽

Utility Poles

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.

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Differential Effects of Elevated Nest Temperature and Parasitism on the Gut Microbiota of Wild Avian Hosts

10.21203/rs.3.rs-600854/v1 ◽

2021 ◽

Author(s):

Melissa R Ingala ◽

Lauren Albert ◽

Alyssa Addesso ◽

Mackenzie J. Watkins ◽

Sarah A. Knutie

Keyword(s):

Gut Microbiota ◽

Bacterial Communities ◽

Tree Swallow ◽

Sialia Sialis ◽

Eastern Bluebird ◽

Eastern Bluebirds ◽

Host Health ◽

Natural Nest ◽

The Face ◽

Host Parasite

Abstract Background: Changes in wild animal gut microbiotas may influence host health and fitness. While many studies have shown correlations between gut microbiota structure and external factors, few studies demonstrate causal links between environmental variables and microbiota shifts. Here, we use a fully factorial experiment to test the effects of elevated ambient temperature and natural nest parasitism by nest flies (Protocalliphora sialia) on the microbiotas of two species of wild birds, the eastern bluebird (Sialia sialis) and the tree swallow (Tachycineta bicolor).Results: We find that bacterial communities from the nestlings of each host species show differential response to both heat and parasitism, with gut microbiotas of eastern bluebirds more disrupted by heat and parasitism than those of tree swallows. Thus, we find that eastern bluebirds are unable to maintain stable associations with their gut bacteria in the face of both elevated temperature and parasitism. In contrast, tree swallow gut microbiotas are not significantly impacted by either heat or nest parasitism.Conclusions: Our results suggest that excess heat (e.g., as a result of climate change) may destabilize natural host-parasite-microbiota systems, with the potential to affect host fitness and survival in the anthropocene.

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Reproductive success of Eastern Bluebirds (Sialia sialis) varies with the timing and severity of drought

10.1101/575647 ◽

2019 ◽

Author(s):

Reneé E. Carleton ◽

John H. Graham ◽

Adel Lee ◽

Zachary P. Taylor ◽

Jon F. Carleton

Keyword(s):

Reproductive Success ◽

Spatial Scales ◽

Vegetation Indices ◽

Drought Severity ◽

Climate Data ◽

Sialia Sialis ◽

Eastern Bluebird ◽

Governmental Agencies ◽

Eastern Bluebirds ◽

Clutch Initiation

AbstractDrought affects avian communities in complex ways. We used our own and citizen science-generated reproductive data acquired through The Cornell Lab of Ornithology’s NestWatch Program, combined with drought and vegetation indices obtained from governmental agencies, to determine drought effects on Eastern Bluebird (Sialia sialisL.) reproduction across their North American breeding range for the years 2006–2013. Our results demonstrate that some aspects of bluebird reproductive success varies with the timing and severity of drought. Clutch size was unaffected by drought occurrence or severity during or within one and two months of clutch initiation, but hatching and fledging rates decreased as drought severity increased. Drought conditions occurring one month prior to the month during which eggs should have hatched, and two months prior to the month nestlings should have fledged also reduced the numbers of fledged offspring. We also demonstrate the value of datasets generated by citizen scientists in combination with climate data for examining biotic responses at large temporal and spatial scales.

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Differential effects of elevated nest temperature and parasitism on the gut microbiota of wild avian hosts

Animal Microbiome ◽

10.1186/s42523-021-00130-3 ◽

2021 ◽

Vol 3 (1) ◽

Author(s):

Melissa R. Ingala ◽

Lauren Albert ◽

Alyssa Addesso ◽

Mackenzie J. Watkins ◽

Sarah A. Knutie

Keyword(s):

Gut Microbiota ◽

Tree Swallow ◽

Nest Parasitism ◽

Sialia Sialis ◽

Eastern Bluebird ◽

Eastern Bluebirds ◽

Host Health ◽

Natural Nest ◽

The Face ◽

Host Parasite

Abstract Background Changes in wild animal gut microbiotas may influence host health and fitness. While many studies have shown correlations between gut microbiota structure and external factors, few studies demonstrate causal links between environmental variables and microbiota shifts. Here, we use a fully factorial experiment to test the effects of elevated ambient temperature and natural nest parasitism by nest flies (Protocalliphora sialia) on the gut microbiotas of two species of wild birds, the eastern bluebird (Sialia sialis) and the tree swallow (Tachycineta bicolor). Results We find that bacterial communities from the nestlings of each host species show idiosyncratic responses to both heat and parasitism, with gut microbiotas of eastern bluebirds more disrupted by heat and parasitism than those of tree swallows. Thus, we find that eastern bluebirds are unable to maintain stable associations with their gut bacteria in the face of both elevated temperature and parasitism. In contrast, tree swallow gut microbiotas are not significantly impacted by either heat or nest parasitism. Conclusions Our results suggest that excess heat (e.g., as a result of climate change) may destabilize natural host-parasite-microbiota systems, with the potential to affect host fitness and survival in the Anthropocene.

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