American Robin (Turdus migratorius)

Vanderhoff, Natasha; Pyle, Peter; Patten, Michael A.; Sallabanks, Rex; James, Frances C.

doi:10.2173/bna.amrob.01

Cited by 6 publications

(2 citation statements)

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“…Treatments that reduce conifer saplings may reduce nesting opportunities for Hermit Thrush (Dellinger et al 2012), although foraging habitat effects may explain positive treatment relationships elsewhere (Gaines et al 2007). Positive treatment relationships for Cassin’s Finch and American Robin could reflect improved ground‐foraging opportunities with understory release in canopy openings (Hahn 1996, Gaines et al 2007, Kalies et al 2010, Vanderhoff et al 2016), although herbaceous growth did not correlate clearly with treatments. Numerous ground‐foraging species showing positive relationships with herbaceous cover here might respond positively to treatments that clearly stimulate herbaceous growth.…”

Section: Discussionmentioning

confidence: 99%

Dry conifer forest restoration benefits Colorado Front Range avian communities

Latif¹,

Truex

Sparks³

et al. 2020

Ecological Applications

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Fire suppression has increased stand density and risk of severe, stand‐replacing wildfire in lower elevation dry conifer forests of western North America, threatening ecological function. The U.S. Forest Service’s Collaborative Forest Landscape Restoration Program (CFLRP) aims to mitigate impacts to ecological function, while mandating effectiveness monitoring to verify restoration success. Expected benefits include improved conditions for biodiversity, but relatively few empirical studies evaluate restoration effects on biodiversity. We applied the Integrated Monitoring in Bird Conservation Regions program to survey birds in relation to CFLRP treatments along the Colorado Front Range in 2015–2017. We employed hierarchical models to analyze species occupancy and richness at 1972 points nested within 141 1‐km2 grid cells. Our objectives were to investigate (1) species occupancy relationships with treatments at local (point) and landscape (grid) spatial scales, (2) potential mechanisms for treatment relationships considering species and treatment relationships with forest structure and composition (i.e., habitat relationships), and (3) treatment and habitat relationships with species richness. The data supported positive and negative point‐level treatment relationships, suggesting uneven species distributions between treated and untreated points. At the grid scale, however, we only found positive species relationships with percent area treated, and accordingly, grid‐level species richness increased with treatment extent. Potential mechanisms for treatment relationships included treatments generating foraging opportunities for aerial insectivores by opening the canopy, improving conditions for ground‐associated species by increasing herbaceous growth, and limiting opportunities for shrub‐nesting species by reducing shrub cover. Landscape‐scale patterns suggest CFLRP treatments can benefit avian communities by generating habitat for open‐forest species without necessarily eliminating habitat for closed‐forest species. Our results provide evidence for a commonly expected but rarely verified pattern of increased species richness with forest heterogeneity. We suggest restoration treatments will most benefit forest bird diversity by reducing canopy cover, encouraging herbaceous ground cover, limiting ladder fuel species, and encouraging shrub diversity in canopy openings, while maintaining some dense forest stands on the landscape.

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Section: Discussionmentioning

confidence: 99%

Dry conifer forest restoration benefits Colorado Front Range avian communities

Latif¹,

Truex

Sparks³

et al. 2020

Ecological Applications

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“…For the trials in which two cameras were on either side of the nest, the numbers of left and right head tilts observed from both videos were averaged to minimize bias from the camera angle. In robins, only females incubate the eggs [38] and so our observed head tilts counted should represent maternal behaviours. To assess the replicability of our methods, all the videos were viewed and scored separately by two people (H.M.S.…”

Section: Materials and Methods (A) Experimentsmentioning

confidence: 99%

Mimicry-dependent lateralization in the visual inspection of foreign eggs by American robins

et al. 2019

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Brain lateralization, or the specialization of function in the left versus right brain hemispheres, has been found in a variety of lineages in contexts ranging from foraging to social and sexual behaviours, including the recognition of conspecific social partners. Here we studied whether the recognition and rejection of avian brood parasitic eggs, another context for species recognition, may also involve lateralized visual processing. We focused on American robins ( Turdus migratorius ), an egg-rejecter host to occasional brood parasitism by brown-headed cowbirds ( Molothrus ater ) and tested if robins preferentially used one visual hemifield over the other to inspect mimetic versus non-mimetic model eggs. At the population level, robins showed a significantly lateralized absolute eyedness index (EI) when viewing mimetic model eggs, but individuals varied in left versus right visual hemifield preference. By contrast, absolute EI was significantly lower when viewing non-mimetic eggs. We also found that robins with more lateralized eye usage rejected model eggs at higher rates. We suggest that the inspection and recognition of foreign eggs represent a specialized and lateralized context of species recognition in this and perhaps in other egg-rejecter hosts of brood parasites.

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Bluebirds Experience Impaired Hatching Success in Conventionally Sprayed Apple Orchard Habitats: A 31‐Year Study

Read¹,

English

Hick

et al. 2021

Enviro Toxic and Chemistry

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We analyzed the reproductive success of eastern bluebirds (Sialia sialis) nesting in apple orchards and non-orchard nest-boxes in southern Ontario, Canada, from 1988 to 2018. Using data from 2397 nest-boxes monitored at 20 orchard sites and 52 non-orchard sites, we first modeled phenological parameters typically linked to climate change across both site types. We found that the first egg of each brood was laid significantly earlier in the season each year over our 31-year study. Clutch initiation occurred 4 days earlier in the spring in 2018 compared to 1988. Average clutch size in the first or second brood did not change significantly during our 31-year study; however, clutches were significantly smaller in orchards compared to nonorchards (0.10 ± 0.03 fewer eggs between sites). Nests built in orchards were also at 6.1-fold greater risk of parasitism and 2.1-fold greater risk of depredation than nests in non-orchards. After accounting for depredation and nest parasitism, hatching success was still significantly lower in orchards than in non-orchards. Overall, hatching success was 4%-5% lower in orchards. The probability of successfully fledging did not differ significantly between site types. In 2012, a ban on use of the organophosphate insecticide azinphos-methyl in orchards was enacted in Canada. We did not find a difference in hatching or fledging success in orchards after the ban. In our assessment of available data, we conclude that any pesticide effect on hatching success of eastern bluebirds in sprayed orchards is most likely the consequence of long-term exposure to dichlorodiphenyltrichloroethane (DDT) compounds in orchard soils and bioaccumulation in eggs rather than pesticides in use since regulation of DDT in the 1970s.

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American Robin (Turdus migratorius)

Cited by 6 publications

References 0 publications

Dry conifer forest restoration benefits Colorado Front Range avian communities

Dry conifer forest restoration benefits Colorado Front Range avian communities

Mimicry-dependent lateralization in the visual inspection of foreign eggs by American robins

Bluebirds Experience Impaired Hatching Success in Conventionally Sprayed Apple Orchard Habitats: A 31‐Year Study

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