Long-Distance Dispersal By Eastern Gray Squirrels In Suburban Habitats

Natal dispersal by Sciurus carolinensis (Eastern Gray Squirrel) is poorly understood, given so rarely reported, yet dispersal patterns in small mammals can affect seed dispersal and predation, as well as population dynamics of predators. Herein, I document long-distance dispersal by 3 Eastern Gray Squirrels from the suburban coastal campus of the University of New England in Biddeford, ME. Mean dispersal distance was 10.1 km (min–max = 6.3–14.5 km), occurring in random directions (SW, S, NW). These results, combined with the previous studies, better describe the distribution of natal dispersal by Eastern Gray Squirrel—critical information in understanding population processes and potentially developing effective landscape-management strategies

Prevalent Transoceanic Fall Migration By A 30-Gram Songbird, The Bobolink

Three North American passerines are known to perform transoceanic flights during their fall migration, with open-water flights ranging in length from 1,700 to 3,400 km. However, little is known about within-population variation of these flights. From 2013 to 2017, I used geolocators to study variation in the fall migratory track of the Bobolink (Dolichonyx oryzivorus) from a population that bred in agricultural grasslands of Vermont, USA. Thirteen of seventeen birds took transoceanic flights during fall migration, ranging in length from 1,098 to 3,536 km (mean ± SD = 1,969 ± 640); five of these flights were nonstop from North to South America. Bobolinks initiated transoceanic flights between Nova Scotia, Canada, and the central coast of North Carolina, USA, an orthodromic distance of 2,500 km. Mean arrival to 12° latitude in South America was October 17 ± 17 days (range: September 26–November 26). Neither sex, morphological measurements, nor age significantly explained variation in nonstop flight length

Latest Documented Fall Record Of Oporornis Agilis (Connecticut Warbler) In North America

On 11 November 2017, a male hatch-year Oporornis agilis (Connecticut Warbler) was killed by a Felis catus (Domestic Cat) in Scarborough, Cumberland County, ME. This specimen, housed in the University of New England ornithological collection, is the latest documented fall record of this species in North America

Weak Effects Of Geolocators On Small Birds: A Meta-Analysis Controlled For Phylogeny And Publication Bias

Currently, the deployment of tracking devices is one of the most frequently used approaches to study movement ecology of birds. Recent miniaturization of light-level geolocators enabled studying small bird species whose migratory patterns were widely unknown. However, geolocators may reduce vital rates in tagged birds and may bias obtained movement data. There is a need for a thorough assessment of the potential tag effects on small birds, as previous meta-analyses did not evaluate unpublished data and impact of multiple life-history traits, focused mainly on large species and the number of published studies tagging small birds has increased substantially. We quantitatively reviewed 549 records extracted from 74 published and 48 unpublished studies on over 7,800 tagged and 17,800 control individuals to examine the effects of geolocator tagging on small bird species (body mass \u3c100 g). We calculated the effect of tagging on apparent survival, condition, phenology and breeding performance and identified the most important predictors of the magnitude of effect sizes. Even though the effects were not statistically significant in phylogenetically controlled models, we found a weak negative impact of geolocators on apparent survival. The negative effect on apparent survival was stronger with increasing relative load of the device and with geolocators attached using elastic harnesses. Moreover, tagging effects were stronger in smaller species. In conclusion, we found a weak effect on apparent survival of tagged birds and managed to pinpoint key aspects and drivers of tagging effects. We provide recommendations for establishing matched control group for proper effect size assessment in future studies and outline various aspects of tagging that need further investigation. Finally, our results encourage further use of geolocators on small bird species but the ethical aspects and scientific benefits should always be considered

Light-Level Geolocation Reveals The Migration Route And Non-Breeding Location Of An Antillean Nighthawk (Chordeiles Gundlachii)

The Antillean Nighthawk’s (Chordeiles gundlachii) migration routes and non-breeding location were previously unknown. We deployed a geolocator on a female Antillean Nighthawk found breeding on the Lesser Antilles island of Guadeloupe and tracked her annual movements between 2013 and 2014. Her journey included a 2-month stopover on Isla La Tortuga, Venezuela, during southward migration, and a non-breeding season in the remote forestlands of the state of Amazonas, Brazil, approximately 2,100 km south of her breeding grounds. Her migration route was geographically similar in both the fall and spring, following a north-south trajectory, but lacked a prolonged stopover in the spring

Simultaneous Incubation By Two Females And Nestling Provisioning By Four Adults At A Savannah Sparrow Nest

We present the first observations of misdirected parental care by Savannah Sparrows (Passerculus sandwichensis) including a rare occurrence of simultaneous incubation. Two females simultaneously incubated eggs, brooded, and fed nestlings, and two males fed nestlings in one nest. These behaviors may have been prompted by strong parental instincts in combination with a stressful breeding environment mediated by hayfield management, as any genetic benefits were unlikely

Stopover On Galapagos During Autumn Migration Of Bobolinks (Dolichonyx Oryzivorus)

The Bobolink (Dolichonyx oryzivorus) is the only landbird species that is known to stop every year in Galapagos while migrating; however, its stopover ecology while on the islands is unknown. In October 2015, we searched for and captured Bobolinks in the highlands of San Cristóbal. We found Bobolinks in two fields, separated by 9.15 km, at ∼425 m elevation. Average daily counts of Bobolinks on these two fields were 3.2 ± 1.8 and 4.8 ± 2.3 individuals. We caught nine individuals; body mass and fat reserves varied from 22.5–40.0 g and no fat reserves to 50–100% reserves, respectively. Both fields were dominated by grasses ranging in height from 30 cm to \u3e100 cm, and included purple cuphea (Cuphea sp.). Other habitats we surveyed, where we did not observe Bobolinks, included closely cropped grass (5–10 cm), taller grasses with seed and with scattered to dense guava trees (Psidium guajava), and small (0.1–0.3 ha) corn plantations with seed. Six of the birds we caught had seeds of Drymaria cordata entwined in their feathers; while native to the Galapagos, this plant is highly invasive in other parts of the world

Effects of Hayfield Management on Grassland Songbirds:

Over the last 40 years North American grassland bird populations have declined more than any other bird guild. This trend is especially evident in Vermont, where species experiencing precipitous declines include the Savannah Sparrow (Passerculus sandwichensis) and Bobolink (Dolichonyx oryzivorus). These declines are linked to habitat loss due to reforestation and suburbanization as well as the intensification of grassland management. Modern grassland management includes earlier first-haying dates (late-May) and shorter intervals between haying events (35 days). These management practices have severe repercussions for songbird populations because 1) early-haying results in complete nest failure (99% Savannah Sparrow and 100% Bobolink nests), 2) the interval between the first and second haying is too short for birds to renest, and 3) intensively managed fields comprise a significant portion of the total available habitat (as much as 40%). In 2002-2006, I examined how hayfield and pasture management affected grassland songbird ecological and evolutionary behavior in the agricultural landscape of the Champlain Valley, Vermont and New York. I studied songbirds in four grassland management types: early-hayed fields harvested in late-May or early-June and again in mid-July; middle-hayed fields harvested in late-June or early-July; late-hayed fields harvested after 1 August; rotationally-grazed pastures, a matrix of small paddocks where cows are moved after the grass in a paddock is eaten to a low point. I addressed the following objectives: 1. Determined the annual productivity, survival, and recruitment of Bobolinks and Savannah Sparrows in the four treatment types. 2. Identified the effects of early-haying on the social and genetic mating systems of Savannah Sparrows. 3. Conducted a population viability analysis for Bobolinks and Savannah Sparrows nesting in the Champlain Valley, assessing sensitivities of life-history parameters and identifying effective management alternatives. This study provides information on how agricultural management affects the ecology, evolution, and viability of grassland birds. It will help inform landowners, managers, and law-makers about management practices and habitat requirements needed to sustain populations

Age-Specific Differences In Fat Reserves And Migratory Passage Of Setophaga Striata (Blackpoll Warbler)

Adequate fat reserves are vital for long non-stop transatlantic avian-migration movements, such as those made by Setophaga striata (Blackpoll Warbler). Over a 5-y period, we studied differences in preparedness (determined by presence of fat content and arrival time at stopover locations) between hatch-year (HY) and after hatch-year (AHY) Blackpoll Warblers at 3 stopover sites (Hancock and York counties in Maine, and Plymouth County in Massachusetts) covering 2.65° latitude along the Gulf of Maine. Migration timing varied across a latitudinal gradient and between age classes. In September, AHY Blackpoll Warblers were more abundant in the northern and central counties, but HY birds mostly passed through in October. Compared to AHY Blackpoll Warblers, our results suggest that HY birds migrated along a more northern route. After hatch-year birds had higher fat-content than HY birds at the northern and central sites. However, AHY birds had lower fat-content at the southernmost site. After hatch-year birds were more abundant than HY birds at the southern-most site. Overall, across our study region, our data illustrate that Blackpoll Warblers show age-related differences in fall-migration strategy; hatch-year birds may simply need more time at stopover sites to build up fat reserves prior to large-distance flights

Mixed Consequences Of Divorce On Reproductive Success Of Songbirds Nesting In Agricultural Hayfields

Agricultural management, particularly haying, can cause synchronous nest failure of ground-nesting songbirds. As a consequence, these birds may subsequently renest and choose a new social mate (divorce). This study (1) quantified within-year and between-year divorce rates of grassland songbirds, and (2) determined if divorce rates differed after haying or predation-caused nest failure, and if so, whether divorce influenced reproductive success. From 2002 to 2017, we monitored 121 Bobolink (Dolichonyx oryzivorus) pairs and 436 Savannah Sparrow (Passerculus sandwichensis) pairs in an agricultural region of Vermont, USA. Within-year and between-year divorce rates were 0–84.9% for Bobolinks and 17–69.1% for Savannah Sparrows. Between years, Bobolinks, but not Savannah Sparrows, were more likely to divorce after nest failure, but haying did not influence divorce rates. Within years, Savannah Sparrows were more likely to divorce after nest failure, but as with Bobolinks, divorce rates in Savannah Sparrows were not different between nests that failed due to haying or predation. Across all Savannah Sparrow renests, divorce had no influence on the number of young fledged per female. However, between years, female Bobolinks that divorced fledged more young in their first attempt while those that did not divorce fledged more young in their second attempt. This study showed that pairing decisions were not differentially affected by cause of nest failure. Further, we identified no reproductive benefit to divorce. Our results indicate no adaptive benefit and potentially a significant reproductive cost to divorce, and that these effects vary between species