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Vast areas of North American grasslands have been lost and degraded, resulting in unprecedented declines of biodiversity. For example, 82% of North American grassland songbird species are experiencing population declines. Basic natural history, life history, and demographic data from different regions and time periods are essential for modeling population dynamics and developing effective conservation strategies for grassland birds. We monitored 392 nests to provide information on nesting biology, quantify reproductive success, and gain insight into the extent to which predation and weather influence nest survival of 7 grassland songbird species in southwest Saskatchewan, during 2010 and 2011. Clutch sizes of all species were within the range reported previously and declined as the breeding season progressed, particularly for Chestnut-collared Longspur (Calcarius ornatus), Vesper (Pooecetes gramineus) and Baird's (Centronyx bairdii) sparrows, and Western Meadowlark (Sturnella neglecta). Overall, 32–69% of the nests we monitored were depredated, and predation accounted for 91% of all unsuccessful nesting attempts. Daily survival rates were lowest during the nestling stage for 5 species, and nest survival estimates ranged from 16% to 48%. Nest survival of 4 species was influenced by the temporal effects of age and date. Chestnut-collared Longspur and Western Meadowlark nest survival increased through early to mid-incubation and declined thereafter until ∼3 d prior to fledging before increasing again. Nest survival of these 2 species, along with Sprague's Pipit (Anthus spragueii) and Vesper Sparrow, were lowest in late June to early July. We found no support for a strong effect of precipitation on nest survival. However, nest survival rates declined with increasing ambient temperature for Chestnut-collared Longspur and Horned Lark (Eremophila alpestris), the 2 study species with the most exposed nests, and were highest for Western Meadowlark nests when ambient temperatures were between 15 and 24 °C. [ABSTRACT FROM AUTHOR]

Compared to mammals, there are relatively few studies examining heterothermy in birds. In 13 bird families known to contain heterothermic species, the common poorwill (Phalaenoptilus nuttallii) is the only species that ostensibly hibernates. We used temperature-sensitive radio-transmitters to collect roost and skin temperature (Tskin) data, and winter roost preferences for free-ranging poorwills in southern Arizona. Further, to determine the effect of passive rewarming on torpor bout duration and active rewarming (i.e., the use of metabolic heat to increase Tskin), we experimentally shaded seven birds during winter to prevent them from passively rewarming via solar radiation. Poorwills selected winter roosts that were open to the south or southwest, facilitating passive solar warming in the late afternoon. Shaded birds actively rewarmed following at least 3 days of continuous torpor. Average torpor bout duration by shaded birds was 122 h and ranged from 91 to 164 h. Active rewarming by shaded birds occurred on significantly warmer days than those when poorwills remained torpid. One shaded bird remained inactive for 45 days, during which it spontaneously rewarmed actively on eight occasions. Our findings show that during winter poorwills exhibit physiological patterns and active rewarming similar to hibernating mammals. [ABSTRACT FROM AUTHOR]

The article presents study which investigates the song rate variation within individual Sprague's pipit (Anthus Spragueii). The study shows the association of high song rates with increased mating events, flock dominance, and increased offspring paternity. It notes that song rate variation within individual males indicates the influence of external factors to song rates. It points out that song rates vary with environmental conditions, breeding stage, and time of day. The results warrant further study in identifying factors may be attributed for the variation.

Grassland birds have undergone widespread global population declines due to loss and degradation of native grasslands. Activities associated with non-renewable energy derived from oil and natural gas extraction have substantially increased on grasslands. The cumulative disturbance generated by natural gas development creates a network of non-linear (e.g., bare ground and exotic plant species) and linear (e.g., roads, trails, pipelines) features that may degrade habitat quality for grassland species. We quantified grassland songbird abundance in two areas of southwestern Saskatchewan, Canada, to determine whether variation in abundance 1) depended on the type and amount of disturbance at two spatial extents, and 2) was more affected by the cumulative impacts of natural gas development than any single type of disturbance. We found that specific types of disturbances impacted the abundance of most species to varying degrees. The cover of different types of linear disturbance had the strongest effect on the most species. Natural gas disturbance within 450 m of point counts was more influential than disturbance within 200 m for nearly all species in both areas. Only Savannah sparrow (Passerculus sandwichensis) abundance was most strongly influenced by the cumulative amount of disturbance with abundance decreasing with increased disturbance. Overall, we detected few consistent patterns among species, or within species between our two study areas. Our results indicated that the impact of natural gas infrastructure can extend beyond the local influences associated with well sites and that relatively small amounts of disturbance (<2%) may impact grassland songbird abundance. We recommend that researchers use caution when studying well-density effects or combining individual types of disturbance without understanding the separate effects each type of disturbance has on the species or community of interest. Not doing so may lead to investing resources into management practices that do not have the greatest possible benefit for grassland songbirds. [ABSTRACT FROM AUTHOR]

Many bird species will attempt to raise more than one clutch in a given breeding season. For grassland songbirds, the interval between nesting attempts is usually measured indirectly because individual birds are difficult to track once a nest has failed or their chicks have fledged. Here we report observations of renesting by Sprague's Pipits(Anthus spragueii) carrying radio transmitters. As part of a larger study of pipit nesting ecology, we monitored activity patterns of radio-tagged adult females in 1994 and 1995. Three birds started replacement nests 10--15 days after losing a clutch, and one started a second nest 21 days after successfully fledging chicks. Such long intervals between nesting attempts support the impression that the frequency of renesting in pipits is relatively low. [ABSTRACT FROM AUTHOR]

We observed 56 forced copulation (FC) events in a breeding colony of American White Pelicans (Pelecanus erythrorhynchos) in Saskatchewan, Canada during the 2005 nesting season. All FCs were directed at nestlings >21 days of age that were not continuously attended by an adult. The onset of FCs occurred in close synchrony with an unexpected late-season increase in adult copulation attempts. We suggest that FC directed at nestlings is not simply an aberrant and non-adaptive behavior. Rather, copulations with nestlings result from adult male pelicans being inappropriately stimulated to copulate with nestlings when actually seeking copulations with adult females. [ABSTRACT FROM AUTHOR]

Migratory connectivity is the degree to which populations are linked in space and time across the annual cycle. Low connectivity indicates mixing of populations while high connectivity indicates population separation in space or time. High migratory connectivity makes individual populations susceptible to local environmental conditions; therefore, evaluating migratory connectivity continuously across a species range is important for understanding differential population trends and revealing places and times contributing to these differences. The common nighthawk Chordeiles minor is a widespread, declining, long‐distance migratory bird. Variable population trends across the nighthawk breeding range suggest that knowledge of migratory connectivity is needed to direct conservation. We used GPS tags to track 52 individuals from 12 breeding populations. We estimated migratory connectivity as 0.29 (Mantel coefficient: 0 = no connectivity, 1 = full connectivity) between the breeding and wintering grounds. We then estimated migratory connectivity at every latitude (spatial connectivity) or day (temporal connectivity) of migration and smoothed those migratory connectivity estimates to produce continuous migratory connectivity 'profiles'. Spatial and temporal connectivity were highest during migration through North America (around 0.3–0.6), with values generally around 0 in Central and South America due to mixing of populations along a common migratory route and similar migration timing across populations. We found local peaks in spatial and temporal connectivity during migration associated with crossing the Gulf of Mexico. We used simulations to estimate the probability that our method missed peaks (spatial: 0.12, temporal: 0.18) or detected false peaks (spatial: 0.11, temporal: 0.37) due to data gaps and showed that our approach remains useful even for sparse and/or sporadic location data. Our study presents a generalizable approach to evaluating migratory connectivity across the full annual cycle that can be used to focus migratory bird conservation towards places and times of the annual cycle where populations are more likely to be limited. [ABSTRACT FROM AUTHOR]

Presents a study which aims to compare diet of common nighthawks (Chordeiles minor) with a measure of prey abundance. Study site; Analysis of nighthawk's diet; Results of the study.

Hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans) are species of conservation concern because of the documented annual mortality that occurs at wind energy facilities. Several recent studies have predicted continental-scale declines of hoary bat populations due to interactions with wind turbines. We predicted a decrease in captures at a summer site over 20 years where researchers have captured bats using generally consistent methods. We developed a hierarchical Bayesian model to estimate the relative change in the expected number of captures while controlling for time of year, temperature, and netting effort. We found no decrease in the number of captures for either species. We suggest that the lack of decrease observed at our study site may be a result of compensatory immigration, despite potential broader-scale population declines. [ABSTRACT FROM AUTHOR]