Nest-Site Selection by Female Black-Capped Chickadees: Settlement Based on Conspecific Attraction?

Female Black-capped Chickadees (Poecile atricapillus) solicit extrapair copulations (EPCs) from neighboring high-ranking males, and these EPCs result in extrapair young. Females might choose to locate their nests near the territory boundaries of attractive males to facilitate access to EPCs. Other hypotheses might also explain choice of nest site, namely (1) habitat characteristics, (2) prey abundance, and (3) previous experience. We tested these four hypotheses in 1996 and 1997. Out of 27 habitat characteristics measured, we found only one that was significantly different between nests and control sites in both years. The abundance of large trees was lower at nest sites than at control sites in each year and when years were pooled. Relative prey abundance did not differ between nests and control sites for either year of the study. We found no different in interyear nest placement based on female experience; experienced females nester farther than 60 m from their previous nest sites in both years of the study. In 1996, females whose neighboring males were higher ranked than their social partner located their nests significantly closer to territory boundaries than did females whose nearest neighbors were lower ranked than their social partner. In 1997, all pairs nested near territory boundaries. We conclude that choice of nest location in Black-capped Chickadees is influenced by conspecific attraction based on mating tactics

Between-Year Survival and Rank Transitions in Male Black-Capped Chickadees (\u3cem\u3ePoecile Atricapillus\u3c/em\u3e): A Multistate Modeling Approach

In dominance-structured animal societies, variation in individual fitness is often related to social status. Like many passerine birds, Black-capped Chickadees (Poecile atricapillus) have a short average adult life-expectancy (Ø2 years); however, the maximum recorded life span is \u3e5× as long. Enhanced annual survival could contribute to greater lifetime reproductive success for male Black-capped Chickadees with high social rank. We used multistate capture–mark–recapture models to estimate annual survival of male Black-capped Chickadees in Ontario using resighting and recapture data collected from 1997 to 2002. Our goal was to evaluate support for an influence of rank on annual survival and estimate its effect size for a food-supplemented study site. We also statistically modeled the probability of between-year rank transitions. Model selection based on Akaike’s information criterion provided support for an effect of rank on survival. However, multimodel inference revealed that the size of the effect was rather small. Over the six study years, model-averaged estimates of the survival benefit of high versus low rank ranged from 5.0 to 7.3%. As expected, survival was strongly year-dependent, with model-averaged estimates of annual survival probability varying between 0.36 and 0.73. Age was an important predictor of the probability of rank transitions. Low-ranked second-year birds were less likely than older low-ranked birds to advance to high rank between years; likewise, high-ranked after-second-year birds were less likely to drop in rank. Other studies have found larger effects of rank on survival than we observed here. Future research should consider how interactions between social and environmental factors influence annual survival

Enhanced Reproductive Success of Female Black-Capped Chickadees Mated to High-Ranking Males

Overwinter survival of female Black-capped Chickadees (Poecile atricapillus) depends in part on the rank of their mates. We investigated whether females also gain reproductive beenfits by pairing with high-ranking males. We assessed breeding success in 1993 to 1995 and 1997 by comparing clutch size, proportion of eggs hatched, hatching date, and prediction rates on nests of females mated to either high-ranking or low-ranking males. We also compared feeding rates of males to incubating females and to offspring during the early nestling period in 1994 and 1995. High-ranking and low-ranking males did not differ in feeding rates during early incubation or early nestling stages. Females mated to high-ranking males incubated for longer periods than females mated ot low-ranking males. Younger males and females mated to low-ranking males fed nestlings at a higher rate than did older males and females mated to high-ranking males, respectively. Females mated ot high-ranking males had larger clutches, hatched a significantly greater proportion of their eggs, and suffered lower nest predation than females mated to low-ranking males. In 1995 and 1997, where the ranks and ages of both members of 23 pairs were known, female rank was strongly correlated with mate rank and age but was only weakly associated with female age. Female rank accounted for significant variation only in clutch size, and male rank accounted for a greater proportion of variation in clutch size and fleding success than did the female’s own rank

Enhanced Reproductive Success of Female Black-Capped Chickadees Mated to High-Ranking Males

Overwinter survival of female Black-capped Chickadees (Poecile atricapillus) depends in part on the rank of their mates. We investigated whether females also gain reproductive beenfits by pairing with high-ranking males. We assessed breeding success in 1993 to 1995 and 1997 by comparing clutch size, proportion of eggs hatched, hatching date, and prediction rates on nests of females mated to either high-ranking or low-ranking males. We also compared feeding rates of males to incubating females and to offspring during the early nestling period in 1994 and 1995. High-ranking and low-ranking males did not differ in feeding rates during early incubation or early nestling stages. Females mated to high-ranking males incubated for longer periods than females mated ot low-ranking males. Younger males and females mated to low-ranking males fed nestlings at a higher rate than did older males and females mated to high-ranking males, respectively. Females mated ot high-ranking males had larger clutches, hatched a significantly greater proportion of their eggs, and suffered lower nest predation than females mated to low-ranking males. In 1995 and 1997, where the ranks and ages of both members of 23 pairs were known, female rank was strongly correlated with mate rank and age but was only weakly associated with female age. Female rank accounted for significant variation only in clutch size, and male rank accounted for a greater proportion of variation in clutch size and fleding success than did the female’s own rank

More on the Burkhardt-Cottingham Sum Rule in QCD

The QCD higher order effects to the polarized structure function $g_2(x, Q^2 )$ are reanalyzed for massive quarks in the context of the operator product expansion. We confirm that the lowest moment of $g_2 (x, Q^2 )$ which corresponds to the Burkhardt-Cottingham sum rule does {\sl not} suffer from radiative corrections in perturbative QCD.Comment: LaTeX, 9 pages, 1 figure appended after \end{document} as an uu-encoded and compressed .ps file, KUCP-70;HUPD-9410;YNU-HEPTh-94-10

The mobility of experiential learning pedagogy: transferring ideas and practices from a large- to a small-campus setting

In this article, we examine the development of a new, experiential learning human geography and planning course at a smaller campus in Newfoundland, Canada. Our interest is twofold: to consider how pedagogical approaches can be transferred between a large urban campus and a small-town location; and to examine the benefits and complications of such transfers through a reflective examination of the resulting experiential learning program. The article captures the experiences of students, faculty, and university engagement staff in the deployment of the course. From these perspectives, we situate the decision to transfer an existing program across universities, the nuances of adapting such programs to the local context, and the challenge of meeting student desires for experiential learning amidst experimental pedagogical approaches. The paper concludes by suggesting that transferring pedagogical models across locations requires flexibility in terms of ensuring that new modules fit existing program constraints, and that such transfers have the potential to both challenge and positively transform experiential learning processes

Between-year survival and rank transitions in male black-capped chickadees (Poecile atricapillus): A multistate modeling approach

In dominance-structured animal societies, variation in individual fitness is often related to social status. Like many passerine birds, Black-capped Chickadees (Poecile atricapillus) have a short average adult life-expectancy (∼2 years); however, the maximum recorded life span is \u3e 5× as long. Enhanced annual survival could contribute to greater lifetime reproductive success for male Black-capped Chickadees with high social rank. We used multistate capture-mark-recapture models to estimate annual survival of male Black-capped Chickadees in Ontario using resighting and recapture data collected from 1997 to 2002. Our goal was to evaluate support for an influence of rank on annual survival and estimate its effect size for a food-supplemented study site. We also statistically modeled the probability of between-year rank transitions. Model selection based on Akaike\u27s information criterion provided support for an effect of rank on survival. However, multimodel inference revealed that the size of the effect was rather small. Over the six study years, model-averaged estimates of the survival benefit of high versus low rank ranged from 5.0 to 7.3%. As expected, survival was strongly year-dependent, with model-averaged estimates of annual survival probability varying between 0.36 and 0.73. Age was an important predictor of the probability of rank transitions. Low-ranked second-year birds were less likely than older low-ranked birds to advance to high rank between years; likewise, high-ranked after-second-year birds were less likely to drop in rank. Other studies have found larger effects of rank on survival than we observed here. Future research should consider how interactions between social and environmental factors influence annual survival. © The American Ornithologists\u27 Union, 2008

Individual repeatability of avian migration phenology: a systematic review and meta-analysis

Changes in phenology and distribution are being widely reported for many migratory species in response to shifting environmental conditions. Understanding these changes and the situations in which they occur can be aided by understanding consistent individual differences in phenology and distribution and the situations in which consistency varies in strength or detectability. Studies tracking the same individuals over consecutive years are increasingly reporting migratory timings to be a repeatable trait, suggesting that flexible individual responses to environmental conditions may contribute little to population-level changes in phenology and distribution. However, how this varies across species and sexes, across the annual cycle and in relation to study (tracking method, study design) and/or ecosystem characteristics is not yet clear. Here, we take advantage of the growing number of publications in movement ecology to perform a phylogenetic multilevel meta-analysis of repeatability estimates for avian migratory timings to investigate these questions. Of 2,433 reviewed studies, 54 contained suitable information for meta-analysis, resulting in 177 effect sizes from 47 species. Individual repeatability of avian migratory timings averaged 0.414 (95% confidence interval: 0.3-0.5) across landbirds, waterbirds and seabirds, suggesting consistent individual differences in migratory timings is a common feature of migratory systems. Timing of departure from the non-breeding grounds was more repeatable than timings of arrival at or departure from breeding grounds, suggesting that conditions encountered on migratory journeys and outcome of breeding attempts can influence individual variation. Population-level shifts in phenology could arise through individual timings changing with environmental conditions and/or through shifts in the numbers of individuals with different timings. Our findings suggest that, in addition to identifying the conditions associated with individual variation in phenology, exploring the causes of between-individual variation will be key in predicting future rates and directions of changes in migratory timings. We therefore encourage researchers to report the within- and between- individual variance components underpinning the reported repeatability estimates to aid interpretation of migration behaviour. In addition, the lack of studies in the tropics means that levels of repeatability in less strongly seasonal environments are not yet clear

Upper Kellwasser carbon isotope excursion pre-dates the F–F boundary in the Upper Devonian Lennard shelf carbonate system, Canning Basin, Western Australia

Here we report four high-resolution carbon isotope records in addition to trace element data for the Frasnian–Famennian (F–F) boundary interval in the Lennard Shelf carbonate system of the Canning Basin, Western Australia. This region lacks the characteristic black shale horizons associated with the global Late Devonian Kellwasser extinction events, yet still exhibits a trend in carbon isotope character similar to what has been reported from elsewhere in the world (two positive δ13C excursions with ~3–4‰ amplitudes). Enrichments in select trace element ratios suggest that both excursions are related to periods of oxygen deprivation and perhaps increased biological productivity. Given the continuous and stratigraphically expanded nature of Lennard Shelf sections, together with high-density sampling constrained by both conodont biostratigraphy and magnetostratigraphy, we observe that the Upper Kellwasser isotope excursion (maximum δ13C values) and associated trace element enrichments occur distinctly lower than the F–F boundary level. These results have implications for the paleoenvironmental conditions leading up to the Late Devonian Mass Extinction in terms of ocean chemistry and circulation patterns. This data set allows for a rare, detailed look at the temporal relationship between the Kellwasser events and the F–F boundary and constrains the pattern of carbon isotope perturbations at the intra-zonal scale