Rainfall and nest site competition delay Mountain Bluebird and Tree Swallow breeding but do not impact productivity

The Auk ◽  
2020 ◽  
Vol 137 (2) ◽  
Author(s):  
Anna Drake ◽  
Kathy Martin
Keyword(s):  
Daily Rainfall ◽  
Tree Swallow ◽  
Tree Swallows ◽  
Breeding Phenology ◽  
Productivity Cost ◽  
Breeding Sites ◽  
Tree Cavities ◽  
Mountain Bluebird ◽  
Mountain Bluebirds ◽  
Study Sites

Abstract Optimizing breeding phenology, an important aspect of fitness, is complex for migratory species as they must make key timing decisions early, and remotely, from breeding sites. We examined the role of weather (locally and cross-seasonally), cavity availability, and competitive exclusion in determining among-year variation in breeding phenology over 17 yr for 2 migratory, cavity-nesting birds: Mountain Bluebirds (Sialia currucoides; n = 462 nests) and Tree Swallows (Tachycineta bicolor; n = 572) using natural tree cavities in British Columbia, Canada. We assessed weather effects within the winter and migratory range and at our study sites. We quantified competition as the proportion of cavities occupied by European Starlings (Sturnus vulgaris) (for both species) and Mountain Bluebirds (for Tree Swallow only) in each year. For 229 bluebird and 177 swallow nests with known fates, we tested whether late years resulted in reduced productivity. Although the effects were small, heavy rainfall and strong diurnal westerly winds during migration were associated with breeding delays for Mountain Bluebirds. However, cavity availability (earlier breeding with increases) had a 5–8 × greater effect on timing than migratory conditions. There was no evidence that starling competition delayed bluebirds. In Tree Swallows, greater local daily rainfall was associated with delayed breeding, as was starling abundance (the effect of starlings was 1.4 × smaller than that of rainfall). Neither bluebird abundance nor cavity availability changed swallow phenology. Neither species showed reduced productivity in late breeding years. In both species, individuals that bred late relative to conspecifics within-year had smaller clutches and greater probability of nest failure. We conclude that breeding ground conditions, particularly cavity limitation and local rainfall (for swallows), are important drivers of breeding phenology for our focal species, but that the productivity cost of late years, at least for Tree Swallows, is minimal.

Local weather and regional climate influence breeding dynamics of Mountain Bluebirds (Sialia currucoides) and Tree Swallows (Tachycineta bicolor): a 35-year study

2017 ◽  
Vol 95 (4) ◽  
pp. 271-277 ◽  
Author(s):  
S.L. McArthur ◽  
A.E. McKellar ◽  
N.J. Flood ◽  
M.W. Reudink
Keyword(s):  
Citizen Science ◽  
Clutch Size ◽  
Regional Climate ◽  
Tachycineta Bicolor ◽  
Tree Swallow ◽  
Tree Swallows ◽  
Science Data ◽  
Sialia Currucoides ◽  
Mountain Bluebirds ◽  
Local Weather

Many songbirds are under increasing pressure owing to habitat loss, land-use changes, and rapidly changing climatic conditions. Using citizen science data collected from 1980 to 2014, we asked how local weather and regional climate influenced the breeding dynamics of Mountain Bluebirds (Sialia currucoides (Bechstein, 1798)) and Tree Swallows (Tachycineta bicolor (Vieillot, 1808)). Mountain Bluebird reproduction was strongly associated with local weather: number of nestlings and fledglings both decreased in years of high rainfall. Clutch size and number of fledglings also declined over the study period. Abundance of Mountain Bluebirds was higher in years of lower early-season snowfall and warmer local temperatures, as well as more negative Southern Oscillation Index (SOI) values, indicating a positive influence of El Niño conditions. Tree Swallow reproduction (clutch size, number of nestlings, and number of fledglings) was negatively associated with SOI values, and the number of Tree Swallow nestlings decreased in years of higher rainfall and warmer temperatures. Tree Swallows also showed a marked decline in abundance over the period of the study, consistent with recent range-wide declines. Together, our results demonstrate that local weather and regional climate differentially affect the reproductive dynamics of Mountain Bluebirds and Tree Swallows and highlight the importance of long-term citizen science data sets.

scholarly journals Recruitment, Dispersal, and Demographic Rescue in Spatially-Structured White-Tailed Ptarmigan Populations

The Condor ◽  
2000 ◽  
Vol 102 (3) ◽  
pp. 503-516 ◽  
Author(s):  
Kathy Martin ◽  
Peter B. Stacey ◽  
Clait E. Braun
Keyword(s):  
General Pattern ◽  
Population Connectivity ◽  
Site Location ◽  
Breeding Sites ◽  
Stochastic Conditions ◽  
Local Survival ◽  
Regular Event ◽  
Study Sites ◽  
One Year ◽  
Almost All

Abstract We studied recruitment and dispersal of White-tailed Ptarmigan (Lagopus leucurus) breeding in naturally fragmented alpine habitats at four study sites in Colorado from 1987–1998. Almost all recruitment for both sexes, particularly females, was of birds produced outside local populations and also external to nearby studied populations. Populations were more dependent on female recruitment than on male recruitment to sustain them, and patterns of recruitment were not correlated with local survival of adults or production of young the previous year, except at one site for females. Over 95% of recruits were yearlings. Breeding dispersal of adults, an infrequent but regular event, was also important to inter-population connectivity. Our data for multiple populations allowed us to describe movement patterns among populations to assess consistency with conditions required for a rescue system. After widespread reproductive failure in one year, we expected all populations the next year would have low recruitment due to a reduced supply of recruits produced in the region. Recruitment was low, but impact varied among populations. We conducted an over-winter study of radio-marked offspring to determine possible influences of winter site location and relatives on recruitment patterns. Contrary to expectation, offspring remained on or near breeding sites in winter, but were not located near their mothers or siblings. Recruitment location was related to winter site location. White-tailed Ptarmigan exhibit a well developed capacity for external recruitment that allows them to persist in small populations with stochastic conditions for breeding and survival. Extensive external recruitment may be a general pattern for birds.

Nest cavity availability and selection in aspen–conifer groves in a grassland landscape

2004 ◽  
Vol 34 (10) ◽  
pp. 2099-2109 ◽  
Author(s):  
Kathryn EH Aitken ◽  
Kathy Martin
Keyword(s):  
Resource Selection ◽  
Deciduous Forest ◽  
Tamiasciurus Hudsonicus ◽  
Habitat Features ◽  
Tree Cavities ◽  
Cavity Nesters ◽  
Dead Trees ◽  
Cavity Tree ◽  
Colaptes Auratus ◽  
Mountain Bluebirds

Cavity-nesting vertebrates, a significant component of forest wildlife communities, are connected ecologically in nest webs arranged in guilds of cavity producers (strong and weak excavators) and cavity consumers. The availability of tree cavities for nesting and roosting is considered critical to maintaining communities of cavity nesters. Using univariate tests and resource selection indices, we examined nesting use of both natural and excavated cavities in small aspen–conifer groves of interior British Columbia in relation to availability of cavity, tree, and habitat features. In a 2-year study, we monitored 197 cavities for use, 8% of which were lost between years. Of those that survived, 26% were occupied in both years, 29% were used in only one year, and 45% were not used in either year. Occupied cavities were larger internally than those not occupied in either year and were more likely to be in trees with only one cavity. In species-level resource selection analyses, tree swallows (Tachycineta bicolor Vieillot), European starlings (Sturnus vulgaris L.), and chickadees (Poecile spp.) used live, heart rot infected trees more than expected from their proportional abundance and used dead trees less than expected, while northern flickers (Colaptes auratus L.), mountain bluebirds (Sialia currucoides Bechstein), and red squirrels (Tamiasciurus hudsonicus Erxleben) used live and dead trees in proportion to their availability. Managed, open landscapes with small mixed or deciduous forest groves can sustain healthy communities of cavity nesters, if there is a range of suitable trees for excavators and open areas for foraging.

scholarly journals Diet of the Nestling Tree Swallow

The Condor ◽  
2004 ◽  
Vol 106 (2) ◽  
pp. 423-429 ◽  
Author(s):  
Jean M. Mengelkoch ◽  
Gerald J. Niemi ◽  
Ronald R. Regal
Keyword(s):  
Open Water ◽  
Time Of Day ◽  
Tachycineta Bicolor ◽  
Tree Swallow ◽  
Tree Swallows ◽  
Larval Stages ◽  
Terrestrial Origin ◽  
The Mean ◽  
Foraging Radius

Abstract Dietary samples from nestling Tree Swallows (Tachycineta bicolor) in northwestern Minnesota were compared to invertebrate availability as measured by aerial tow nets. The majority of the biomass in the nestlings' diet was adult insects with larval stages of aquatic origin, while absolute numbers of insects of both aquatic and terrestrial origin were similar. Orders of invertebrates in the diet and available were similar in number but not in biomass. Diet showed little variation by time of day, date of sampling or the age of the nestling. The mean number of odonates in the nestling Tree Swallows' diet increased exponentially as the percentage of open water and open water + cattail marsh increased within a 400-m foraging radius. Dieta de los Pichones de Tachycineta bicolor Resumen. Se compararon muestras dietarias de pichones de la golondrina Tachycineta bicolor tomadas en el noroeste de Minnesota con la disponibilidad de invertebrados medida con redes aéreas. La mayor parte de la biomasa en la dieta de los pichones correspondió a insectos adultos con estadíos larvales de origen acuá tico, mientras que los números absolutos de insectos de origen acuático y no acuático fueron similares. Los órdenes de invertebrados presentes en la dieta y disponibles en el ambiente fueron similares en números pero no en biomasa. La dieta mostró poca variación entre horas del día, fechas de muestreo o edad de los pichones. El número promedio de odonatos en la dieta de los pichones de T. bicolor aumentó exponencialmente a medida que se incrementó el porcentaje de agua abierta y de agua abierta + pantanos de espadañas dentro de un radio de forrajeo de 400 m.

scholarly journals Wind and rain are the primary climate factors driving changing phenology of an aerial insectivore

2017 ◽  
Vol 284 (1853) ◽  
pp. 20170412 ◽  
Author(s):  
Rachel D. Irons ◽  
April Harding Scurr ◽  
Alexandra P. Rose ◽  
Julie C. Hagelin ◽  
Tricia Blake ◽  
...  
Keyword(s):  
Climate Change ◽  
Natural Populations ◽  
Climate Change Impacts ◽  
Tree Swallow ◽  
Breeding Phenology ◽  
Climate Conditions ◽  
Aerial Insectivore ◽  
Windy Weather ◽  
Two Measures

While the ecological effects of climate change have been widely observed, most efforts to document these impacts in terrestrial systems have concentrated on the impacts of temperature. We used tree swallow ( Tachycineta bicolor ) nest observations from two widely separated sites in central Alaska to examine the aspects of climate affecting breeding phenology at the northern extent of this species' range. We found that two measures of breeding phenology, annual lay and hatch dates, are more strongly predicted by windiness and precipitation than by temperature. At our longest-monitored site, breeding phenology has advanced at nearly twice the rate seen in more southern populations, and these changes correspond to long-term declines in windiness. Overall, adverse spring climate conditions known to negatively impact foraging success of swallows (wet, windy weather) appear to influence breeding phenology more than variation in temperature. Separate analyses show that short windy periods significantly delay initiation of individual clutches within years. While past reviews have emphasized that increasing variability in climate conditions may create physiological and ecological challenges for natural populations, we find that long-term reductions in inclement weather corresponded to earlier reproduction in one of our study populations. To better predict climate change impacts, ecologists need to more carefully test effects of multiple climate variables, including some, like windiness, that may be of paramount importance to some species, but have rarely been considered as strong drivers of ecological responses to climate alteration.

Organochlorine Contaminants in Avian Wildlife of Severn Sound

1995 ◽  
Vol 30 (4) ◽  
pp. 693-712 ◽  
Author(s):  
Pamela A. Martin ◽  
D. Vaughn Weseloh ◽  
Christine A. Bishop ◽  
Karin Legierse ◽  
Birgit Braune ◽  
...  
Keyword(s):  
Lake Ontario ◽  
Lake Huron ◽  
Breast Muscle ◽  
Tree Swallow ◽  
Tree Swallows ◽  
Herring Gulls ◽  
Terrestrial Arthropods ◽  
Common Terns ◽  
Organochlorine Contaminants ◽  
Caspian Terns

Abstract Organochlorine contaminants were measured in pooled egg samples of colonial waterbirds, red-winged blackbirds and tree swallows breeding in or near Severn Sound, Lake Huron, an area designated by the International Joint Commission as an Area of Concern, during 1991. Breast muscle samples of staging waterfowl were also collected the preceding autumn. PCBs, DDE and mirex were the most prevalent organochlorine contaminants present in eggs (concentration ranges of 0.065 to 5.452, 0.118 to 3.12 and 0.007 to 0.174 mg/kg, respectively), while oxychlordane, cis-chlordane, dieldrin, heptachlor epoxide, trans-nonachlor, cis-nonachlor, OCS, HCB and beta-HCH were also detectable at low levels in some egg samples. Tetra- and pentachlorobenzene, and alpha-and gamma-HCH were not detected in any of the samples. Generally, the following interspecific gradient in contaminant levels in bird eggs was found: herring gulls = Caspian terns > common terns > tree swallows > blackbirds. Concentrations in the eggs of piscivorous birds in Severn Sound were similar or slightly lower than those from other colonies in Georgian Bay and Lake Huron, and considerably lower than those from colonies in Hamilton Harbour, Lake Ontario. Mirex levels in herring gulls and Caspian terns from Severn Sound colonies were an exception in that they were substantially higher than levels from other Lake Huron colonies (0.174 and 0.167 mg.kg-1 for the two species, respectively, versus <0.12 mg.kg-1), although still much lower than those from Lake Ontario (0.50 and 0.719, respectively). It is probable that mirex was accumulated by gulls and terns during winter or migrational stopovers on Lake Ontario. Low contaminant levels in common terns may have been a result of their consumption of a smaller size class of prey fish. Higher contaminant levels in tree swallow eggs in comparison to red-winged blackbird eggs may have been due to the preponderance of aquatic insects in their diets, as opposed to the larger proportion of terrestrial arthropods in blackbird diets. Only PCBs and DDE were detected in the breast muscle of lesser scaup and mallards.

scholarly journals A meta-analysis of relationships between polychlorinated biphenyl exposure and performance across studies of free-ranging tree swallows ( Tachycineta bicolor )

2016 ◽  
Vol 3 (4) ◽  
pp. 150634 ◽  
Author(s):  
Frances Bonier
Keyword(s):  
Reproductive Success ◽  
Polychlorinated Biphenyl ◽  
Meta Analysis ◽  
Field Studies ◽  
Tree Swallow ◽  
Tree Swallows ◽  
Bioindicator Species ◽  
And Performance ◽  
Free Ranging ◽  
Pcb Exposure

Habitats worldwide are increasingly being degraded by human activities, with environmental pollution representing a significant threat to species and ecosystems. The presence of persistent organic chemicals, such as polychlorinated biphenyls (PCBs), has generated concern. Captive experiments and field studies have reported some evidence for detrimental effects of PCB exposure, but also significant variation across studies and species. Here, I use a meta-analytical approach to combine findings across 10 studies investigating effects of PCBs on performance (e.g. reproductive success, offspring growth) in free-ranging tree swallows, a common bioindicator species that accumulates high levels of PCBs at some contaminated sites. Contrary to predictions, five complementary analyses revealed no significant negative association between PCB exposure and performance in tree swallows. In fact, in one analysis, increased PCB exposure was associated with improved reproductive success. Possible explanations for these findings include several limitations of field studies, variation in the toxicity of different PCB congener mixtures found across sites included in the analysis, and variation in the degree of tolerance of PCB exposure among species (with high tolerance found in tree swallows). At this point, the available evidence from field studies does not demonstrate negative impacts of PCB exposure on tree swallow performance.

scholarly journals Butterfly Diversity from Farmlands of Central Uganda

2012 ◽  
Vol 2012 ◽  
pp. 1-23 ◽  
Author(s):  
M. B. Théodore Munyuli
Keyword(s):  
Abundant Species ◽  
Agroforestry Systems ◽  
Agricultural Landscapes ◽  
Cultivated Plants ◽  
Line Transect ◽  
Breeding Sites ◽  
Forest Reserves ◽  
Forest Remnants ◽  
Study Sites ◽  
One Year

The aim of this study was to collect information about the diversity of butterfly communities in the mixed coffee-banana mosaic (seminatural, agricultural) landscapes of rural central Uganda. Data were collected for one year (2006) using fruit-bait traps, line transect walk-and-counts, and hand nets. A total of 56,315 individuals belonging to 331 species, 95 genera, and 6 families were sampled. The most abundant species wasBicyclus safitza(14.5%) followed byAcraea acerata(6.3%),Catopsilia florella(6.5%) andJunonia sophia(6.1%). Significant differences in abundance, species richness, and diversity of butterflies occurred between the 26 study sites. Farmland butterflies visited a variety of habitats within and around sites, but important habitats included woodlands, fallows, hedgerows, swampy habitats, abandoned gardens, and home gardens. The highest diversity and abundance of butterflies occurred in sites that contained forest remnants. Thus, forest reserves in the surrounding of fields increased the conservation values of coffee-banana agroforestry systems for butterflies. Their protection from degradation should be a priority for policy makers since they support a species-rich community of butterflies pollinating cultivated plants. Farmers are encouraged to protect and increase on-farm areas covered by complex traditional agroforests, linear, and nonlinear seminatural habitats to provide sufficient breeding sites and nectar resources for butterflies.

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