scholarly journals Does Increasing Daylength Control Seasonal Changes in Clutch Sizes of Northern Pintails (Anas Acuta)?

The Auk ◽  
2002 ◽  
Vol 119 (2) ◽  
pp. 498-506 ◽  
Author(s):  
Gary L. Krapu ◽  
Glen A. Sargeant ◽  
Alison E. H. Perkins
Keyword(s):  
North Dakota ◽  
Survival Rates ◽  
Day Length ◽  
Population Declines ◽  
Anas Acuta ◽  
Breeding Grounds ◽  
Northern Pintails ◽  
Rate Of Decline ◽  
Seasonal Decline ◽  
Nesting Season

AbstractWe evaluated spatiotemporal variation in clutch sizes of Northern Pintails (pintails; Anas acuta) nesting in California (1985 to 1996), North Dakota (1982 to 1985), Saskatchewan (1982 to 1985) and Alaska (1991 to 1993) to determine whether seasonal declines in clutch size varied in ways that were consistent with a controlling influence of increasing day length. Pintails began nesting in mid-March in California, mid-April in North Dakota and Saskatchewan, and mid-May in Alaska. Observed durations of nesting were 70 ± 2.6 days (SE) in California, 60 ± 6.3 days in North Dakota, 66 ± 1.3 days in Saskatchewan, and 42 ± 0.7 days in Alaska. Annual differences were the principal source of variation in mean clutch sizes (σ̂Y2 = 0.15, SE = 0.049), which varied little among study locations (σ̂A2 = 0.002, SE = 0.013). Predicted rates of seasonal decline in clutch sizes increased with latitude early in the nesting season, but declined as the nesting season progressed, except in California. Rates of decline in clutch sizes thus were not directly related to rates of increase in day length. Predicted declines in numbers of eggs per clutch over the nesting season were similar for all four locations (range, 3.05–3.12) despite wide variation in durations of nesting. Evidence suggests that reduced nutrient availability during nesting contributes to a higher rate of decline in clutch sizes in Alaska than in temperate regions. Pintails that nest early lay large initial clutches, but thereafter clutch sizes decline rapidly and breeding terminates early. This reproductive strategy is adaptive because young that hatch earliest exhibit the highest survival rates; however, the conversion of grassland to cropland on the primary prairie breeding grounds has reduced hatching rates of clutches laid early in the nesting season. Under these conditions, the limited capacity to renest in late spring on their prairie breeding grounds probably has contributed to Pintail population declines.

Effects of anthropogenic and environmental stress on the corticosterone levels of wintering Northern Pintails (Anas acuta)

2014 ◽  
Vol 92 (3) ◽  
pp. 185-193 ◽  
Author(s):  
D.P. Taylor ◽  
J.N. Vradenburg ◽  
L.M. Smith ◽  
M.B. Lovern ◽  
S.T. McMurry
Keyword(s):  
Maximum Stress ◽  
Survival Rates ◽  
Late Winter ◽  
Anas Acuta ◽  
Winter Activity ◽  
Wintering Areas ◽  
Corticosterone Response ◽  
Northern Pintails ◽  
The Relationship ◽  
Pituitary Adrenal Axis

Winter-specific survival rates for female Northern Pintails (Anas acuta L., 1758; hereafter “Pintails”) at the Bosque del Apache National Wildlife Refuge were found in a previous study to be low relative to other wintering areas, raising concerns that tourism could be impacting the health of the population. Measurements of corticosterone levels enable the assessment and quantification of human-induced stressors that can ultimately affect fitness. We analyzed corticosterone concentrations and the relationship between body condition and maximum stress-induced corticosterone in areas with and without tourism access. Female Pintails were captured in winters of 2008–2009 and 2009–2010. The corticosterone response was similar between areas with and without tourism, but different between winters. In mid-January 2010, levels were 73% greater after 60 min compared with those in 2009. A greater stress response in mid-January 2010 may have been due to colder temperatures and arriving later and in poorer condition. Also in 2009–2010, there was a negative correlation between carcass fat and maximum corticosterone, possibly in response to colder temperatures, arriving in poorer condition, or a combination of both. Our study indicates that in mid- to late winter, activity of the hypothalamic–pituitary–adrenal axis may be higher during winters with comparatively greater environmental hardships, emphasizing the importance of carefully managing waterfowl during periods when they are most sensitive.

scholarly journals Preliminary survival and movement data for a declining population of Flesh-footed Shearwater Ardenna carneipes in Western Australia provides insights into marine threats

2018 ◽  
Vol 29 (2) ◽  
pp. 327-337 ◽  
Author(s):  
JENNIFER L. LAVERS ◽  
SIMEON LISOVSKI ◽  
ALEXANDER L. BOND
Keyword(s):  
Western Australia ◽  
Survival Rates ◽  
Adult Survival ◽  
Seabird Species ◽  
Movement Data ◽  
Central Indian Ocean ◽  
Breeding Grounds ◽  
Wintering Areas ◽  
Fisheries Bycatch ◽  
Western Australian

SummarySeabirds face diverse threats on their breeding islands and while at sea. Human activities have been linked to the decline of seabird populations, yet over-wintering areas typically receive little or no protection. Adult survival rates, a crucial parameter for population persistence in long-lived species, tend to be spatially or temporally restricted for many seabird species, limiting our understanding of factors driving population trends at some sites. We used bio-loggers to study the migration of Western Australian Flesh-footed Shearwaters Ardenna carneipes carneipes and estimated adult survival over five years. Western Australia is home to around 35% of the world’s breeding Flesh-footed Shearwaters, a population which was up-listed to Vulnerable in 2015. During the austral winter, shearwaters migrated across the central Indian Ocean to their non-breeding grounds off western Sri Lanka. Low site fidelity on breeding islands, mortality of adult birds at sea (e.g. fisheries bycatch), and low annual breeding frequency likely contributed to the low estimated annual adult survival (2011–2015: ϕ = 0.634-0.835).

Endogenous biomarkers reveal diet partitioning among three sympatric species of swallows

The Auk ◽  
2021 ◽  
Author(s):  
Kaelyn H Bumelis ◽  
Michael D Cadman ◽  
Keith A Hobson
Keyword(s):  
Isotope Analysis ◽  
Sympatric Species ◽  
Tree Swallow ◽  
Population Declines ◽  
Interspecific Differences ◽  
Cliff Swallow ◽  
Aerial Insectivores ◽  
Breeding Grounds ◽  
Potential Factors ◽  
Δ 15N

Abstract Since the early 1990s, aerial insectivorous birds have shown serious population declines in North America, but it is not clear if factors common to all species within this guild account for these declines. Among sympatric swallows, population trends differ, and this may be due to differences in ecology operating throughout the annual cycle. Although these species all feed on aerial insects, prey taxa can differ tremendously in their “aeroecology” and use by swallows. We examined the potential for dietary differences among three species of swallows, Barn Swallow (Hirundo rustica), Cliff Swallow (Petrochelidon pyrrhonota), and Tree Swallow (Tachycineta bicolor), breeding sympatrically in southern Ontario, Canada. Potential interspecific differences in nestling diet were examined using two endogenous biomarkers, DNA barcoding of nestling feces and stable isotope analysis (δ 2H, δ 13C, δ 15N) of nestling feathers. We found evidence for differences in dietary sources of provisioned young where Barn Swallows provisioned more terrestrial-based prey, Cliff Swallows provisioned an intermediate diet, and Tree Swallows the most aquatic-emergent insect diet. We suggest this information may help to identify potential factors contributing to differential declines of aerial insectivores operating on the breeding grounds, including diet quality.

scholarly journals Fat Dynamics of Arctic-Nesting Sandpipers During Spring in Mid-Continental North America

The Auk ◽  
2006 ◽  
Vol 123 (2) ◽  
pp. 323-334
Author(s):  
Gary L. Krapu ◽  
Jan L. Eldridge ◽  
Cheri L. Gratto-Trevor ◽  
Deborah A. Buhl
Keyword(s):  
North America ◽  
North Dakota ◽  
Body Fat ◽  
Prairie Pothole Region ◽  
Energy Requirements ◽  
Prairie Pothole ◽  
Male And Female ◽  
Total Body Fat ◽  
Breeding Grounds ◽  
Total Body

Abstract We measured fresh body mass, total body fat, and fat-free dry mass (FFDM) of three species of Arctic-nesting calidrid sandpipers (Baird's Sandpiper [Calidris bairdii], hereafter “BASA”; Semipalmated Sandpiper [C. pusilla], hereafter “SESA”; and White-rumped Sandpiper [C. fuscicollis], hereafter “WRSA”) during spring stopovers in the Prairie Pothole Region (PPR) of North Dakota, and evaluated the contribution of stored fat to (1) energy requirements for migration to their Arctic-breeding grounds and (2) nutrient needs for reproduction. All spring migrant WRSA (n = 124) and BASA (n = 111), and all but 2 of 99 SESA we collected were ≥2 years old. Male and female BASA migrated through North Dakota concurrently, male SESA averaged earlier than females, and WRSA males preceded females. Fat indices (ratio of fat to FFDM) of male and female SESA and WRSA averaged approximately twice those of male and female BASA. Total body fat of male and female BASA increased with date in spring 1980, but not in 1981; slopes were similar for both sexes each year. Male and female SESA arrived lean in 1980 and 1981, and total body fat increased with date in both years, with similar slopes for all combinations of sex and year. Male and female WRSA arrived lean in 1980–1981 and 1981, respectively, and total body fat increased with date, whereas females arrived with fat reserves already acquired in 1980. Interspecific and sex differences in migration schedules probably contributed to variation in fat storage patterns by affecting maintenance energy costs and food availability. Estimated flight ranges of BASA suggest that few could have met their energy needs for migration to the breeding grounds exclusively from fat stored by the time of departure from North Dakota. Estimated flight ranges of SESA and WRSA, along with fresh body masses of both species when live-trapped on or near their breeding grounds in northern Canada, suggest that major parts of both populations stored adequate fat by departure from temperate mid-continental North America to meet their energy requirements for migration and part of their nutrient needs for reproduction. Dinámica de la Grasa en Chorlos que Nidifican en el Ártico durante la Primavera en el Área Continental Central de América del Norte

scholarly journals Population decline and range contraction of the Egyptian Vulture Neophron percnopterus in the Balkan Peninsula

2014 ◽  
Vol 25 (4) ◽  
pp. 440-450 ◽  
Author(s):  
METODIJA VELEVSKI ◽  
STOYAN C. NIKOLOV ◽  
BEN HALLMANN ◽  
VLADIMIR DOBREV ◽  
LAVRENTIS SIDIROPOULOS ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Population Decline ◽  
Balkan Peninsula ◽  
Population Declines ◽  
Egyptian Vulture ◽  
Breeding Grounds ◽  
Conservation Actions ◽  
Causes Of Mortality ◽  
Yugoslav Republic

SummaryThe Egyptian Vulture has been classified as ‘Endangered’ due to a rapid population decline in India and long term declines in Europe and Africa. Although the species has been reported to be declining in Eastern Europe, no quantitative assessment of the magnitude or the causes for population declines are available. We used monitoring data from the Balkan Peninsula to estimate changes in population size and extent of occurrence of Egyptian Vultures between 1980 and 2013. We quantified population trends in three countries (Bulgaria, Greece and the former Yugoslav Republic [FYR] of Macedonia) to assess whether population declines are similar within the Balkan range states. We found a rapid and consistent decline of the Egyptian Vulture population that was largely similar among the three countries (λ = 0.940 in FYR of Macedonia, 0.951 in Bulgaria, 0.920 in Greece). As a consequence of population declines, the breeding range of Egyptian Vultures has contracted and the population in the Balkan Peninsula has fragmented into six subpopulations separated by more than 80 km. Population declines may be driven by factors such as poisoning, electrocution, direct persecution and changes in food availability which operate at large spatial scales and affect birds both on breeding grounds as well as during migration and wintering. Because the relative importance of threats to the survival of Egyptian Vultures are poorly understood, there is a critical need for research into causes of mortality and potential conservation actions that may halt and reverse population declines.

scholarly journals Testing for Geographic Variation in Survival of Spectacled Eider (Somateria fischeri) Populations in Chukotka, Russia and the Yukon-Kuskokwim Delta, Alaska

ARCTIC ◽  
2017 ◽  
Vol 70 (3) ◽  
pp. 287 ◽  
Author(s):  
Diana V. Solovyeva ◽  
Vera Yu. Kokhanova ◽  
Melissa Gabrielson ◽  
Katherine S. Christie
Keyword(s):  
Linear Trend ◽  
Survival Rates ◽  
Annual Survival ◽  
Breeding Populations ◽  
Island Sample ◽  
Size Constraints ◽  
Breeding Grounds ◽  
Female Survival ◽  
Likelihood Approach ◽  
Over Time

Information on variation in survival among geographically distinct breeding populations can produce valuable insights about the population dynamics of a species. The Yukon-Kuskokwim Delta sub-population of Spectacled Eiders in Alaska decreased precipitously between the 1950s and 1990s. Causes for this decline are unknown but may be attributed to low female survival due to predation and lead exposure on the breeding grounds. From 2014 to 2015, we compared annual survival probabilities of Spectacled Eiders on Kigigak Island in the Yukon-Kuskokwim Delta, Alaska, and Ayopechan Island in the Chaun Delta, Chukotka, where similar field protocols were implemented. A Cormack-Jolly-Seber maximum likelihood approach was used to estimate apparent survival (φ) and recapture probability (p) from mark-resight data. We tested a) whether Russian and Alaskan sub-populations differed in their survival rates, b) whether survival varied annually, and c) whether survival followed an increasing or decreasing trend over time at either site. We found no evidence for differing survival between the two breeding areas when mean survival across years was compared, and we did not find strong evidence for a linear trend in survival over time at either site. Furthermore, our data supported models with annually varying survival at Kigigak Island and constant survival at Ayopechan Island. Sample size constraints precluded estimates of annual survival at Ayopechan Island. Our finding of no difference in mean survival between sites lends support to the idea that survival may be a function of conditions on the wintering grounds.

scholarly journals Effects of Water Conditions on Clutch Size, Egg Volume, and Hatchling Mass of Mallards and Gadwalls in the Prairie Pothole Region

The Condor ◽  
2000 ◽  
Vol 102 (4) ◽  
pp. 936-940 ◽  
Author(s):  
Pamela J. Pietz ◽  
Gary L. Krapu ◽  
Deborah A. Buhl ◽  
David A. Brandt
Keyword(s):  
North Dakota ◽  
Clutch Size ◽  
Prairie Pothole Region ◽  
Prairie Pothole ◽  
Egg Volume ◽  
Water Conditions ◽  
Breeding Grounds ◽  
Using Data ◽  
The Relationship ◽  
Basin Area

AbstractWe examined the relationship between local water conditions (measured as the percent of total area of basins covered by water) and clutch size, egg volume, and hatchling mass of Mallards (Anas platyrhynchos) and Gadwalls (A. strepera) on four study sites in the Prairie Pothole Region of North Dakota and Minnesota, 1988–1994. We also examined the relationship between pond density and clutch size of Mallards and Gadwalls, using data collected at another North Dakota site, 1966–1981. For Mallards, we found no relationships to be significant. For Gadwalls, clutch size increased with percent basin area wet and pond density; hatchling mass marginally increased with percent basin area wet. These species differences may reflect, in part, that Mallards acquire lipid reserves used to produce early clutches before they reach the breeding grounds, whereas Gadwalls acquire lipid reserves locally; thus Gadwall clutches are more likely to be influenced by local food resources.

scholarly journals ESTIMATION OF CARCASS FAT AND PROTEIN IN NORTHERN PINTAILS (ANAS ACUTA) DURING SPRING MIGRATION

2003 ◽  
Vol 39 (3) ◽  
pp. 620-626 ◽  
Author(s):  
Pascale Dombrowski ◽  
Jean-Claude Bourgeois ◽  
Richard Couture ◽  
Christian Linard
Keyword(s):  
Spring Migration ◽  
Anas Acuta ◽  
Northern Pintails

Migration distance is a fundamental axis of the slow-fast continuum of life history in boreal birds

The Auk ◽  
2021 ◽  
Author(s):  
Benjamin M Winger ◽  
Teresa M Pegan
Keyword(s):  
Life History ◽  
Survival Rates ◽  
Reproductive Investment ◽  
Seasonal Migration ◽  
Adult Survival ◽  
Vital Rates ◽  
Long Distance ◽  
Migration Distance ◽  
Breeding Grounds ◽  
Survival And Reproduction

Abstract Seasonal migration is intrinsically connected to the balance of survival and reproduction, but whether migratory behavior influences species’ position on the slow-fast continuum of life history is poorly understood. We found that boreal-breeding birds that migrate long distances exhibit higher annual adult survival and lower annual reproductive investment relative to co-distributed boreal species that migrate shorter distances to winter closer to their breeding grounds. Our study uses “vital rates” data on reproductive output and survivorship compiled from the literature for a species assemblage of 45 species of mostly passerine birds. These species breed sympatrically in North American boreal forests but migrate to a diversity of environments for the northern winter. After controlling for body size and phylogeny, migration distance and apparent annual adult survival are positively related across species. Both migration distance and survival are positively correlated with wintering in environments that are warmer, wetter, and greener. At the same time, longer migrations are associated with reduced time spent on the breeding grounds, lower clutch sizes, and lower fecundity (clutch size × maximum number of broods per year). Although seasonal migration is often associated with high mortality, our results suggest that long-distance migration imposes selection pressures that both confer and demand high adult survival rates. That is, owing to the reproductive cost of long-distance migration, this strategy can only persist if balanced by high adult survival. Our study supports the idea that migration evolves to promote survival of species breeding in seasonal environments. In boreal birds, the evolution of the longest migrations yields the highest survival, but at an inherent cost to annual fecundity. Our results therefore reveal migratory distance as a fundamental axis of the slow-fast continuum that predicts, and is inextricable from, the balance of survival and reproduction.

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