Factors Affecting Winter Distribution and Migration Distance of Wood Ducks from Southern Breeding Populations

Predictions of the time-allocation hypothesis were tested with several a posteriori analyses of banding data for the mallard (Anas platyrhynchos). The time-allocation hypothesis states that the critical difference between resident and migrant birds is their allocation of time to reproduction on the breeding grounds and survival on the nonbreeding grounds. Residents have higher reproduction and migrants have higher survival. Survival and recovery rates were estimated by standard band-recovery methods for banding reference areas in the central United States and central Canada. A production-rate index was computed for each reference area with data from the U.S. Fish and Wildlife Service May Breeding Population Survey and July Production Survey. An analysis of covariance was used to test for the effects of migration distance and time period (decade) on survival, recovery, and production rates. Differences in migration chronology were tested by comparing direct-recovery distributions for different populations during the fall migration. Differences in winter locations were tested by comparing distributions of direct recoveries reported during December and January. A strong positive relationship was found between survival rate and migration distance for 3 of the 4 age and sex classes. A weak negative relationship was found between recovery rate and migration distance. No relationship was found between production rate and migration distance. During the fall migration, birds from the northern breeding populations were located north of birds from the southern breeding populations. No pattern could be found in the relative locations of breeding and wintering areas. Although our finding that survival rate increased with migration distance was consistent with the time-allocation hypothesis, our results on migration chronology and location of wintering areas were not consistent with the mechanism underlying the time-allocation hypothesis. Neither this analysis nor other recent studies of life-history characteristics of migratory and resident birds supported the time-allocation hypothesis.

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Males migrate farther than females in a differential migrant: an examination of the fasting endurance hypothesis

Royal Society Open Science ◽

10.1098/rsos.140346 ◽

2014 ◽

Vol 1 (4) ◽

pp. 140346 ◽

Cited By ~ 13

Author(s):

Elizabeth A. Gow ◽

Karen L. Wiebe

Keyword(s):

Parental Care ◽

Intraspecific Variation ◽

Experimental Studies ◽

Light Level ◽

Migration Distance ◽

Individual Fitness ◽

The North ◽

Breeding Populations ◽

Migration Strategies ◽

And Migration

Patterns of migration including connectivity between breeding and non-breeding populations and intraspecific variation in the distance travelled are important to study because they can affect individual fitness and population dynamics. Using data from 182 band recoveries across North America and 17 light-level geolocators, we examined the migration patterns of the northern flicker ( Colaptes auratus ), a migratory woodpecker. This species is unusual among birds because males invest more in parental care than females. Breeding latitude was positively correlated to migration distance because populations in the north appeared to travel farther distances than southern populations to find wintering locations with little snow cover. Connectivity was strong for populations west and east of the Continental Divide. Contrary to the three main hypotheses for intraspecific variation in migration distance, females wintered, on average, farther north than males, although there was overlap throughout their non-breeding range. This pattern contradicts those of other species found to date and is most consistent with the fasting endurance hypothesis if investment in parental care depletes the energy reserves of male flickers more than females. We thus propose a new factor, parental effort, which may influence optimal wintering areas and migration strategies within birds, and encourage future experimental studies to test the relationship between parental care roles and migration strategies of the sexes.

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Winter distribution and migration of the sound scattering layers, zooplankton and micronekton in Masfjorden, western Norway

Marine Ecology Progress Series ◽

10.3354/meps095035 ◽

1993 ◽

Vol 95 ◽

pp. 35-50 ◽

Cited By ~ 1

Author(s):

BM Balino ◽

DL Aksnes

Keyword(s):

Sound Scattering ◽

Winter Distribution ◽

Western Norway ◽

And Migration

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Environmental factors affecting the wintering raptor community in Armenia, Southern Caucasus

Community Ecology ◽

10.1007/s42974-021-00038-7 ◽

2021 ◽

Author(s):

Gianpasquale Chiatante ◽

Michele Panuccio

Keyword(s):

General Pattern ◽

Abundant Species ◽

Theoretic Approach ◽

Factors Affecting ◽

Milvus Migrans ◽

Gyps Fulvus ◽

Black Kite ◽

Southern Caucasus ◽

And Migration ◽

Information Theoretic Approach

AbstractThe species–habitat relationships can change during the year because of the seasonality of resources. Therefore, the investigation of habitat use by animals in each season plays a fundamental role in their conservation. The main aim of this research was to investigate the raptor community that spends the winter in Armenia, southern Caucasus, and to explore its relationship with environmental features, such as land use and topography. During January 2012, we collected data by carrying out 15 roadside counts along which we calculated three community parameters: the relative abundance, the species richness, and the species diversity. Then, we carried out a multiple linear regression with the Information-Theoretic Approach, to explain the relationship between the parameters and environmental variables. Besides, we computed a Canonical Correspondence Analysis (CCA) between the species and the environment around their observations. As a general pattern, the community was associated with permanent crops, maybe because of their heterogeneity, which in turn allows them to support higher densities of prey during the winter. The most abundant species was the Black Kite (Milvus migrans), followed by the Common Kestrel (Falco tinnunculus) and the Griffon Vulture (Gyps fulvus). To our knowledge, this is one of the first studies investigating the wintering raptor community in the Caucasus, with raptors generally studied in this area during the breeding season and migration.

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