Sex and age differences in distribution, abundance, and habitat preferences of wintering Harlequin Ducks: implications for conservation and estimating recruitment rates

2003 ◽  
Vol 81 (3) ◽  
pp. 492-503 ◽  
Author(s):  
Michael S Rodway ◽  
Heidi M Regehr ◽  
Fred Cooke
Keyword(s):  
Habitat Preferences ◽  
Adult Survival ◽  
Survey Method ◽  
Adult Males ◽  
Intertidal Habitat ◽  
Age Classes ◽  
Specific Distribution ◽  
Age Ratio ◽  
Harlequin Ducks ◽  
Sex And Age Differences

We determined the sex- and age-specific distribution, abundance, and habitat preferences of wintering Harlequin Ducks (Histrionicus histrionicus) and evaluated potential biases in measuring ratios of immature males to adult males to estimate recruitment rates. A comparison of the occurrence of birds with habitat availability at the 1-km scale indicated a preference for wide intertidal habitat with cobble–gravel or bedrock–boulder substrate, small offshore islets and shoreline with attached or nearby reefs and islets, areas without streams, and areas with a greater historical abundance of herring spawn. Where the substrate was bedrock–boulder, birds preferred areas with tidal rapids. Densities of birds were highest along linear and complex shorelines with reefs or islets where intertidal habitat was >100 m wide and substrate was cobble–gravel or bedrock–boulder. Patterns of habitat use among sex and age classes were the same at the 1-km scale but differed at smaller scales, with adult and immature males occurring farther offshore than females. Age ratios varied among areas and were biased by survey method and misidentification of distant birds. Correcting for detected biases gave an estimated male age ratio of 9.8%. Calculated estimates of female recruitment suggest a declining population, but it is necessary to incorporate emigration in estimates of adult survival before demographic trends can be confidently inferred.

Habitat preferences of polar bears in the western Canadian Arctic in late winter and spring

Polar Record ◽  
1993 ◽  
Vol 29 (168) ◽  
pp. 13-24 ◽  
Author(s):  
Ian Stirling ◽  
Dennis Andriashek ◽  
Wendy Calvert
Keyword(s):  
Sea Ice ◽  
Habitat Preferences ◽  
Canadian Arctic ◽  
Late Winter ◽  
Polar Bears ◽  
Adult Males ◽  
Age Classes ◽  
Habitat Types ◽  
Adult Females ◽  
Fast Ice

ABSTRACTBetween late March and May, from 1971 through 1979, we surveyed 74,332 km2 of sea-ice habitatin the eastern Beaufort Sea and Amundsen Gulf in the western Canadian Arctic. We defined seven sea-ice habitat types and recorded sightings of polar bears and their tracks in each to determine their habitat preferences. 791 bears (including cubs) and 6454 sets of tracks were recorded. 42.3%, 39.7%, and 15.6% of the bears were seen on floe-edge, moving ice, and drifted fast-ice habitats, respectively. Significant differences in habitat preferences were shown by bears of different sexes and age classes. Adult females accompanied by cubs of the year were the only group that showed a strong preference for fast ice with drifts, probably because they could feed adequately there while avoiding adult males that might prey upon their cubs. The highest densities of seals are found in floe-edge and moving ice habitats and this likely explains the predominance of bears there. Lone adult females and females with two-year-old cubs, adult males, and subadult males were found two and one-half to four times more frequently than predicted in floe-edge habitat. Since there are no data to suggest seals are more abundant along the floe edge than in moving ice habitat, the preference of these groups of adult polar bears for the floe edge in spring may be related to reproductive behavior.

Design of experimental food patches to measure foraging intensity for octopus: a case study with the giant Pacific octopus Enteroctopus dofleini

2020 ◽  
Author(s):  
Stephanie Chancellor ◽  
David Scheel ◽  
Joel S Brown
Keyword(s):  
Predation Risk ◽  
Foraging Behaviour ◽  
Habitat Preferences ◽  
High Tide ◽  
Intertidal Habitat ◽  
Camera System ◽  
Subtidal Habitat ◽  
Enteroctopus Dofleini ◽  
Nontarget Species

ABSTRACT In a study of the foraging behaviour of the giant Pacific octopus Enteroctopus dofleini, we designed two types of experimental food patches to measure habitat preferences and perceptions of predation risk. The first patch successfully measured giving-up densities (GUDs), confirmed by octopus prey presence and higher foraging at sites with historically greater octopus presence. However, nontarget foragers also foraged on these experimental food patches. Our second floating patch design successfully excluded nontarget species from subtidal patches, and from intertidal patches at high tide, but allowed for foraging by E. dofleini. The second design successfully measured GUDs and suggested that octopus preferred foraging in a subtidal habitat compared to an intertidal habitat. We ascribe the higher GUD in the intertidal habitat to its higher predation risk relative to the subtidal habitat. The second patch design seems well suited for E. dofleini and, in conjunction with a camera system, could be used to provide behavioural indicators of the octopus's abundance, perceptions of habitat quality and predation risk.

scholarly journals Social affiliation matters: both same-sex and opposite-sex relationships predict survival in wild female baboons

2014 ◽  
Vol 281 (1793) ◽  
pp. 20141261 ◽  
Author(s):  
Elizabeth A. Archie ◽  
Jenny Tung ◽  
Michael Clark ◽  
Jeanne Altmann ◽  
Susan C. Alberts
Keyword(s):  
Animal Studies ◽  
Social Connectedness ◽  
Dominance Rank ◽  
Limited Resource ◽  
Adult Survival ◽  
Adult Males ◽  
Same Sex ◽  
Wild Female ◽  
Opposite Sex ◽  
Socially Isolated

Social integration and support can have profound effects on human survival. The extent of this phenomenon in non-human animals is largely unknown, but such knowledge is important to understanding the evolution of both lifespan and sociality. Here, we report evidence that levels of affiliative social behaviour (i.e. ‘social connectedness’) with both same-sex and opposite-sex conspecifics predict adult survival in wild female baboons. In the Amboseli ecosystem in Kenya, adult female baboons that were socially connected to either adult males or adult females lived longer than females who were socially isolated from both sexes—females with strong connectedness to individuals of both sexes lived the longest. Female social connectedness to males was predicted by high dominance rank, indicating that males are a limited resource for females, and females compete for access to male social partners. To date, only a handful of animal studies have found that social relationships may affect survival. This study extends those findings by examining relationships to both sexes in by far the largest dataset yet examined for any animal. Our results support the idea that social effects on survival are evolutionarily conserved in social mammals.

Observations on Activity Patterns, Population and Den Characteristics of The Water Rat Hydromys chrysogaster Along Badger Creek, Victoria.

1995 ◽  
Vol 18 (1) ◽  
pp. 71
Author(s):  
J.L. Gardner ◽  
M. Serena
Keyword(s):  
Population Density ◽  
Activity Patterns ◽  
Home Ranges ◽  
Adult Males ◽  
Fish Farms ◽  
Age Classes ◽  
Irrigation Channels ◽  
In Captivity ◽  
In The Wild ◽  
Hydromys Chrysogaster

The Water Rat Hydromys chrysogaster is Australia's largest amphibious rodent, occupying freshwater rivers, lakes, and coastal and estuarine habitats throughout the continent (Watts and Aslin 1981). Little is known of the species' social organisation or use of space in the wild although Harris (1978) suggested that adults might be intrasexually aggressive. The home ranges of all sex and age classes overlap to some extent but home ranges of adults of the same sex appear to overlap less (Harris 1978). Adult males occupy the largest home ranges which overlap those of one or more females. In captivity individuals kept in groups form hierarchies in which only the dominant females usually breed successfully (Olsen 1982). Fighting occurs primarily among males, with the highest incidence of injuries observed at the beginning of the main September-March breeding season (Olsen 1980, 1982). The results of trapping studies indicate that population density may vary considerably, with the greatest numbers of animals typically occupying man-modified habitats such as irrigation channels or fish farms (McNally 1960, Watts and Aslin 1981, Smales 1984). Aggressive behaviour appears to be related to pelage colour (phenotype) and population density; the higher the density the greater the number of injured individuals (Olsen 1980).

Aggregating Behavior of Ovigerous Female Red King Crab, Paralithodes camtschaticus, in Auke Bay, Alaska

1993 ◽  
Vol 50 (4) ◽  
pp. 750-758 ◽  
Author(s):  
Robert P. Stone ◽  
Charles E. O'Clair ◽  
Thomas C. Shirley
Keyword(s):  
Shallow Water ◽  
Nearest Neighbor ◽  
Ovigerous Female ◽  
Early Spring ◽  
Late Winter ◽  
Red King Crab ◽  
Paralithodes Camtschaticus ◽  
Adult Males ◽  
Age Classes ◽  
King Crab

Ovigerous female red king crab, Paralithodes camtschaticus, monitored with ultrasonic biotelemetry, displayed distinct seasonal shifts in habitat use and bathymetric distribution. Crab occupied deep water between June and mid-November, relatively shallow water between mid-November and early March, and returned to deeper water prior to molting and mating in spring. Females were nonrandomly distributed within both depth ranges but seasonally changed their behavior and degree of association with conspecifics. Tagged crab were more aggregated (lower mean nearest neighbor distances) in winter than in summer and fall (F-test, P < 0.01). Winter SCUBA observations supported these results; females of mixed age-classes formed dense aggregations in shallow water, and crab exhibited "podding" behavior similar to that reported for younger age-classes. Adult males were associated with aggregations during late winter and early spring. Observations from the manned submersible Delta indicated that females were nonrandomly distributed in the deepwater habitat as well and probably formed loosely knit feeding aggregations there. Seasonal changes in aggregation densities and benthic areas used were the same during the two consecutive years of this study.

Effects of adults on the demography of fox squirrels (Sciurus niger)

1985 ◽  
Vol 63 (4) ◽  
pp. 861-867 ◽  
Author(s):  
Lonnie P. Hansen ◽  
Charles M. Nixon
Keyword(s):  
Home Range Size ◽  
Adult Males ◽  
Sciurus Niger ◽  
Age Classes ◽  
Control Grid ◽  
Local Populations ◽  
Adult Females ◽  
Resource Limited ◽  
Fox Squirrels ◽  
Reproductive Rates

As a test of the hypothesis that adult fox squirrels (Sciurus niger) regulate the number of immature and adult squirrels entering a population, each fall from 1979 to 1981 adult males were removed from two grids (male-removal grids, MRGs), adult females from two grids (female-removal grids, FRGs), all adults from one grid (adult-removal grid, ARG), and one grid was maintained as a control (control grid, CG). The number of previously uncaptured juveniles and subadults (both sexes) and yearling–adult females was greater on FRGs than on the CG and MRGs, especially during the fall. The number of new adult males captured during the fall was higher where adult males had been removed. During spring, reproductive rates (percent lactating) were higher on grids from which females had been removed (FRGs and the ARG), but this was not so during fall. Length of residency was shorter for juvenile–subadult and adult fox squirrels and longer for yearling females where adult females had been removed. Movement patterns in response to removal of adults suggested resident adult females influenced home range size of all sex classes and age-classes. We conclude that the presence of adult females is important in limiting recruitment in local populations of fox squirrels and that this strategy likely evolved in response to resource-limited environments.

Moulting matters: the importance of understanding moulting cycles in bats when using fur for endogenous marker analysis

2013 ◽  
Vol 91 (8) ◽  
pp. 533-544 ◽  
Author(s):  
E.E. Fraser ◽  
F.J. Longstaffe ◽  
M.B. Fenton
Keyword(s):  
Skin Pigmentation ◽  
Data Interpretation ◽  
Tropical Species ◽  
Tissue Formation ◽  
Adult Males ◽  
Age Classes ◽  
Knowledge Gaps ◽  
Detailed Understanding ◽  
Sampling Protocols ◽  
Colour Changes

Endogenous markers are a valuable indicator of individual animal ecology, but data interpretation requires a detailed understanding of the timing of tissue formation. Fur is commonly used in bat research using endogenous markers, but the moulting cycles of most bat species are not well documented. In this review, we (i) describe methods of investigating bat moulting; (ii) summarize the current literature on bat moulting cycles, highlighting broad trends; (iii) discuss knowledge gaps; and (iv) make recommendations for optimal fur sampling protocols. Three characteristics may indicate moulting in bats: changing skin pigmentation; visible fur growth and colour changes; and endogenous markers. Most studies reported new fur growth once annually during summer–fall, although there were exceptions. The timing of new fur growth varies among species, sexes, and age classes. Individuals commonly experience asynchronous new fur growth, with dorsal fur growth occurring before ventral. Specific moult progressions vary among species. Knowledge gaps include moulting cycles in tropical species and in subadult and yearling bats; migration during new fur growth; and the timing of fur growth compared with shedding. We recommend that fur samples taken dorsally from adult males are the most likely to be representative of the bat’s site of summer residency.

scholarly journals Poor horse traders: large mammals trade survival for reproduction during the process of feralization

2009 ◽  
Vol 276 (1663) ◽  
pp. 1911-1919 ◽  
Author(s):  
Sophie Grange ◽  
Patrick Duncan ◽  
Jean-Michel Gaillard
Keyword(s):  
Population Growth ◽  
Reproductive Performance ◽  
High Density ◽  
Adult Survival ◽  
Demographic Parameters ◽  
Adult Males ◽  
High Fecundity ◽  
Population Growth Rates ◽  
Feral Animals ◽  
Feral Ungulates

We investigated density dependence on the demographic parameters of a population of Camargue horses ( Equus caballus ), individually monitored and unmanaged for eight years. We also analysed the contributions of individual demographic parameters to changes in the population growth rates. The decrease in resources caused a loss of body condition. Adult male survival was not affected, but the survival of foals and adult females decreased with increasing density. Prime-aged females maintained high reproductive performance at high density, and their survival decreased. The higher survival of adult males compared with females at high density presumably results from higher investment in reproduction by mares. The high fecundity in prime-aged females, even when at high density, may result from artificial selection for high reproductive performance, which is known to have occurred in all the major domestic ungulates. Other studies suggest that feral ungulates including cattle and sheep, as these horses, respond differently from wild ungulates to increases in density, by trading adult survival for reproduction. As a consequence, populations of feral animals should oscillate more strongly than their wild counterparts, since they should be both more invasive (as they breed faster), and more sensitive to harsh environmental conditions (as the population growth rate of long-lived species is consistently more sensitive to a given proportional change in adult survival than to the same change in any other vital rate). If this principle proves to be general, it has important implications for management of populations of feral ungulates.

scholarly journals Temporal and spatial variation in age-specific survival rates of a long-lived mammal, the Hawaiian monk seal

2006 ◽  
Vol 274 (1608) ◽  
pp. 407-415 ◽  
Author(s):  
Jason D Baker ◽  
Paul M Thompson
Keyword(s):  
Survival Rates ◽  
Adult Survival ◽  
Age Classes ◽  
Temporal And Spatial Variation ◽  
Monachus Schauinslandi ◽  
Breeding Sites ◽  
Capture Recapture ◽  
Temporal And Spatial ◽  
Spatio Temporal ◽  
Monk Seals

Estimates of variability in pinniped survival rates are generally based on observations at single sites, so it is not certain whether observed rates represent the whole population. Here, we provide a comprehensive analysis of spatio-temporal variation in age-specific survival rates for endangered Hawaiian monk seals ( Monachus schauinslandi ) based on capture–recapture analyses of more than 85% of the pups weaned in this population over the last two decades. Uniquely, these data have been collected from six subpopulations, encompassing all major breeding sites across its 1800 km long core range. Analyses of individual subpopulations revealed similar patterns in age-specific survival, characterized by the relatively low survival rates from weaning to 2 years of age, intermediate rates to 4 years of age, and then by relatively high ‘mature’ survival rates until 17 years of age, after which a senescent decline was observed. Juvenile, subadult and adult survival rates all varied significantly over time. Trends in survival among subpopulations were coherent with their relative geographical positions, suggesting regional structuring and connectedness within the archipelago. Survival rates for different age classes tended to be positively correlated, suggesting that similar factors may influence the survival for seals of all ages.

Age-Specific Survival of Tundra Swans on the Lower Alaska Peninsula

The Condor ◽  
2013 ◽  
Vol 115 (2) ◽  
pp. 280-289 ◽  
Author(s):  
Brandt W. Meixell ◽  
Mark S. Lindberg ◽  
Paul B. Conn ◽  
Christian P. Dau ◽  
John E. Sarvis ◽  
...  
Keyword(s):  
Breeding Population ◽  
Adult Males ◽  
Age Classes ◽  
Apparent Survival ◽  
Alaska Peninsula ◽  
Cygnus Columbianus ◽  
Probability Of Survival ◽  
Izembek National Wildlife Refuge ◽  
Post Hoc ◽  
Southern Extremity

Abstract. The population of Tundra Swans (Cygnus columbianus columbianus) breeding on the lower Alaska Peninsula represents the southern extremity of the species' range and is uniquely nonmigratory. We used data on recaptures, resightings, and recoveries of neck-collared Tundra Swans on the lower Alaska Peninsula to estimate collar loss, annual apparent survival, and other demographic parameters for the years 1978– 1989. Annual collar loss was greater for adult males fitted with either the thinner collar type (0.34) or the thicker collar type (0.15) than for other age/sex classes (thinner: 0.10, thicker: 0.04). The apparent mean probability of survival of adults (0.61) was higher than that of immatures (0.41) and for both age classes varied considerably by year (adult range: 0.44–0.95, immature range: 0.25–0.90). To assess effects of permanent emigration by age and breeding class, we analyzed post hoc the encounter histories of swans known to breed in our study area. The apparent mean survival of known breeders (0.65) was generally higher than that of the entire marked sample but still varied considerably by year (range 0.26–1.00) and indicated that permanent emigration of breeding swans was likely. We suggest that reductions in apparent survival probability were influenced primarily by high and variable rates of permanent emigration and that immigration by swans from elsewhere may be important in sustaining a breeding population at and near Izembek National Wildlife Refuge.

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