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.

Comparative hunting abilities of polar bear cubs of different ages

1978 ◽  
Vol 56 (8) ◽  
pp. 1768-1772 ◽  
Author(s):  
Ian Stirling ◽  
Paul B. Latour
Keyword(s):  
Polar Bear ◽  
Canadian Arctic ◽  
Ursus Maritimus ◽  
Adult Males ◽  
Age Classes ◽  
Adult Age ◽  
Probability Of Survival ◽  
Age Class ◽  
Management Concept ◽  
Kill Rate

In most areas of the Canadian Arctic polar bear (Ursus maritimus) cubs apparently remain with their mothers until they are 2.5 years of age. The degree to which cubs of each age-class participate in the hunting of seals while with their mothers is examined in this paper in order to evaluate the degree to which they might be capable of independent hunting, should they be orphaned prior to the completion of the normal weaning period. Cubs of all age-classes did almost no hunting during the spring. The proportions of time spent hunting by yearling and 2-year-old cubs, and the durations of their lying 'still hunts' were not significantly different from each other but they were significantly shorter than their mothers' and than adult males' during the summer. However, the frequency of the lying 'still hunts' of 2-year-old cubs was double that of yearling cubs and the kill rate of 2-year-old cubs was comparable with that of adult age-classes, despite the fact they hunted for a significantly lesser proportion of their time. These results suggest that cubs which remain with their mothers until they are weaned have a higher probability of survival than those that do not and this interpretation lends support lo the management concept of total protection of family groups and the harvesting of independent bears only.

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.

The Biology of the Northern Brown Bandicoot, Isoodon-Macrourus (Marsupialia, Peramelidae) at Mitchell Plateau, Western-Australia

1989 ◽  
Vol 37 (6) ◽  
pp. 627 ◽  
Author(s):  
C Kemper ◽  
DJ Kitchener ◽  
WF Humphreys ◽  
RA How ◽  
LH Schmitt ◽  
...  
Keyword(s):  
Blood Cells ◽  
White Blood Cells ◽  
Breeding Population ◽  
Dry Season ◽  
Physiological Parameters ◽  
Adult Males ◽  
Wet Season ◽  
Young Females ◽  
Adult Females ◽  
Overall Ratio

Breeding, population dynamics and seasonal changes in physical and physiological parameters were examined in Isoodon macrourus at the Mitchell Plateau between September 1981 and November 1982. Females gave birth to litters of 2.5 � 1.0 (16) young between September and April. They produced up to three litters in a breeding season with an average interval between successive litters of 89.5 (51-108) days. Adult testosterone levels and scrota1 size began to increase in July and peaked in September 1982. The overall ratio of adult males to adult females was 1:0.54; it was 1:0.80 for pouch young. Females were more frequently trapped on sequential trips than were males. Density on the grids increased towards the end of the dry season (July and September 1982)-mostly as a result of increased numbers of females. Adult males and females moving onto the grids during the dry season tended to select different habitats. Adult males moved significantly more in the wet season (September 1981, January and April) than they did in the dry season (July and September 1982); they also moved significantly more than adult females in the wet season. Seasonal variations were recorded for most physical and physiological parameters. During the wet period from September 1981 to January 1982, body weight, haemoglobin, haematocrit and total plasma albumin declined, while total white blood cells and proportion of lymphocytes to granular leucocytes rose. This indicated that this period was one of change in condition for this species. Compared to adult females, adult males were larger and heavier, had higher values of haematocrit and lymphocytes, and lower values of granular leucocytes, free steroids, CBGBd and albumin bound corticosteroid. There was considerable between-year variability in condition of individuals and both sexes differed significantly in September 1981 and 1982 in their weight, haematocrit, total white blood cells, granular leucocytes, MCBC and testosterone. Individuals at disparate localities at the Mitchell Plateau showed similar seasonal physiological and physical responses, except for one grid where they were heavier.

scholarly journals Body Condition and Survival of Vagrant Long-billed Murrelets, Brachyramphus perdix, in North America

2012 ◽  
Vol 126 (1) ◽  
pp. 6 ◽  
Author(s):  
Spencer G. Sealy ◽  
Harry R. Carter
Keyword(s):  
North America ◽  
Body Condition ◽  
West Coast ◽  
Atlantic Coast ◽  
Breeding Population ◽  
Adult Males ◽  
Long Distance ◽  
The West ◽  
Stopover Sites ◽  
America South

From 1979 through 2009, 81 records of long-distance vagrancy in the Long-billed Murrelet (Brachyramphus perdix) in North America south of Alaska were examined to assess body condition and survival after first observation. Sixty-one records were of live birds, of which 38 (62.3%) were discovered at sea along the west coast of North America, 18 (29.5%) were encountered inland, and 5 (8.2%) were encountered along the Atlantic coast. Fifteen of the 20 individuals salvaged (19 adults, 1 juvenile) were discovered on lake shores (75.0%) and the other 5 (25.0%) on marine coasts; 85.0% were dead when initially found (15 dead, 2 shot), and 3 (15.0%) were moribund (2 died within one day, 1 later released). Of 10 sexed individuals, 5 were adult males, 4 were adult females, and 1 was a juvenile female. Eight of 10 murrelets observed foraging were diving on lakes, but 2 others surfaced with fish; two species of common freshwater fish were removed from stomachs of 2 birds shot by hunters. Most birds (72.1%, n = 61) disappeared after one observation, which suggests survival and moving on; one bird stayed at the same location for at least 25 days before disappearing. Dead or dying Long-billed Murrelets found on shorelines of fresh water may have been too emaciated to regain lost mass after arrival—they weighed less than those shot, presumably because they were not able to locate prey or too weak to capture it. Survival for weeks or longer on freshwater stopover sites better explains how Long-billed Murrelets move across North America, with some reaching the Atlantic Ocean. Long-surviving vagrants may establish a new breeding population of Long-billed Murrelet on the west coast of North America.

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.

Juvenile survival and recruitment in a population of Weddell seals (Leptonychotes weddellii) in McMurdo Sound, Antarctica

1987 ◽  
Vol 65 (12) ◽  
pp. 2993-2997 ◽  
Author(s):  
J. Ward Testa
Keyword(s):  
Census Data ◽  
Survival Rates ◽  
Breeding Population ◽  
Weddell Seal ◽  
Adult Survival ◽  
Juvenile Survival ◽  
Apparent Survival ◽  
Mcmurdo Sound ◽  
Juvenile Dispersal ◽  
Weddell Seals

Survival and recruitment of Weddell seal pups were studied in eastern McMurdo Sound, Antarctica. Pups were marked and their apparent survival estimated by mark–recapture methods. The resulting estimates were used together with published estimates of adult survival, yearly sighting probabilities, and direct counts of pup production to simulate the dynamics of the population and evaluate the assumption that it is closed to immigration. Estimates derived from census data in 1982 and 1983 were over five times larger than those simulated. This discrepancy was due to the extremely low juvenile survival rates calculated from marked seals. Since few animals born in Erebus Bay return to breed, the large adult breeding population must be the result of substantial immigration, indicating an important role for juvenile dispersal in the population dynamics of Weddell seals.

Exposure of Spectacled Eiders and other diving ducks to lead in western Alaska

1997 ◽  
Vol 75 (3) ◽  
pp. 439-443 ◽  
Author(s):  
Paul L. Flint ◽  
Margaret R. Petersen ◽  
J. Barry Grand
Keyword(s):  
Blood Lead ◽  
Breeding Population ◽  
Atomic Absorption Spectrophotometry ◽  
Adult Males ◽  
Long Term Effects ◽  
Brood Rearing ◽  
Diving Ducks ◽  
Adult Females ◽  
Lead Levels

Lead poisoning, resulting from ingestion of spent shot, has been identified as a cause of mortality in Spectacled Eiders (Somateria fischeri) on the Yukon–Kuskokwim Delta, Alaska. We examined lead-exposure rates of adult and juvenile Spectacled Eiders and other diving ducks, using atomic absorption spectrophotometry of blood samples. Additionally, we X-rayed birds in the field to identify ingested shot. We detected shot in the gizzards of 11.6% of Spectacled Eiders X-rayed. During the period from arrival through incubation, 13.0% of adult females and 6.6% of adult males had elevated blood lead levels when captured. During the brood-rearing period, 35.8% of adult females and 12.2% of ducklings were exposed to lead when captured. There was an increase in the probability of exposure of adult females with date sampled. We predict that 50% of the successfully breeding hens were likely exposed to lead, and 25–37% of the Spectacled Eider breeding population was exposed to lead. The long-term effects of sublethal doses on Spectacled Eiders are unknown; however, exposure of nesting females and young birds to lead may result in reduced over-winter survival and (or) reduced fecundity.

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.

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