Primary molt of blue grouse (Dendragapus obscurus) and its relation to reproductive activity and migration

1977 ◽  
Vol 55 (11) ◽  
pp. 1782-1787
Author(s):  
Fred C. Zwickel ◽  
Jane A. Dake
Keyword(s):  
Rank Order ◽  
Reproductive Activity ◽  
Adult Males ◽  
Age Classes ◽  
East Central ◽  
Dendragapus Obscurus ◽  
Close Relationship ◽  
And Migration ◽  
Late Starters ◽  
Reproductive Activities

A total of 906 blue grouse (Dendragapus obscurus fuliginosus) were examined for primary molt from 1969 to 1976 on east-central Vancouver Island. First birds to molt were yearling males, followed by adult males, lone (broodless) females, and brood females, in that order. General reproductive activity of the different sex–age classes followed the same rank order (least to greatest). No brood hens molted until after their chicks were hatched, with adult females molting earliest, in relation to yearling females. The rates of molt of yearling males, adult males, and lone females were all linear but brood females, which began their molt latest, had an accelerated, curvilinear rate of molt. Our data most closely fit the hypothesis that molt is inhibited by reproductive activities. The close relationship between initiation of molt and reproductive activity agrees with data for most other species of north-temperate birds.There was no separation of molt and summer–autumn migration. The most likely explanation for an accelerated rate of molt in late starters is a preparation for winter.

POPULATION ATTRIBUTES OF BLUE GROUSE IN SOUTHWESTERN ALBERTA

1966 ◽  
Vol 44 (5) ◽  
pp. 799-814 ◽  
Author(s):  
D. A. Boag
Keyword(s):  
Mortality Rate ◽  
Adult Male ◽  
Age Distribution ◽  
Older Age ◽  
Home Ranges ◽  
Adult Males ◽  
Age Classes ◽  
Adult Females ◽  
Dendragapus Obscurus ◽  
Breeding Grounds

A population of blue grouse (Dendragapus obscurus) was studied over a 10-year period in southwestern Alberta. During this time a number of population attributes were documented. Density declined from a maximum of 47 adult males in 1955 to a minimum of 6 in 1964 on the 620-acre study area. Dispersion of adult male blue grouse on the breeding grounds was accomplished by establishing territories which averaged 1.5 ac. Adult females inhabited overlapping home ranges which averaged 43 ac in size. The age distribution among marked birds on the breeding grounds in May and June indicated 75% adult (2 years and older) and 25% subadult (1 year of age). Of the adults, approximately one-half were 2-year-olds with decreasing proportions in older age classes until none remained after they were 9 years old. Juveniles formed 40% of the fall population each year. The average hatch was 5.1 chicks per breeding female. Recruitment to the population has been inadequate to maintain numbers. Excessive mortality or dispersal rates must account for this. Minimum recorded loss of chicks during their first summer averaged 27%. Mortality rate of birds more than 1 year old averaged 56% per annum. Dispersal to other breeding ranges was recorded only in juvenile grouse.

DISEASE AS A CONTROL OF A POPULATION OF BLUE GROUSE, DENDRAGAPUS OBSCURUS FULIGINOSUS (RIDGWAY)

1955 ◽  
Vol 33 (3) ◽  
pp. 195-223 ◽  
Author(s):  
J. F. Bendell
Keyword(s):  
New Records ◽  
Population Control ◽  
Mortality Factor ◽  
First Year ◽  
Population Stability ◽  
Adult Males ◽  
Age Classes ◽  
Dendragapus Obscurus ◽  
Summer Range ◽  
First Year Of Life

A population of blue grouse was studied on its summer range at Quinsam Lake, Vancouver Island, to determine the factors of importance in population control. The population is stable with a density of 0.40 adult males and 0.78 yearling and adult females to the acre. A life table is constructed on the basis of a stable population, the death of 80% of the chicks in the first three months after hatch, and the death of 31% of the adults each year, as calculated from banding returns. The survivorship curve is negatively "J"-shaped. Mortality rates appear constant and independent of age after the first year of life. Space, weather, food, predators, and disease are considered as factors capable of population control. Six parasites are new records in this host. Two of the six, Plagiorhynchus formosus and Dispharynx nasuta occur commonly and almost exclusively in the chicks, where they cause extreme damage to the tissues of the gut. It is concluded that parasitism by these helminths is an important mortality factor in the chicks and a major cause of population stability—an equilibrium between death in the older age classes and replacement by surviving young.

Variations in courtship activity among male blue grouse: do some males breed more than others?

1993 ◽  
Vol 71 (6) ◽  
pp. 1079-1083
Author(s):  
David P. Hervieux ◽  
Fred C. Zwickel ◽  
Richard A. Lewis
Keyword(s):  
Late Summer ◽  
Reproductive Activity ◽  
Adult Males ◽  
Primary Feather ◽  
Adult Females ◽  
Dendragapus Obscurus ◽  
Courtship Activity ◽  
Wear Index

We developed a primary feather wear index (WI) for blue grouse (Dendragapus obscurus) to examine variations in courtship activity among males. Three percent of 276 yearling males, and less than 1% of 144 yearling and adult females examined throughout spring and summer showed evidence of such wear. Among 630 adult males, 48% exhibited "courtship wear." Mean courtship wear among males 2 years old and older increased steadily throughout the spring and summer, generally paralleling what would be predicted from cumulative reproductive activity. However, there was much variation among males, ranging from no wear to heavy wear, even by late summer. These data are consistent with earlier suggestions that breeding may be skewed among male blue grouse, as in lek-breeding tetraonines. Limited samples indicate that primary feather wear was not related to the age of males (more than 1 year old) or their occupancy of persistent or transient territorial sites.

Number of Shoes Tested During a Running Shoe Mass Perception Task May Not Influence Accuracy

2020 ◽  
Vol 127 (1-4) ◽  
pp. 23-29
Author(s):  
James G. Saxton ◽  
Joel G. Greenya ◽  
Christopher L. Kliethermes ◽  
David S. Senchina
Keyword(s):  
Young Adult ◽  
Experimental Design ◽  
Rank Order ◽  
Mass Accuracy ◽  
Testing Session ◽  
Adult Males ◽  
Order Task ◽  
Running Shoes ◽  
Design Factors ◽  
Analogue Scales

Commercially available running shoes differ in terms of their relative masses. It is unclear how well consumers may be able to judge mass differences from wearing alone, though previous studies suggest that perceptual outcomes may be influenced by experimental design factors such as the length of time worn. The purpose of this study was to investigate how the number of shoes used in a testing session impacts wearers' mass perceptual accuracy. Forty-eight young adult males ran for 5 min in 4 pairs of shoes (their own running shoes plus 3 unfamiliar pairs) before being asked whether an unfamiliar running shoe was heavier or lighter than their own, and to indicate perceptions of shoe heaviness (mass), comfort, stability, and temperature using visual analogue scales (VAS). A subset (n=18) was also asked to provide global rank orderings after wearing all 4 pairs of shoes. Participants were 67% accurate in the heavier/lighter task and 64% accurate in the global rank order task. Global rank order scores and VAS heaviness marks were significantly and positively correlated. Mass accuracy scores (n=48) were then compared to a previous study (n=25) performed by the same investigators using the same methods but with 6 pairs of shoes instead of 4. No difference in accuracy scores for either the heavier/lighter comparisons or global rank order scores between the study populations was found, suggesting that the number of test shoes may not influence mass perception accuracy.

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).

scholarly journals Actividad reproductiva y dieta de Hemidactylus frenatus (Sauria: Gekkonidae) en el norte de Colombia

2017 ◽  
Vol 57 (36) ◽  
pp. 459
Author(s):  
Jorge A. Díaz-Pérez ◽  
Alcides C. Sampedro-Marín ◽  
Martha P. Ramírez-Pinilla
Keyword(s):  
Diet Composition ◽  
Sampling Period ◽  
Reproductive Activity ◽  
Climatic Conditions ◽  
Relative Importance ◽  
Adult Males ◽  
Adult Females ◽  
Ecological Aspects ◽  
Environmental Availability ◽  
Hemidactylus Frenatus

Despite its success as an invasive species, little is known about the ecological aspects of the gekkonid lizard Hemidactylus frenatus in Colombia. In the present study the size at maturity, sexual dimorphism, reproductive activity, and diet composition of a population of this species in an urban locality of Northern Colombia were determined. We conducted eleven samplings from September 2011 to August 2012 in buildings of the municipality of Sincelejo. A total of 264 specimens H. frenatus were captured, 112 were adult females, 133 adult males and 19 juveniles. Males reach sexual maturity at a smaller size (snout-vent length) than females (males: 35.7 mm; females: 42.7 mm), also they are larger and have proportionally larger heads and mouths than females. Males were reproductive throughout the year; although testicular volume varied significantly between samples, this variation was not associated with body size and precipitation in the study area. Reproductive adult females were found during all the sampling period. Females have an invariable clutch size of two eggs and we found no differences in the diameter and weight of eggs in each oviduct. The diet of H. frenatus is varied, with Diptera, Hemiptera and Formicidae being the prey types with the greatest relative importance values. Individuals of both sexes consume a similar volume and number of prey. Thus, the studied population of H. frenatus has continuous reproductive activity and a generalist-opportunistic feeding behavior. The climatic conditions of the study area, environmental availability of prey and intrinsic features of this species appear to be responsible for their abundance and colonizing success in this and other localities.

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.

Body mass changes in male Daubenton's bats Myotis daubentonii (Chiroptera, Vespertilionidae) during the seasonal activity period

Mammalia ◽  
2004 ◽  
Vol 68 (4) ◽  
Author(s):  
Jorge A. Encarnação ◽  
Markus Dietz ◽  
Uwe Kierdorf ◽  
Volkmar Wolters
Keyword(s):  
Body Mass ◽  
Statistical Significance ◽  
Reproductive Activity ◽  
Activity Period ◽  
Adult Males ◽  
Body Mass Changes ◽  
Myotis Daubentonii ◽  
The Difference ◽  
Juvenile Males ◽  
Wallis Anova

Body mass changes of adult and juvenile male Daubenton’s bats were studied in a summer habitat in Hesse (Germany) in the years 1998-2001. Animals from the resident population were regularly captured along the flight path from April to October, and body mass was determined using a digital balance. Body mass of adult individuals differed significantly among fortnightly periods (Kruskal-Wallis ANOVA by ranks: H = 141.75, p < 0.001). Body mass increased significantly from the second half of April (median: 7.0 g) to the first half of May (median: 7.8 g). Between the second half of May and the first half of August, median body mass fluctuated between 7.8 g and 8.3 g. From the second half of July (median: 7.9 g) to the second half of August (median: 8.4 g), and the second half of September (median: 9.3 g) body mass again significantly increased. The highest median body mass (9.6 g) was recorded in the second half of October. Median body mass of juvenile males ranged between 6.5 g in the first half of July and 8.5 g in the second half of October. Differences in body mass over the studied period were significant (H = 21.70, p < 0.01). During the months July, August, and September, body mass of adult males was significantly higher than that of juveniles, whereas in October the difference was no longer of statistical significance. It is suggested that the decrease in body mass observed in some adult males in September was related to their reproductive activity.

Dispersal and site fidelity in Blue Grouse

1983 ◽  
Vol 61 (3) ◽  
pp. 570-573 ◽  
Author(s):  
Ian G. Jamieson ◽  
Fred C. Zwickel
Keyword(s):  
Site Fidelity ◽  
General Area ◽  
Adult Males ◽  
Same Sex ◽  
Breeding Sites ◽  
Sibling Pairs ◽  
Dendragapus Obscurus ◽  
Opposite Sex ◽  
Juvenile Males ◽  
Old Females

Ten years of banding and censusing data from Blue Grouse (Dendragapus obscurus) were analyzed with respect to dispersal of juveniles and site fidelity of yearlings and adults. Juvenile females dispersed farther than juvenile males. In sibling pairs of the same sex, brothers settled closer to one another than sisters. In sibling pairs with birds of opposite sex, females dispersed farther than males. Adult males first established territories close to where they had been sighted as yearlings, or nonterritorial adults, and most females returned in spring to the same general area where they had previously nested. Two-year-old females showed less fidelity to breeding sites they had used as yearlings than older females to sites they had used in previous years.

Pull Factors and Migration Preferences: Evidence from the Middle East and North Africa

2020 ◽  
pp. 019791832094982
Author(s):  
Jeremy Ferwerda ◽  
Justin Gest
Keyword(s):  
Middle East ◽  
North Africa ◽  
Rank Order ◽  
Geographic Distance ◽  
Pull Factors ◽  
Welfare Benefits ◽  
Liberal Democratic ◽  
National Characteristics ◽  
And Migration ◽  
Post Hoc

Which national characteristics do voluntary migrants prioritize when considering destinations? Although this question is salient for policymakers, extant studies face challenges when seeking to identify how various pull factors shape destination preferences. Surveys of migrants are typically conducted after they arrive, introducing selection bias and post-hoc reasoning. Moreover, desirable national characteristics tend to co-vary, implying that observed relationships with migration flows may be confounded. In this article, we identify the destination preferences of prospective migrants by drawing on a sample of 8,500 respondents from five sending states across the Middle East and North Africa. Prospective migrants completed a series of conjoint survey tasks in which they chose between two destinations with randomly varying characteristics. The results reveal a clear hierarchy of preferences, with prospective migrants placing the greatest priority on liberal democratic governance and employment prospects. The availability of welfare benefits acted as a secondary consideration, while geographic distance and co-ethnic stock did not strongly predict initial destination preferences. While the rank order of these considerations remains consistent across national samples, our results suggest that respondents from different economic and political backgrounds vary in how they navigate potential tradeoffs between national characteristics. These findings address post-arrival bias in extant studies by revealing prospective migrants’ preferences before they interact with the opportunity structures that facilitate and restrict entry into desirable destinations.

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