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.

Demographic characteristics of an unexploited population of fox squirrels (Sciurus niger)

1986 ◽  
Vol 64 (2) ◽  
pp. 512-521 ◽  
Author(s):  
Charles M. Nixon ◽  
Lonnie P. Hansen ◽  
Stephen P. Havera
Keyword(s):  
Population Change ◽  
Survival Rates ◽  
Breeding Period ◽  
Adult Males ◽  
Sciurus Niger ◽  
Recruitment Success ◽  
Adult Females ◽  
Fox Squirrels ◽  
Young Of The Year ◽  
Central Illinois

Demographic changes in an unexploited population of fox squirrels (Sciurus niger) were studied between 1971 and 1978 on 45.2 ha of upland forest in east-central Illinois. Known numbers of squirrels varied between 69 and 142. Adult squirrels (>15 months old) comprised >50% of the known population during the study, with annual survival exceeding 60%. Young-of-the-year made up <20% of the livetrapped population. Increasing populations were characterized by increases (P < 0.05) in numbers of yearling–adult males and young-of-the-year of both sexes. Recruitment depended on both immigration and on production of young by resident females. Recruitment success (proportion of new squirrels resident at least 6 months after initial capture) of immigrants was best for adults and yearlings and poorest for subadults. Adult female breeding success was highest in the winter and correlated negatively with the number of females conceiving the previous breeding period. The size and composition of the seed crop of trees in autumn had no effect (P > 0.05) on recruitment, conception, survival rates, or changes in overall density when at least some winter-storable tree seed was available. In most years, adult females were dispersed evenly, but adult males and young of both sexes showed an aggregated or random dispersion. Breeding rates for yearling females, recruitment success of immigrants and of juveniles born on the study area, and overall changes in squirrel densities between trapping periods correlated negatively (P < 0.05) with the number of adult females but not with the number of males or younger females. Interpretation of dispersion of adult females and the relationship of numbers of adult females to population change suggest that fox squirrels stabilize their numbers in the absence of obvious environmental stresses through aggressive interactions between adult females and resident young and immigrants of all ages.

Home-Range Size and Fidelity of Western Grey Kangaroos (Macropus Fuliginosus) Living in Remnants of Wandoo Woodland and Adjacent Farmland.

1992 ◽  
Vol 19 (2) ◽  
pp. 137 ◽  
Author(s):  
GW Arnold ◽  
DE Steven ◽  
A Grassia ◽  
J Weeldenburg
Keyword(s):  
Home Range Size ◽  
Home Ranges ◽  
Adult Males ◽  
The Core ◽  
Adult Females ◽  
Radio Transmitters ◽  
Core Areas ◽  
Males And Females ◽  
Eucalyptus Wandoo ◽  
Older Males

The home ranges were studied from 1977 to 1981 of western grey kangaroos (Macropus fuliginosus) living in a 300-ha remnant of wandoo [Eucalyptus wandoo] surrounded by farmland at Baker's Hill, Western Australia. The M. fuliginosus population varied from 140 to 200 animals during the study. In 1979, four females (>30 kg) and 2 adult males (31 kg and 47 kg) were fitted with radio-transmitters and their movements recorded. The home ranges of these animals varied from 39 to 70 ha; the average overlap in the area used during the day and that used at night was 16.4%. Many of the kangaroos fed on farmland at night. The night ranges of 51 marked kangaroos were recorded using a spotlight. The animals showed a strong fidelity to their home ranges. Only 3 males (about 5-yr-old) shifted their night ranges; the centres of the ranges moved only 600-800 m. Older males had significantly larger night ranges than younger males and females. Individual females and the younger males showed preferences for using particular access points to get onto farmland; the older males showed no preferences. The core areas of the night ranges of many adult females overlapped closely in 'groups', but there was no evidence of 'mob' home ranges that were socially separated.

scholarly journals Home range of the Tropidurid lizard Liolaemus lutzae: sexual and body size differences

1999 ◽  
Vol 59 (1) ◽  
pp. 125-130 ◽  
Author(s):  
C. F. D. ROCHA
Keyword(s):  
Body Size ◽  
Home Range ◽  
Mutual Exclusion ◽  
Home Range Size ◽  
Range Size ◽  
Home Ranges ◽  
Adult Males ◽  
Adult Females ◽  
The Mean ◽  
Janeiro State

The home range of the Tropidurid lizard Liolaemus lutzae, an endemic species of the costal sand dune habitats of Rio de Janeiro State, was studied in the beach habitat of Barra de Maricá restinga, Maricá County. Home ranges were studied using a mark-recapture technique in a delimited area at the beach habitat. I considered for estimates and analysis the home ranges of those lizards with a minimum of four positions. The size of L. lutzae home ranges varied according to the segment of the population. The mean home range size of adult males (x = 59.8 ± 33.7 m²) was significantly larger than that of adult females (x = 22.3 ± 16.1 m²). Juvenile mean home range size was significantly smaller than that of adult males, but did not differ from that of adult females (t = 1.058; p = 0.149). The overlap between male home ranges was usually low (3.6%), being in general only peripheral. Conversely, there was a considerable overlap between home ranges of adult females with those of adult males, the home range areas of two or three females being enclosed in the home range of one adult male. The small overlap between home ranges of adult males suggested mutual exclusion. The observed between-sex differences in the size of L. lutzae home range may be explained by the sexual dimorphism in body size in this species, and by the need of adult males to establish larger areas so as to include many females in their areas, during the reproductive season. The differences in home range along ontogeny probably result from differences in body size of the different segments of the population, due to trophic differences (carnivory and herbivory levels), and the dispersal of young after birth. Because L. lutzae is omnivorous, but primarily herbivorous when adult, and due to its sit-and-wait foraging behavior (mainly on arthropods), it does not need to move around over large areas to find food, which in turn reduces the area necessary for it to live.

The population pattern of Miniopterus schrebersii (Chiroptera) in north-eastern New South Wales

1966 ◽  
Vol 14 (6) ◽  
pp. 1073 ◽  
Author(s):  
PD Dwyer
Keyword(s):  
New South ◽  
New South Wales ◽  
Population Characteristics ◽  
Adult Males ◽  
Age Classes ◽  
Adult Females ◽  
South Wales ◽  
Wide Range ◽  
North Eastern ◽  
Population Pattern

In north-eastern New South Wales Miniopterus schreibersii is found at a wide range of cave and mine roosts as colonies that may include up to several thousands of individuals. Between April 1960 and September 1963 a field study of the biology and population characteristics of this species was carried out. Field criteria permitting aging of individuals were developed. Age classes considered were juveniles (< 9 months), yearlings (9-21 months), and adults (> 21 months). Seasonal changes in numbers, and in the sex and age composition of colonies were followed in detail at several roosts and comparative information was obtained at others. Movement patterns were assessed by a marking and recapture programme in which 1365 recoveries were obtained from a marked (toe clips and bands) population of 8775. Conspicuous sex or age biases or both were shown to exist in clusters of M. schreibersii at specific roosts and it was suggested that clustering in this species functions, in part, as a social spacing mechanism. Segregation of different sex or age classes at specific colonies permitted classification of colonies as (1) maternity colonies in which adult females and their young predominate, (2) "adult" colonies which are predominantly adult, or adult and yearling, in composition, and (3) "juvenile" colonies in which juveniles, or juveniles and yearlings, are almost prevalent. The observed social biases of colonies appeared to be related to particular phases of the reproductive cycle. Certain adult colonies were interpreted as important sites of copulatory behaviour. Recovery data for two of these mating colonies showed that adult females were more transient members of the colony than adult males. Juveniles are often well represented at adult colonies in the autumn, and during this season their presence may be correlated with a drop in the abundance of older males.

scholarly journals Home range, movements, and denning chronology of the Grizzly Bear (Ursus arctos) in west-central Alberta

2014 ◽  
Vol 128 (3) ◽  
pp. 223 ◽  
Author(s):  
Karen Graham ◽  
Gordon B. Stenhouse
Keyword(s):  
Home Range ◽  
Ursus Arctos ◽  
Home Range Size ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Adult Males ◽  
Gps Collars ◽  
Recovery Planning ◽  
Adult Females ◽  
West Central

An understanding of the natural history of the Grizzly Bear (Ursus arctos) is important for recovery planning. We present data on home range size, movements and denning chronology collected using Global Positioning System (GPS) collars on Grizzly Bears in west-central Alberta. Mean annual kernel estimates for adult (1034 ± 656 (SD) km2) and subadult (1298 ± 1207 km2) males were larger than those for females with cubs of the year (213 ± 212 km2) and lone adult females (337 ± 176 km2) but not different from sub-adult females, females with yearlings, or females with ≥ 2-yr old cubs (P > 0.05). Mean rates of movement among female age–reproductive classes were different from each other (Z9 < 2.70, P > 0.05) but not different from sub-adult males (Z9 < 2.70, P > 0.05). Rates of movement of adult males were significantly different only from those of females with cubs of the year (Z9 = 3.94, P = 0.001). The greatest amount of movement occurred in June and the least in October. Bears traveled fastest in the morning and evening and slowest at night. Pregnant females had the longest denning period (175 days, ± 16 days SD). No difference was detected in denning duration among the remaining five age–sex–reproductive classes (P > 0.05). GPS collars provided large location datasets from which accurate home range estimates, hourly movement rates, and precise denning dates were determined. Examining similarities and differences in the basic biology of Grizzly Bears from various locations will improve our understanding of the plasticity of this species and the potential impacts of habitat and climate change.

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.

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.

Spatial dynamics of fox squirrels (Sciurus niger) in fragmented landscapes

1995 ◽  
Vol 73 (11) ◽  
pp. 2098-2105 ◽  
Author(s):  
B. Forrest Sheperd ◽  
Robert K. Swihart
Keyword(s):  
Home Range ◽  
Agricultural Landscape ◽  
Spatial Dynamics ◽  
Growing Season ◽  
Home Range Size ◽  
Range Size ◽  
Home Ranges ◽  
Sciurus Niger ◽  
Continuous Forest ◽  
Fox Squirrels

We examined the spatial dynamics of fox squirrels (Sciurus niger) occupying 12 woodland sites in a predominantly agricultural landscape of west-central Indiana. The 12 sites represented woodlands of varying degrees of isolation and size. Forty-nine adult fox squirrels were fitted with radio collars and monitored from May 1993 through September 1994. No movements of collared adults were observed between wooded sites during the study, although squirrels traveled 200–500 m from woodlots along hedgerows, and 2.6% of observations occurred in agricultural fields. Multiple regression revealed a positive linear relationship between home-range size and woodland size, with larger home ranges in the growing season. Home-range size was not related to woodland isolation, squirrel density, or sex. We found no evidence of spatial interactions between pairs of squirrels (i.e., male–male, male–female, female–female) at resolutions of 20, 40, or 100 m. Excursions beyond a core area were of relatively greater magnitude for squirrels occupying continuous forest. Agriculturally induced fragmentation of forests appears to restrict movements of adult fox squirrels, despite the well-documented ability of the species to persist in such a landscape.

scholarly journals Site fidelity and effects of body mass on home-range size of Egyptian mongooses

1994 ◽  
Vol 72 (3) ◽  
pp. 465-469 ◽  
Author(s):  
F. Palomares
Keyword(s):  
Home Range ◽  
Body Mass ◽  
Site Fidelity ◽  
Home Range Size ◽  
Range Size ◽  
Adult Males ◽  
Spatial Strategies ◽  
Adult Females ◽  
Egyptian Mongoose ◽  
Herpestes Ichneumon

Home-range size has been found to be related to body mass of some animals both across species and within species when the spatial strategies of the sexes differ. I studied home-range size in a polygynous carnivore, the Egyptian mongoose (Herpestes ichneumon), and compared observed home-range size with predictions based on body mass. First, I tested whether mongooses actually exhibited site fidelity (for daily and multiday periods). Mongooses always showed site fidelity for a multiday home range, but in only 59% of the cases for daily home range. Adult males exhibited less daily site fidelity than did adult females or young. Multiday home-range size was similar among age–sex classes, but males had significantly more core areas than females or young. Multiday home-range size was positively correlated with body mass for adult males (r2 = 0.98, P = 0.0122) and negatively correlated with body mass of adult females (r2 = 0.40, P = 0.0374). Differences in these relationships and daily site fidelity between adult males and females suggest that the spatial strategies of male and female Egyptian mongooses are different, with the larger females defending the areas richer in resources and the larger males having more access to females.

scholarly journals Growth curve for height at withers and body length of Mangalarga Marchador horses

2020 ◽  
Vol 50 (12) ◽  
Author(s):  
Tales Jesus Fernandes ◽  
Felipe Amorim Caetano de Souza ◽  
Rafaela Aparecida Ribeiro ◽  
Fabiana Oliveira Cunha ◽  
Sarah Laguna Conceição Meirelles ◽  
...  
Keyword(s):  
Body Length ◽  
Logistic Model ◽  
Model Parameters ◽  
Adult Males ◽  
Age Classes ◽  
Adult Females ◽  
Computational Work ◽  
Quadratic Response ◽  
Length Data ◽  
Over Time

ABSTRACT: This study aimed to evaluate the logistic and quadratic response plateau models to describe the growth of Mangalarga Marchador horses to identify the model that best describes growth for the variables height at withers and body length. Data were used from 230 horses aged 6 to 176 months, divided by sex and 16 age classes. All computational work was performed using R statistical software. The logistic model was the best suited to express growth in height at withers and body length of male and female Mangalarga Marchadors aged 6 to 176 months. This allowed creating a table of reference values for these measurements over time based on the confidence interval of the model parameters. Estimates of height at withers obtained by the logistic model ranged from 144 to 154 cm in adult males and from 143 to 151 cm in adult females. For body length, values ranged from 146 to 156 cm in adult males and 143 to 156 cm in adult females. Females achieved stability in both height at withers and body length at earlier ages than did males.

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