Home range and movements of radio-tracked estuarine crocodiles (Crocodylus porosus) within a non-tidal waterhole

2008 ◽  
Vol 35 (2) ◽  
pp. 140 ◽  
Author(s):  
Matthew L. Brien ◽  
Mark A. Read ◽  
Hamish I. McCallum ◽  
Gordon C. Grigg

We radio-tracked five male and eight female estuarine crocodiles (Crocodylus porosus) in a non-tidal waterhole in Lakefield National Park in northern Queensland during the late dry/mid-wet season (2003–04) and the following dry season (2004). Individual crocodiles occupied larger home ranges (River Channel Areas (RCA) during the late dry/mid-wet season (10.64 ± 2.86 ha) than in the dry season (3.20 ± 1.02 ha), and males occupied larger home ranges (23.89 ± 2.36 ha) than females (5.94 ± 1.34 ha) during the late dry/mid-wet season. There were no obvious differences in home range between sexes during the dry season. During the late dry/mid-wet season, adult males often travelled long distances along the waterhole while females moved less. During the dry season, movement patterns were quite variable, with no clear difference between sexes. All crocodiles were most active from late afternoon (1500–1800 hours) until midnight. Individual home ranges (RCA) overlapped considerably during the late dry/mid-wet season. The extent of home-range overlap between three adult males and the number of times they either passed each other or were located near each other was particularly striking. Previous research has come to conflicting conclusions about the extent of territoriality in wild estuarine crocodiles, although it has been widely believed that males are highly territorial. The findings imply that large adult male estuarine crocodiles are not highly territorial in non-tidal freshwater systems that are geographically confined.

2000 ◽  
Vol 78 (12) ◽  
pp. 2087-2095 ◽  
Author(s):  
Michael J Chamberlain ◽  
Charles D Lovell ◽  
Bruce D Leopold

Recently, coyotes (Canis latrans) have expanded their range to include most areas of the southeastern United States. However, most research on coyotes has been conducted in western and northern regions of North America. We radio-monitored 38 adult coyotes from 1993 to 1997 in central Mississippi. Home-range sizes (P = 0.681) and core-area (area of concentrated use) sizes (P = 0.736) were similar across seasons, but females maintained larger home ranges (P = 0.006) and core areas (P < 0.001) than males. Male-male, female-female, and male-female home-range overlap was greatest during whelping and pup rearing. Except for mated pairs, core-area overlap was negligible across all seasons for adults maintaining neighboring home ranges. Coyote habitat selection varied across spatial scales, though selection was similar between males and females at all scales. Coyote movement rates differed (P < 0.001) temporally, being highest during nocturnal periods. Overall, the highest movement rates for the monitored population were observed for females during summer. Two males and 2 females were suspected of forming pair bonds and frequently traveled together within shared home ranges, as did 2 adult males. Our data indicate that interactions among individual adults are influenced by sex, as most confirmed instances of direct contact occurred between pairs or suspected social groups. In our study area, neighboring adult coyotes exhibited territoriality at the core-area level.


2000 ◽  
Vol 27 (1) ◽  
pp. 49 ◽  
Author(s):  
Stephen M. Jackson

The home-range of the mahogany glider was estimated, and its social behaviour examined, by following radio-collared animals over a two-year period within an area of continuous habitat and an adjacent area of fragmented habitat. The average home range within the continuous habitat was 19.25 ha for males and 20.34 ha for females, with male and female pairs occupying a combined area of 23.15 ha. In contrast, the average home range in the fragmented habitat was 11.05 ha for males and 6.80 ha for females, with a combined home-range of male and female pairs being 11.60 ha. The average overlap of the home ranges of paired males and females was 85.9%, compared with approximately 11% for non-paired individuals, which suggests that mahogany gliders are socially monogamous. For a total of 46 nights on which gliders were considered to behave normally for the entire night, the average foraging distance was 1506 m (range 590–3420 m) with no significant difference between males and females in either the continuous or fragmented habitat. There was, however, a significant difference in the distance individuals travelled during different times of the year, with longer distances being travelled during late dry season/wet season and shorter distances during the early to mid dry season. Mahogany gliders also travelled further when there was a high availability of nectar and pollen than when there was lower availability. A total of 83 dens (tree hollows) were recorded for the mahogany glider, with the poplar gum, Eucalyptus platyphylla, forest red gum, Eucalyptus tereticornis, and Clarkson's bloodwood, Corymbia clarksoniana, being most used.


2021 ◽  
Vol 14 ◽  
pp. 194008292110261
Author(s):  
Hervé Lormée ◽  
Rachel Berzins ◽  
Vincent Rocheteau ◽  
Fran De Coster ◽  
Thomas Denis ◽  
...  

Cracidae is the most threatened avian family in the Neotropics, mainly because of habitat destruction, heavy hunting pressure and poaching. In French Guiana, Black Curassows are heavily hunted, although basic knowledge of the ecological and demographical traits of the species remains limited. Such a gap prevents any attempt to assess the impact of hunting and to help stakeholders to develop proposals ensuring hunting sustainability. The spatial relationship between animals and their habitat is important for conservation management, being related to population densities through complex patterns. Here, we report on a radio-tracking study of Black Curassows in tropical primary rainforest, in Nouragues National Reserve, French Guiana. The aims of the study were to estimate home range size and its variation across seasons, and to quantify movement patterns of the birds. We captured and fitted VHF tags to four adults, and tracked them for 10 to 21.5 months. Daily movements were recorded, and home ranges estimated using the Kernel Density method, for two consecutive wet seasons and one dry season. Using 95% and 50% Kernel densities, the average annual home range and core area were 96.3± 32.6 ha (SE) and 22.8 ± 2.8 ha respectively. Home ranges appeared spatially stable over the two years, and overlapped between neighbouring groups. During the dry season, Black Curassows did not migrate but tended to enlarge their home range, with greater daily movements and higher home range overlap. Although additional data are still needed, our results can help to improve the knowledge and management of this poorly studied species.


2007 ◽  
Vol 55 (3) ◽  
pp. 185 ◽  
Author(s):  
Meredeth Brown ◽  
Susan M. Carthew ◽  
Steven J. B. Cooper

Several Australian arboreal marsupials have been reported to show variation in mating system across populations, but most previous studies have not included genetic analyses to confirm the observations. Our aim was to test the hypothesis that monogamy was the predominant mating system in a population of yellow-bellied gliders (Petaurus australis) in south-western Victoria, using a combination of behavioural observations and molecular genetic analyses. Home-range overlap, cohesiveness of pairs, rates of den site co-occupancy and location of den trees within the home ranges of 13 adult gliders were determined via radio-tracking. A monogamous social system predominated, demonstrated by extensive home-range overlap between cohabiting adult males and females (40–100%) and little home-range overlap between adjacent territories (<14%). Males spent ~55% of their active time within 25 m of their female partners and 55–85% of their sleeping time in dens with their female partner. The parentage of all juveniles spotlighted within the 400-ha study area was analysed using five microsatellite DNA markers. Of 37 individuals genotyped, eight of 13 juveniles were assigned both social parents as true parents with ≥80% confidence. These results suggest that social and genetic monogamy predominated in this population of yellow-bellied gliders.


2004 ◽  
Vol 31 (5) ◽  
pp. 495 ◽  
Author(s):  
Winston R. Kay

VHF radio-tags were attached to 16 estuarine crocodiles that were tracked between October 2001 and May 2003. Male (n = 12) and female (n = 4) crocodiles exhibited distinctly different patterns of movement. Females occupied a small core linear range (1.3 ± 0.9 km) on the main river channel during the dry season and moved up to 62 km to nesting habitat during the wet season, returning to the same core area the following dry season. They occasionally made excursions away from their core areas during the dry season. Males moved considerable distances along the Ord River throughout the year. The largest range recorded was 87 km for a 2.5-m juvenile male. However, ranges of males did not appear to be related to body size, with the largest two ranges being recorded for the smallest (2.5 m) and largest (4.3 m) males tagged. Rates of movement of males did not differ significantly between three size classes of males but there were significant seasonal differences, with the highest mean rates of movement occurring during the summer wet season (4.0 ± 5.4 km day–1). However, males were quite mobile during the dry season and the highest rate of movement detected was 23.3 km day–1 for a 4.3-m male at the end of July. The highest rate of sustained movement was 9.8 km day–1 for a translocated 2.6-m juvenile male, which travelled 118 km in 12 days to return to the area of its capture. Neither males nor females showed exclusive habitat preferences for any of four broad riverine habitats identified on the Ord River. However, the three largest males had activity centres that they returned to frequently despite numerous excursions throughout the year, both up- and downriver. Males had substantial range overlaps with no obvious spatial partitioning, suggesting that territoriality is not an important behavioural characteristic of free-ranging male crocodiles along the Ord River.


2001 ◽  
Vol 49 (1) ◽  
pp. 17 ◽  
Author(s):  
Kirstin I. Long

This study investigated the mating system of the long-nosed potoroo, Potorous tridactylus, by examining temporal associations between individuals, and patterns of home-range overlap. Six adult females and five adult males were radio-tracked at intervals throughout the 24-h day from December 1996 to March 1997 in south-western Victoria. Home ranges of individuals overlapped with multiple members of each sex; however, intrasexual overlap was significantly lower than intersexual overlap. When data from consecutive radio-tracking sessions were examined, the locations of resting or ‘squat’ areas were identified. These were almost entirely intrasexually exclusive. Male home ranges overlapped the squat areas of one or more females; however, males did not regularly associate with every female whose squat area they overlapped. In three of four cases, pairs of a male and a female associated regularly and spent a greater proportion of time in close proximity to each other than would be expected if they were moving at random. In the past it has been assumed that males monitor the sexual status of females while they rest in squats. If this is the case, the mating system of long-nosed potoroos will be largely dictated by the number of female squat areas that a male is able to regularly monitor within his home range.


2003 ◽  
Vol 30 (6) ◽  
pp. 593 ◽  
Author(s):  
Simon C. Stirrat

Radio-tagged male and female agile wallabies were tracked in the wet and dry seasons at a site in Darwin, Northern Territory, and home ranges estimated using a kernel-based estimator. Home-range size (95% contour) was larger in the dry season, when food quality was poorer, and males had larger home ranges than females. Core range size (55% contour) did not differ between seasons or sexes. Average male and female home-range sizes in the wet season were 16.6 ha and 11.3 ha respectively. Wet-season core range sizes were 4.8 ha and 3.2 ha respectively. Average male and female home-range sizes in the dry season were 24.6 ha and 15.3 ha respectively, and dry-season core range sizes were 5.1 ha and 4.0 ha respectively. Home-range size for both sexes varied in the two seasons; the smallest and largest female home ranges were 6.3 ha and 24.0 ha respectively, while male home-range size varied from 7.6 ha to 38.2 ha. Seasonal differences in home-range size can be attributed to expansion of night-time foraging areas in the dry season when good-quality food resources were in short supply. Habitat use also differed between seasons. In the dry season more fixes were located in forest areas, particularly in the evening, when wallabies foraged in forest areas for alternate food resources including browse, leaf litter, flowers and fruits of rainforest tree and shrub species. In the wet season, wallabies emerged from day-time resting areas earlier in the afternoon and therefore more wallabies were located in open areas grazing on high-quality herbage in the evening.


1999 ◽  
Vol 26 (3) ◽  
pp. 263 ◽  
Author(s):  
Jane Melville ◽  
Roy Swain

We studied the home ranges of the alpine skink, Niveoscincus microlepidotus, in an alpine transition zone on Mt Wellington, Tasmania, over a 5-month period to examine seasonal patterns in the home-range characteristics of four male, four female and two sub-adult juvenile lizards. Home-range sizes and activity patterns within these were quantified. Adult males had significantly larger home ranges with more activity centres than adult females; most activity centres were clearly synonymous with basking sites and were defended by overt aggressive behaviour. Home ranges of males showed little overlap and no seasonal variation while those of femals were unusual amongst reptiles in showing extensive overlap and seasonal change in size. Ranges were smallest in spring when all females were pregnant and were smallest in summer when only one female was pregnant. Range overlap ensured that all females studied had potential access to at least two males. Juveniles had no defined home ranges and appeared to be transients.


Koedoe ◽  
2003 ◽  
Vol 46 (2) ◽  
Author(s):  
G. Matipano

Differences in woody browse selection between hand-raised (and subsequently released), boma-adapted and wild black rhinoceros, Diceros bicornis, L. were studied in Matusadona National Park between December 1999 and July 2000. Boma-adapted rhinoceros were animals that were subjected to hand-raising and were kept in bomas (enclosures) over night. The feeding behaviour was different between the three rhinoceros groups. All rhinoceros groups utilised and selected for a few browse species in common, at different preference levels in the same habitat types according to season. Wild rhinoceroses browsed most in Colophospermum-Terminalia-Combretum woodland in the wet season and in thicket in the dry season. Hand-raised rhinoceroses browsed most in Colophospermum-Terminalia-Combretum woodland and boma-adated rhinos in thickets in both the wet and the early dry seasons. Hand-raised and bomaadapted rhinos changed their habitats less for browse selection than wild rhinos. This can be ascribed to a relative restriction of home range in the hand-raised group and a herding effect for the boma-adapted animals. These situations might have accounted for differences in seasonal browse selection by the rhinoceros groups.


1983 ◽  
Vol 53 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Hugo Jachmann

Using a recognition file that was compiled during the study, information on movements of individually known elephants was collected over two periods, one of three and one of eight months, in 1978 and 1981/82, respectively. There appeared to be a relationship between the number of animals in the family unit and the size of the home range/activity area, probably as a result of food competition between the members of a unit. Since 1978 the size of the home range/activity area had decreased in general, as a result of compression by illegal activity. Dry-season home ranges of family units appeared to be rather stable over longer periods and larger than the wet-season home ranges that were situated along the river Lingadzi. Dry-season home ranges of bulls only lasted throughout a single dry season. During the wet season bulls ranged over an extended area. In the later part of the dry season, elephant movements were determined by salt licks and the remaining water holes with a relatively high conductivity, at a distance of the river Lingadzi. The social structure of the family units that made up a kin-group determined the time spent with each other and also appeared to influence the actual size of the home range.


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