Minimum Home Range Size Research Articles

Habitat restoration is the greatest challenge for population recovery of Hainan gibbons (Nomascus hainanus).

Hainan gibbons are among the world's most critically endangered primates, with a remaining population of only 35 individuals distributed across 5 social groups in the Bawangling Branch of the Hainan Tropical Rainforest National Park, China. Habitat conversion and forest fragmentation over the past 40 years have reduced their geographical distribution by 95%. In the absence of a quantitative assessment of the availability of remaining suitable habitat, it is unclear whether this species can survive to the end of this century. We used behavioral observations, ArcGIS, remote sensing, stereo optical imagery, and MaxEnt modeling to identify patterns of Hainan gibbon range use and compare changes in the distribution of suitable forest types and areas of forest fragmentation over the past 20 years (2000-2020). The results indicate that the combined range of the 5 extant Hainan gibbon groups totaled 14.89 km2 . The home range of the smallest group (Group E, 3 individuals) was 1.51 km2 , which likely represents the minimum home range size for this species. The remaining area of highly suitable and moderately suitable habitat totals 26.9 km2 . However, habitat connectivity across the gibbon range is very low (less than 0.5), limiting the ability of Hainan gibbons to move between forest patches. The results of this study indicate that the availability of suitable habitat in Bawangling is insufficient to allow for future Hainan gibbon population growth. Therefore, immediate action must be taken to restore, reforest, and establish ecological corridors to reconnect areas of suitable habitat for these critically endangered gibbons.

A Camera-Trap Home-Range Analysis of the Indian Leopard (Panthera pardus fusca) in Jaipur, India.

Simple SummaryJhalana Reserve Forest (JRF) is engulfed by the city of Jaipur, India, with a human population of 3.9 million. Due to a continuum between human habitation and forests, frequent interactions with wildlife are inevitable. The leopard is the apex predator in JRF, sharing a habitat and resources with the human population. It is imperative to understand and study the leopard ecology to design and implement conservation strategies. We used a simple but effective and non-invasive technique—camera trapping—to identify leopards individually. The data analyzed using the minimum convex polygon (MCP) 100% method helped us estimate their home ranges. The use of camera traps was preferred over radio collaring, considering the permits of the Forest Department. We observed that males have larger home ranges than females. The females established their home ranges in the core area and on the fringes of the reserve. We discovered familial (mother and daughter) establishment of overlapping home ranges adjacent to one another. Three females who established themselves on the fringes were successful mothers raising cubs during the study period. The human population in the villages on the fringe areas share resources with the leopards, demonstrating that coexistence with predators is possible in a human-dominated landscape.The suitability of the camera trap–retrap method was explored for identifying territories and studying the spatial distribution of leopards (Panthera pardus fusca) in the Jhalana Reserve Forest, Jaipur, India. Data from two years (November 2017 to November 2019, N = 23,208 trap-hours) were used to provide estimates of minimum home-range size and overlap. We conducted home-range analysis and estimation, using the minimum convex polygon (MCP) method with geographic information system (GIS) tools. We are aware of the limitations and advantages of camera trapping for long-term monitoring. However, the limitations of the research permit allowed only the use of camera traps to estimate the home ranges. A total of 25 leopards were identified (male = 8, female = 17). No territorial exclusivity was observed in either of the sexes. However, for seven females, we observed familial home-range overlaps wherein daughters established home ranges adjacent to or overlapping their natal areas. The median home range, as calculated from the MCP, was 305.9 ha for males and 170.3 ha for females. The median percentage overlap between males was 10.33%, while that between females was 3.97%. We concluded that camera trapping is an effective technique to map the territories of leopards, to document inter- and intraspecific behaviors, and to elucidate how familial relationships affect dispersal.

Small Mammal Communities: Diversities, Seasonal and Temporal Distribution in Each Forest Type, University of Phayao Plant Genetic Conservation Area, Thailand

Small mammal communities were studied over 12 months in three dry tropical forest habitats in the University of Phayao Plant Genetic Conservation Area, Phayao Province, Thailand. Traps were set for three days each month, and trapped animals were marked and released. Data were collected on species, age, body mass, and trap location, allowing for the determination of population age structure through time, minimum home-range sizes, biomass, and com- munity diversity indices. Six species of Rodentia and one each of Scandentia, Lagomorpha and Carnivora were recorded in 1,047 captures of 371 individuals over 3,528 trap nights (a 29.7% capture rate). The four most common species caught from all sites were Maxomyssurifer, Tupiaglis, Rattusrattus and Leop- oldamyssabanus, with M. surifer the most common species in all forest types. There was significant variation across forest type and season in the age of animals caught, their density, and their mass, but not in community structure or sex ratios. In all forest types, minimum home range sizes were larger in the cold and hot seasons than in the rainy season. The dry dipterocarp forest supported the highest diversity of small mammals. Small-mammal community diversity was positively correlated with forest heterogeneity.

Ecology of the ocelot (Leopardus pardalis) in the Atlantic Forest of Southern Brazil

The ocelot Leopardus pardalis is a medium-sized Neotropical spotted cat with a wide geographic range. The present study was conducted in a reserve in an Atlantic Forest area in southern Brazil, and provided information on ocelot ecology through photographic records. Density estimated by the half of the mean maximum distance moved method resulted in 0.04 ocelots per km2. The minimum home range sizes were obtained by the minimum convex polygon method and were in agreement with other studies for the males recorded. Our female’s home range size was smaller than ranges reported elsewhere. The nocturnal pattern recorded is probably related with prey activity, since it is suggested that ocelots adjust their movements to the probabilities of encountering local prey, or with an evolutionary factor, aiming to avoid competition/predation with larger cats. The low density observed could be a consequence of the conditions of the study area, small and isolated, which indicates the necessity for larger reserves and mechanisms to connect isolated populations.

Home range and spatial organisation of stoats (Mustela erminea), ferrets (Mustela furo) and feral house cats (Felis catus) on coastal grasslands, Otago Peninsula, New Zealand: Implications for yellow‐eyed penguin (Megadyptes antipodes) conservation

This radio‐tracking study reports the home range and spatial organisation of 12 stoats (Mustela erminea), 21 feral ferrets (Mustela furo) and 11 feral house cats (Felis catus) in coastal grasslands surrounding yellow‐eyed penguin (Megadyptes antipodes) breeding colonies, Otago Peninsula, South Island, New Zealand. Fully revealed ranges averaged 133 (±52 SD) ha for 6 male stoats; 83 (±73 SD) ha for 2 female stoats; 163 (± 50 SD) ha for 6 male ferrets; 135 (±44 SD) ha for 10 female ferrets; 207 (±99 SD) for 7 male cats; and 148 (± 63 SD) ha for 3 female cats. Males had larger ranges than females, and the larger predators ranged over greater areas than the smaller predators. Mustelids did not have intrasexual territorial spacing systems. Similarly, mustelid and cat ranges overlapped extensively, though stoats may avoid ferrets and/or cats by using different micro‐habitats. An example on how the logic of this argument applies to protect yellow‐eyed penguins threatened by stoats or ferrets and cats follows: based on minimum home range size, control stations should be placed less than 638 and 964 m apart respectively to ensure all individual predators are at risk of being killed. Investigation of the number of control stations per home range to ensure all trappable predators are killed would allow improved cost‐effectiveness of control programmes. As an interim protocol we recommend control stations spaced 286 and 432 m apart on trapping grids to control stoats and ferrets/cats repectively.

Structure, dynamics, home range and activity pattern of mixed-species bird flocks in a montane alder-dominated secondary forest in Ecuador

ABSTRACTTwo mixed-species bird flocks were studied in a high-altitude humid secondary forest in the Andes of Ecuador. Birds were mist-netted and colour-ringed for individual identification. The flocks (A and B) were followed to record structure, dynamics, home range and activity pattern. All observations of the two flocks studied included members from all vertical levels, which is different from flocks of Amazonia. In two nucleus species, some individuals alternated between the flocks, a feature not previously reported. Various tanagers were loosely associated, joining and leaving flocks. Minimum home-range sizes of flocks A and B were 4.2 ha and 7.8 ha, respectively. Some individuals of two species used an area encompassing the home ranges of both flocks. Mean flock sizes in A and B were 21.7 and 44.7 individuals, whereas the mean numbers of species were 13.7 and 21.7, respectively. Number of species and individuals were high compared to even most lowland flocks. Altogether, mixed-species flocks in different habitats and at various latitudinal and altitudinal sites appear to have some features in common, but others are highly distinct. Compared to the great stability of Amazonian flocks, some high-altitude flocks of secondary forest in the Andes appear to be more dynamic and unstable.

Forest fragmentation and the conservation of raptors: A survey on the island of Java

The natural forest cover of Java is now reduced to small, very isolated fragments which remain the only suitable habitats for a number of endemic species. The aim of this survey was to assess the distribution and population size of the ten forest Falconiforms, including the endangered Java hawk eagle, Spizaetus bartelsi. Five of the main forest reserves, ranging from 5 to 500 km 2, were studied. Among the ten species, four are restricted to low altitude forest (below 1500m) and are now very local because of its disappearance. Six species are making wide use of secondary habitats around forest reserves and are thus less susceptible to forest alteration and fragmentation. All the forest raptors here show some attributes of the so-called ‘syndrome of insularity’, i.e. wide distribution and habitat niche as well as rather high densities. So sizable populations can survive in relatively small patches. But there is a positive correlation between the size of the reserve and the abundance index of all species. The two forest hawk eagles ( S. bartelsi and Hieraaetus kienerii) may have minimum home range sizes of about 20–30 km 2 and may not survive in forest patches smaller than 20 to 100 km 2. Their present population of at least 8 to 10 pairs per reserve may be considered as the minimum critical size for a viable population. Reserves of less than 300 km 2 cannot include viable populations of every forest raptor. So additional well protected reserves must be added to the present network, to provide a better prospect of survival for all the species. Seven other, open or aquatic species, formerly known from Java, seem now to have decreased dramatically and some of them may be on the verge of extinction on the island.

Population density, home range size and spatial organization of the Cape clawless otter, Aonyx capensis, in a marine habitat

In a protected area on the southern coast of South Africa, holts (dens) of the Cape clawless otter were spaced at intervals of 470 m and spraints (faeces) were concentrated in the vicinity of the holts. Population density estimates for separate sections of coast were in close agreement, and the mean estimate for the study area was one otter per 1.9 km of coast. The minimum home range size of an adult female was 14.3 km of coast, a 7.5 km central section constituting her core area. A radio‐tracked adult male had a minimum home range size of 19.5 km of coast and a centrally located 12.0 km core area. The known home ranges of four adult males overlapped completely and males were observed foraging together, indicating a clan‐type of social organization.

Movements and Cover Preferences of Pheasants in South Dakota

Movement trends and cover preferences of 13 ring-necked pheasant (Phasianus colchicus) hens, 8 of which produced broods, were studied by radiotelemetry from June to October in 1969 and 1970. The average minimum home-range size was 90 acres (sD ? 48), the length of major axis of home ranges was 0.71 ? 0.28 mile, and the average minimum activity radius was 0.16 ? 0.09 mile. Home ranges were smallest during the peak of hatch (15-30 June) and in October, and largest during the sown small-grain harvest (16-31 August). Alfalfa was the most extensively used cover type both day and night, and was preferred in all months of study. Sown small-grain fields, corn fields, and shelter belts were intermittently preferred for nesting or roosting. J. WILDL. MANAGE. 37(4):454-461 Cover types used by pheasant broods have been studied by means of roadside and random field observations (Kozicky and Hendrickson 1951, Hammer 1965, Linder and Agee 1965). Since the development of radiotracking systems (LeMunyan et al. 1959, Marshall 1960, Cochran and Lord 1963) and radiotelemetry procedures (Marshall and Kupa 1963), biologists have been able to collect detailed data on activities and seasonal movements of individual pheasants (Kuck et al. 1970, Carter 1971). Because little is known about cover preferences and movements of hens and broods after nesting, this study was aimed at determining (1) movement patterns of hens and their broods on agricultural land and (2) preferences for various habitat components at different periods following nesting. The South Dakota Agricultural Experiment Station, Brookings, provided funds for this project (S-521). V. C. Ellerbruch developed the radio transmitters and the receiving system, W. L. Tucker guided the statistical analysis, D. P. Oschner wrote the computer plotter program, and J. M. Gates gave valuable advice during the study.