Fixed Kernel Density Estimator Research Articles

Home ranges and activity of Garden Dormice in the Harz Mountains, Germany

For the conservation of endangered species, a good knowledge of their biology is essential. However, due to the secluded lifestyle and nocturnal activity of the Garden Dormouse (Eliomys quercinus), comprehensive research on these small mammals is difficult, resulting in a lack of data. Little is known about the habitat requirements of Garden Dormice in forest habitats. Radio tracking was used to analyze movement patterns to identify specific features of their habitat in the Harz Mountains National Park in Germany (~700 m a.s.l.). Four individuals (2 females, 2 males) were tracked during 11 weeks from May until September 2021. Home ranges were calculated using minimum convex polygon (MCP) and fixed kernel density estimation (KDE) methods. Home range sizes (100% MCP) of males were between 0.58 ha and 7.62 ha and of females between 3.63 ha and 6.39 ha. The size of the core areas (65% KDE) was 0.25 ha - 3.08 ha for males and 1.94 ha - 6.18 ha for females. Whereas the start of their daily activity did not correlate with sunset, the end of activity was associated with sunrise. The females never switched their nesting sites, but the males used 7 -10 nesting sites. Nesting sites were located between boulders and inside deadwood piles. Deadwood is an important habitat for insects which serve as food for Garden Dormice (and other small mammals). To this species in its natural habitat it is necessary to sustain deadwood in forests.

An Improved Variable Kernel Density Estimator Based on L2 Regularization

The nature of the kernel density estimator (KDE) is to find the underlying probability density function (p.d.f) for a given dataset. The key to training the KDE is to determine the optimal bandwidth or Parzen window. All the data points share a fixed bandwidth (scalar for univariate KDE and vector for multivariate KDE) in the fixed KDE (FKDE). In this paper, we propose an improved variable KDE (IVKDE) which determines the optimal bandwidth for each data point in the given dataset based on the integrated squared error (ISE) criterion with the L2 regularization term. An effective optimization algorithm is developed to solve the improved objective function. We compare the estimation performance of IVKDE with FKDE and VKDE based on ISE criterion without L2 regularization on four univariate and four multivariate probability distributions. The experimental results show that IVKDE obtains lower estimation errors and thus demonstrate the effectiveness of IVKDE.

Size of home range of Tengmalm’s owl (Aegolius funereus) males during breeding season assessed by radio-telemetry in the Jizera Mountains, Czechia

Abstract Animal home ranges are typically characterized by their size, shape and a given time interval and can be affected by many different biotic and abiotic factors. Understanding of animal movements and assessing the size of their home ranges are essential topics in ecology and necessary for effective species protection, especially concerning birds of prey. Using radio-telemetry (VHF; 2.1 g tail-mounted tags) we studied the movements of two Tengmalm’s owl (Aegolius funereus) males during the breeding season 2008 in a mountain area of Central Europe (the Czech Republic, the Jizera Mountains: 50˚ 50’ N, 15˚ 16’ E). We determined their average nocturnal hunting and diurnal roosting home range sizes. The mean hunting home range size calculated according to the 90% fixed kernel density estimator was 251.1 ± 43.2 ha (± SD). The mean roosting home range size calculated according to the 100% minimum convex polygon method was 57.9 ± 15.8 ha (± SD). The sizes of hunting home ranges during breeding in this study coincide with those previously reported by other studies focusing on Tengmalm’s owl males. However, we found the roosting home ranges were smaller in size compared to those previously reported. This result was most probably connected with different habitat structure in our study area, which was severally damaged by air-pollution in the past, thus probably offering fewer suitable hiding-places, for instance from predators. We found the roosting locations were concentrated in the oldest and densest Norway spruce forest patches. We emphasize that these parts of forest stands require the highest possible protection in our study area.

Home range size of Tengmalm's owl during breeding in Central Europe is determined by prey abundance.

Animal home ranges typically characterized by their size, shape and a given time interval can be affected by many different biotic and abiotic factors. However, despite the fact that many studies have addressed home ranges, our knowledge of the factors influencing the size of area occupied by different animals is, in many cases, still quite poor, especially among raptors. Using radio-telemetry (VHF; 2.1 g tail-mounted tags) we studied movements of 20 Tengmalm’s owl (Aegolius funereus) males during the breeding season in a mountain area of Central Europe (the Czech Republic, the Ore Mountains: 50° 40’ N, 13° 35’ E) between years 2006–2010, determined their average hunting home range size and explored what factors affected the size of home range utilised. The mean breeding home range size calculated according to 95% fixed kernel density estimator was 190.7 ± 65.7 ha (± SD) with a median value of 187.1 ha. Home range size was affected by prey abundance, presence or absence of polygyny, the number of fledglings, and weather conditions. Home range size increased with decreasing prey abundance. Polygynously mated males had overall larger home range than those mated monogamously, and individuals with more fledged young possessed larger home range compared to those with fewer raised fledglings. Finally, we found that home ranges recorded during harsh weather (nights with strong wind speed and/or heavy rain) were smaller in size than those registered during better weather. Overall, the results provide novel insights into what factors may influence home range size and emphasize the prey abundance as a key factor for breeding dynamics in Tengmalm’s owl.

English

The African elephant (Loxodonta africana) require vast areas to meet their survival needs such as food, mates, water, resting sites, and look up positions; the area referred to as home range. We collared 9 bull and 3 female elephants using satellite-linked Geographic Positioning System (GPS) collars in February 2013. Their movements were monitored up to April 2016 in the wider Amboseli landscape. We estimated their home ranges using 100% minimum convex polygon (MCP) and 95% Fixed Kernel Density Estimator (KDE) methods. A total of 48,852 GPS points were used representing 77% of the expected GPS points. This study revealed that bulls had a larger total home range size (MCP = 32,110 km²; KDE = 3,170 km² compared to females (MCP = 10,515 km²; KDE = 3,070 km²). The 95% confidence interval of the monthly range (95% KDE) for all elephants was 6,130 to 7,025 km² with the minimum and maximum range being 5,200 and 7,790 km² respectively. Females had smaller home ranges during the dry and wet season (MCP: dry = 2,974 km²; wet = 1,828 km²; KDE: dry = 2,810 km²; wet = 3,070 km²) than bulls (MCP: dry = 3,312 km²; wet = 13,288 km²; KDE: dry = 2,960 km²; wet = 3,720 km²). The variations of the elephant home range could have been influenced by an interaction of factors including rainfall, human disturbances and land use (e.g., farms, settlements, road network, and fences), water availability, bush cover, food availability, and tracking period. The most important areas that had key habitats for elephants were scattered throughout the Kenya/Tanzania borderland. The Amboseli-Tsavo-Magadi-Natron-West Kilimanjaro elephant population roams within specific areas of the landscape. Trans-boundary efforts should be enhanced to ensure sound management of the elephant-habitat-people interface for continued well-being of the elephant population. Key words: Amboseli ecosystem, elephant, home range, minimum convex polygon, Kenya/Tanzania borderland, kernel density estimator.

Does Plan B work? Home range estimations from stored on board and transmitted data sets produced by GPS-telemetry in the Colombian Amazon.

Telemetry based on Global Positioning Systems (GPS) makes possible to gather large quantities of information in a very fine scale and work with species that were impossible to study in the past. When working with GPS telemetry, the option of storing data on board could be more desirable than the sole satellite transmitted data, due to the increase in the amount of locations available for analysis. Nonetheless, the uncertainty in the retrieving of the collar unit makes satellite-transmitted technologies something to take into account. Therefore, differences between store-on-board (SoB) and satellite-transmitted (IT) data sets need to be considered. Differences between SoB and IT data collected from two lowland tapirs (Tapirus terrestris), were explored by means of the calculation of home range areas by three different methods: the Minimum Convex Polygon (MCP), the Fixed Kernel Density Estimator (KDE) and the Brownian Bridges (BB). Results showed that SoB and IT data sets for the same individual were similar, with fix ranging from 63 % to 85 % respectively, and 16 m to 17 m horizontal errors. Depending on the total number of locations available for each individual, the home ranges estimated showed differences between 2.7 % and 79.3 %, for the 50 % probability contour and between 9.9 % and 61.8 % for the 95 % probability contour. These differences imply variations in the spatial coincidence of the estimated home ranges. We concluded that the use of IT data is not a good option for the estimation of home range areas if the collar settings have not been designed specifically for this use. Nonetheless, geographical representations of the IT based estimators could be of great help to identify areas of use, besides its assistance to locate the collar for its retrieval at the end of the field season and as a proximate backup when collars disappear.

Spatial organization of the pale fox in the Termit Massif of east Niger

Abstract Pale foxes ( Vulpes pallida ) have a widespread distribution across the Saharan-Sahel in northern Africa, but little is known about their ecology and natural history. Here, we provide the 1st ecological information on the species. We captured and radio-collared 10 pale foxes in the Termit & Tin Toumma National Nature and Cultural Reserve of east Niger. The adult body mass (1.20 ± SD 0.18kg, n = 6) was about half of what was previously reported, confirming this species as one of the smallest canids in the world. Body measurements were relatively similar between sexes, suggesting little if any sexual dimorphism. Mean ± SD home range size ( n = 6) was 6.79±3.58 km 2 using 100% minimum convex polygon and 5.62±3.11 km 2 using 95% fixed kernel density estimator. Overlap between adjacent pale fox ranges was generally low (mean overlap index = 0.11±0.22), with nearly exclusive core areas (mean overlap index = 0.02±0.06), suggesting pale foxes are territorial. Overall, the spatial ecology of pale foxes showed similar characteristics to other Vulpes species, especially those inhabiting arid and semiarid environments.

Demographic characteristics, seasonal range and habitat topography of Balkan chamois population in its southernmost limit of its distribution (Giona mountain, Greece)

The annual range of Balkan chamois (Rupicapra rupicapra balcanica) in Giona mountain was found to be 5502 ha, with a low population density (2 individuals/100 ha). Seasonal range patterns varied significantly, with a minimum extent in summer and a maximum in winter (30% and 79% of the annual range, respectively). Summer stress and the rutting period might be associated with the observed aggregated distributions during the summer and autumn (core areas of 28% and 22% of seasonal ranges, respectively, defined after the Fixed Kernel Density Estimator). Chamois were found to use significantly lower altitude habitats in winter (1212 m) than in summer (2223 m), and significantly steeper slopes in winter (35°); aspect was not found to have a significant effect on habitat use. Population structure consisted of kids (21%), yearlings (8%), females (35%) and males (36%). Conservation management for the species should consider poaching, livestock competition and global warming.

Landscape characteristics derived from satellite-tracking data of wintering habitats used by oriental honey buzzards in Borneo

Knowledge of the spatial distribution of the wintering habitats of migratory raptors is a prerequisite to understanding their wintering ecology and managing their habitats. Oriental honey buzzards (OHBs, Pernis ptilorhynchus) are migratory raptors with wintering grounds in Indonesia. OHBs’ wintering habitats can be divided into core and edge habitats with unique landscape characteristics, which influence wintering-site selection. Twenty-three satellite-tracked OHBs (2006–2010) used Borneo as their wintering grounds. The primary aim of this study was to analyze OHBs’ wintering habitat distributions (core and edge habitats) in Borneo and their landscape characteristics in the province of South Kalimantan. Fixed-kernel density estimation was used to estimate the edge and core habitats of 23 OHBs in Borneo. We used a 95 % fixed kernel (FK_95 %) and a 50 % fixed kernel (FK_50 %) to estimate the spatial distribution of edge and core habitats, respectively. Factor analysis was used to analyze landscape characteristics of core and edge habitats. Results showed that edge and core habitats covered about 153,463.4 km2 (20.7 %) and 27,528.3 km2 (3.7 %) of the Borneo area, respectively. Habitat selection by OHBs at wintering sites in both core and edge habitats was highly influenced by the availability of thermal winds and food. However, the more frequent presence of OHBs in core habitats indicates that habitat selection is basically influenced by increased thermal winds associated with particular landform characteristics. Identification of these landscape characteristics provides useful baseline information for ecological-based development, particularly for landscape management and biodiversity conservation.

Home ranges of East Pacific green turtles Chelonia mydas in a highly urbanized temperate foraging ground

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 461:211-221 (2012) - DOI: https://doi.org/10.3354/meps09820 Home ranges of East Pacific green turtles Chelonia mydas in a highly urbanized temperate foraging ground Bradley D. MacDonald1,2,*, Rebecca L. Lewison1, Sheila V. Madrak1, Jeffrey A. Seminoff2, Tomoharu Eguchi2 1Department of Biology, San Diego State University, 5500 Campanile Dr., San Diego, California 92182, USA 2Protected Resources Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 8901 La Jolla Shores Dr., La Jolla, California 92037, USA *Email: brad.macdonald@noaa.gov ABSTRACT: Green sea turtles Chelonia mydas use coastal areas as foraging grounds for the majority of their lives. Human development of coastlines is increasing, but the effects of urban development of foraging grounds on green turtles are poorly understood. We used acoustic telemetry to determine home ranges of green turtles during 2009 to 2011 in San Diego Bay, California, USA, which is a highly urbanized temperate foraging area. Adult and juvenile turtles (n = 25, straight carapace length = 54.9 to 102.5 cm) were tracked for up to 370 d. Based on the fixed kernel densities of 15 turtles, we found individual home range areas (95% utilization distribution) were 2.09 to 8.70 km2 (mean ± SE = 5.51 ± 0.57 km2), where each turtle used 1 or 2 core activity areas (50% utilization distribution). The home ranges of all turtles were exclusively in the southern portion of San Diego Bay, where eelgrass Zostera marina is abundant and where human activity is the lowest within the bay. Core activity areas coincided with eelgrass distribution or occurred adjacent to the warm water-effluent outfall of a power plant. Results from our study suggest that south San Diego Bay serves as important turtle habitat within the bay. Future monitoring is required to document the potential effects of changing environmental conditions, including closure of the power plant, on green turtles residing in San Diego Bay. KEY WORDS: Sea turtle · Urbanized estuary · Power plant · Acoustic telemetry · Fixed kernel density estimator · Conservation Full text in pdf format PreviousNextCite this article as: MacDonald BD, Lewison RL, Madrak SV, Seminoff JA, Eguchi T (2012) Home ranges of East Pacific green turtles Chelonia mydas in a highly urbanized temperate foraging ground. Mar Ecol Prog Ser 461:211-221. https://doi.org/10.3354/meps09820 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 461. Online publication date: August 08, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Evaluating home range techniques: use of Global Positioning System (GPS) collar data from chacma baboons

Global Positioning System (GPS) collars have revolutionized the field of spatial ecology, but to date, few primate studies have used them. We fitted a free-ranging, semi-habituated, juvenile male chacma baboon (Papio hamadryas ursinus) with an automatic self-releasing GPS collar and tracked his movements for 359 days. The collar captured 4254 fixes out of 5719 programmed opportunities, a 74.4 % acquisition rate, suggesting that the collar effectively tracked this baboon in a variety of habitat types. Of the data points captured, 73.7 % were three-dimensional fixes, and of these fixes, 66.9 % were highly accurate, having a dilution of precision of less than four. We calculated home range using three protocols with three estimation methods: minimum convex polygon, fixed kernel-density estimation (KDE), and fixed r local convex hull. Using all data points and the 95 % contour, these methods created home range estimations ranging from 10.8 to 23.1 km(2) for this baboon troop. Our results indicate that the KDE output using all data locations most accurately represented our data set, as it created a continuous home range boundary that excluded unused areas and outlying, potentially exploratory data points while including all seven sleeping sites and a movement corridor. However, home range estimations generated from KDE varied from 15.4 to 18.8 km(2) depending on the smoothing parameter used. Our results demonstrated that the ad hoc smoothing parameter selection technique was a better method for our data set than either the least squares cross-validation or biased cross-validation techniques. Our results demonstrate the need for primatologists to develop a standardized reporting method which documents the tool, screening protocol, and smoothing parameter used in the creation of home range estimations in order to make comparisons that are meaningful.

Inter-nesting habitat-use patterns of loggerhead sea turtles: enhancing satellite tracking with benthic mapping

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 11:77-90 (2010) - DOI: https://doi.org/10.3354/ab00296 Inter-nesting habitat-use patterns of loggerhead sea turtles: enhancing satellite tracking with benthic mapping Kristen M. Hart1,*, David G. Zawada2, Ikuko Fujisaki3, Barbara H. Lidz2 1US Geological Survey, Southeast Ecological Science Center, Davie, Florida 33314, USA 2US Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, Florida 33701, USA 3University of Florida, Ft. Lauderdale Research and Education Center, Davie, Florida 33314, USA *Email: kristen_hart@usgs.gov ABSTRACT: The loggerhead sea turtle Caretta caretta faces declining nest numbers and bycatches from commercial longline fishing in the southeastern USA. Understanding spatial and temporal habitat-use patterns of these turtles, especially reproductive females in the neritic zone, is critical for guiding management decisions. To assess marine turtle habitat use within the Dry Tortugas National Park (DRTO), we used satellite telemetry to identify core-use areas for 7 loggerhead females inter-nesting and tracked in 2008 and 2009. This effort represents the first tracking of DRTO loggerheads, a distinct subpopulation that is 1 of 7 recently proposed for upgrading from threatened to endangered under the US Endangered Species Act. We also used a rapid, high-resolution, digital imaging system to map benthic habitats in turtle core-use areas (i.e. 50% kernel density zones). Loggerhead females were seasonal residents of DRTO for 19 to 51 d, and individual inter-nesting habitats were located within 1.9 km (2008) and 2.3 km (2009) of the nesting beach and tagging site. The core area common to all tagged turtles was 4.2 km2 in size and spanned a depth range of 7.6 to 11.5 m. Mapping results revealed the diversity and distributions of benthic cover available in the core-use area, as well as a heavily used corridor to/from the nesting beach. This combined tagging-mapping approach shows potential for planning and improving the effectiveness of marine protected areas and for developing spatially explicit conservation plans. KEY WORDS: Dry Tortugas · Caretta caretta · Marine protected area · MPA · Marine spatial planning · Satellite telemetry · Benthic cover · Habitat mapping · Fixed-kernel density estimator Full text in pdf format PreviousNextCite this article as: Hart KM, Zawada DG, Fujisaki I, Lidz BH (2010) Inter-nesting habitat-use patterns of loggerhead sea turtles: enhancing satellite tracking with benthic mapping. Aquat Biol 11:77-90. https://doi.org/10.3354/ab00296Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 11, No. 1. Online publication date: November 16, 2010 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2010 Inter-Research.

Home range, core areas and movement in the ‘critically endangered’ kipunji (Rungwecebus kipunji) in southwest Tanzania

AbstractUnderstanding how threatened forest primates use a heterogeneous landscape is essential to ensuring their survival. Kipunji (Rungwecebus kipunji) are ‘critically endangered’, arboreal monkeys restricted to two sites in Tanzania. Over 90% of the population lives in the degraded Rungwe‐Kitulo forests of the Southern Highlands. In this study, we present the first comprehensive investigation into daily path length and home range size of kipunji, based on data from four groups followed simultaneously over 70 consecutive days on Mt. Rungwe. The mean daily distance travelled was 1293 m (SE 150.82), and daily distance was not significantly correlated to group size. Using fixed kernel density estimation, an area enclosing 90% of the home range calculated using the ‘reference’ method as a smoothing parameter, measured a mean of 306.18 ha (SE 67), and the core area (50% use) was 86.55 ha (SE 18.73). Using the ‘least‐squares cross validation’ method, the mean home range and core area were 205.45 ha (SE 57.02) and 55.45 ha (SE 14.23) respectively. Home range overlap was extensive, although contact between groups was rare, with >97.30% of all observations within 20 min separated by >250 m. The data strongly suggest that kipunji are not territorial.

Seasonal movements, home ranges, and territoriality of male swamp rabbits in southeastern Arkansas

Abstract Swamp rabbits (Sylvilagus aquaticus) are of conservation concern throughout portions of its range, and information regarding spatial organization is important for proper species management. Little is known about spacing patterns of swamp rabbits; few studies have directly investigated spatial patterns, particularly related to territoriality. We used radio-telemetry to assess seasonal (dormant, growth, and senescent) home range sizes, seasonal and monthly movements, and territoriality among male swamp rabbits. Mean seasonal home range sizes ranged from 3.8 to 8.4 ha using the 95% fixed kernel density estimator and no differences among seasons were observed. Swamp rabbits moved less during the senescent season than the growth season. Mean seasonal dyad overlap ranged from 7.5 to 13.8%, and no differences were found among seasons. Overlap of all male radio-collared swamp rabbits ranged from 16.7 to 29.8% across seasons. Male swamp rabbits demonstrated non-territoriality during two of the three seasons based on spatial overlap of core use areas. Home range size might not be the best indicator of habitat quality for male swamp rabbits and management efforts aimed at habitat restoration or reintroduction should consider that some swamp rabbits could require more area, even on sites considered to be high quality.

Home ranges of Guiana dolphins (Sotalia guianensis) (Cetacea: Delphinidae) in the Cananéia estuary, Brazil

Home ranges of seven Guiana dolphins (Sotalia guianensis) (Van Bénéden, 1864) were studied in the Cananéia estuary (~25°03′S 47°55′W), south-eastern Brazil. Boat-based observations were conducted from May 2000 to July 2003 in ~132 km2 of protected inner waters. The photo-identification technique was used to follow naturally marked individuals through time and space. From a total of 138 catalogued individuals, five males and two females presented 20+ sightings and were used for home range estimation. Sightings were plotted and analysed in a Geographic Information System (GIS). With the ‘Home Range Tools’ extension the fixed kernel density estimator with band width (smoothing parameter) chosen via least squares cross-validation was performed for each individual. The fixed kernel method was used to estimate the non-parametric utility distribution of each dolphin, keeping band width (h) constant for a data set. The first polygons created by these parameters had an amoeboid shape and in some cases more than one centre of activity. The 95% home range estimated outlines varied from 1.6 to 22.9 km2 (7.9 ± 8.3 km2). This large interval shows strong evidences on individual variation in S. guianensis' home ranges. Several individuals showed small home ranges when compared to other cetacean species. An overlap of home ranges of different sizes and shapes were observed for Guiana dolphins with large range movements. Centres of activity were concentrated in the main entrance of the Cananéia estuary. This was a first attempt to understand the way S. guianensis uses the Cananéia estuary and such data are essential for conservation and management purposes.

Factors Influencing Home-Range Size of Female Florida Black Bears

The manner in which space is utilized by animals is influenced by several factors, including habitat quality and the distribution and abundance of resources. We used 4 years (2000‐2003) of radiotelemetry data to investigate the space-use pattern of female Florida black bears (Ursus americanus floridanus) in the Ocala National Forest and an adjacent residential community of Lynne, north-central Florida. Annual home-range size (95% fixed kernel density estimator) ranged from 3.8 km 2 to 126.9 km 2 , and averaged (6 SE) 24.2 6 3.55 km 2 . Home ranges were largest during 2000 when a drought led to a forest-wide mast failure, suggesting that abundance of food resources can substantially influence space-use pattern. Home-range sizes during autumn (19.92 6 4.59 km 2 ) were substantially larger than during summer (8.26 6 0.99 km 2 ). Although annual home-range size did not differ between the 2 study sites, home ranges in summer were smaller in Lynne (5.30 6 1.01 km 2 ) than in Ocala National Forest (9.82 6 1.29 km 2 ), whereas home ranges in autumn were twice as large in Lynne (35.76 6 13.91 km 2 ) as in Ocala National Forest (13.24 6 1.80 km 2 ). We suggest that site-specific differences in the size of seasonal home range are due to differences in habitat characteristics and the degree of habitat fragmentation between the 2 study sites.

Radio-tracking squirrels: Performance of home range density and linkage estimators with small range and sample size

Studies that use radio-tracking to reveal social structure and habitat use in populations of small and medium-sized mammals face a trade-off between number of location data ( n) and monitoring of many individuals, to maximize efficiency. We simulated these conditions using location data from 30 radio-collared red squirrels, subsampled at different percentages of total number of locations and tested the performance of four home range estimators. Two linkage estimators, the minimum convex polygon (MCP), and the incremental cluster-analysis polygon (ICP) and two probability density estimators, the fixed kernel density estimation with reference smoothing factor (KDE with h ref), and with least squares cross-validation to calculate smoothing factor (KDE LSCV with h lscv). KDE produced the largest home range estimates, MCP and KDE LSCV intermediate estimates, and ICP the smallest ones. Differences between estimators were larger at smaller n, but consistent throughout the entire range of locations (16–74) in our data set. Although KDE is widely used and LSCV is widely recommended to calculate bandwidth, our results confirmed that the value of h has a considerable influence on the home range estimate and varied more strongly when sample size ( n) decreased. Our models showed that overestimation with KDE could be avoided by applying the average ratio of h lscv/ h ref (in our case 0.75) as a multiplier of h ref and use this recalculated bandwidth to produce more reliable home range and core area estimates (KDE adj). MCP and KDE had lower variability than KDE LSCV and ICP. Stability improved with sample size and tended towards an asymptote at more than 60 locations for MCP and KDE. We conclude that high variation in ICP and KDE LSCV at small n limits their applicability to few situations ( n > 70, landscapes with distinct habitat patches where ranges consists of several, separated cores). We recommend use of both MCP and KDE adj for home range size and KDE adj for core area size and propose to estimate a ‘best core area’ based on 85% MCP when a home range is mononuclear and 85% ICP when it is multinuclear.

Home range and seasonal movement of elephants in the Kunene Region, northwestern Namibia

This paper examines the home ranges and seasonal movements of eight GPS-collared elephants (two females and six males) in the northwestern Kunene region of Namibia. Minimum convex polygon (MCP) and the fixed kernel density estimation (FKDE) methods were used to analyse home ranges. The collared elephants showed defined home and seasonal ranges. In the eastern section of the research area, the elephants generally had smaller home ranges that were at their least during the hot and cold dry seasons, expanding during the wet season. In the western areas, the elephants moved between the Hoanib and Hoarusib Rivers in response to available vegetation that did not necessarily correspond to rainfall. The length of movement of collared elephants varied from 54.5 to 473 km in the eastern section of the research area to between 251 to 625 km in the west, over periods of up to five months.

Home range and seasonal movement of elephants in the Kunene Region, northwestern Namibia

This paper examines the home ranges and seasonal movements of eight GPS-collared elephants (two females and six males) in the northwestern Kunene region of Namibia. Minimum convex polygon (MCP) and the fixed kernel density estimation (FKDE) methods were used to analyse home ranges. The collared elephants showed defined home and seasonal ranges. In the eastern section of the research area, the elephants generally had smaller home ranges that were at their least during the hot and cold dry seasons, expanding during the wet season. In the western areas, the elephants moved between the Hoanib and Hoarusib Rivers in response to available vegetation that did not necessarily correspond to rainfall. The length of movement of collared elephants varied from 54.5 to 473 km in the eastern section of the research area to between 251 to 625 km in the west, over periods of up to five months.

Home‐range overlap and spatial organization as indicators for territoriality among male bushbuck ( Tragelaphus scriptus )

Many studies have concluded that territoriality is absent in male bushbuck Tragelaphus scriptus but a minority has suggested that some exclusive mechanisms act between adult males. This study provides indirect evidence for the existence of territorial structures between adult male bushbuck by comparing home-range overlap between adult and sub-adult males. The spatial organization of individuals in relation to each other was established by using numerical classification. Location fixes of 52 males, each individual distinguished by a characteristic coat pattern, were taken over a period of 3 years. Home ranges were estimated using the fixed kernel density estimator. Two indices (coefficient of overlap, index of overlap) were applied to compare home-range overlap between the different male age classes. There was a strong home-range overlap up to the 30% home-range core between sub-adult as well as between adult and sub-adult males, while adult male home ranges overlapped up to the 50% home-range core only. It could be shown that home ranges of adult males overlapped significantly less than those of sub-adult males and those between sub-adult and adult males indicating an exclusive use of central core areas (home sites). Sub-adult males form bachelor pools without being permanently associated. With increasing age, sub-adult males challenge territory holders and replace them in order to take over their exclusive areas. These maturing sub-adult males (young adults), often focused on a particular territory holder denoting the young adults as prospects or candidates.