Home Range Quality Research Articles

Resource dependence analysis of home range quality for pronghorn in south-central New Mexico, USA

Pronghorn (Antilocapra americana) are challenged energetically in arid southwestern North American habitats; hence, identifying habitats that provide for their requirements is important to guide habitat management. We used resource-area-dependence analysis, which relates home range size to composition of home ranges, to determine habitats most associated with decreasing home range sizes (i.e., increasing quality) for pronghorn in south-central New Mexico, USA. Grama grasslands were most associated with home range quality for pronghorn, likely because grama grassland provided more forbs than other habitats, and forbs were the only forage class positively associated with pronghorn diet quality. Grama grassland also provided a diversity of browse, and the low structure facilitates visual detection of threats. Pinyon-juniper woodlands were marginally associated with home range quality of females, again because of relatively high diversity of forbs and browse. Pronghorn could benefit from management that increases diversity and abundance of forbs, such as burning during late-winter or early-spring to favor forbs over grasses and rejuvenate browse; this can also maintain an open canopy in woodlands. While precipitation will always be important for productivity and survival of pronghorn in arid southwestern environments, management that facilitates forbs could allow better forage responses to timely precipitation.

Habitat suitability or female availability? What influences males’ home-range size in a neotropical montane lizard?

In many species, the shape, size, and location of home ranges depend on the spatial positioning of resources. Therefore, evaluating the resources and conditions related to the space use of individuals can provide crucial information on the species’ ecology and sociobiology. In this study, we evaluated factors shaping the use of space by the lizard Tropidurus montanus M.T. Rodrigues, 1987 and assessed how the distribution of resources can affect the size of the home range and how the quality of the male's home range can influence the number of associated females. We hypothesized that ( i) males with a larger body size would have a higher-quality home range, and ( ii) there would be a positive relationship between the home-range size and home-range quality of males and the number of associated females. Our results suggest that males, females, and juveniles adopt different strategies. While females and juveniles have relatively small home ranges located in more suitable locations, males invest in larger home ranges, including in lower-quality habitat patches. Our results suggest that males increase their home ranges to incorporate resources females prefer, enlarging the number of females in their harems.

Having a better home range does not reduce the cost of reproduction in Soay sheep.

A cost of reproduction may not be observable in the presence of environmental or individual heterogeneity because they affect the resources available to individuals. Individual space use is critical in determining both the resources available to individuals and the exposure to factors that mediate the value of these resources (e.g. competition and parasitism). Despite this, there has, to our knowledge, been little research to understand how between-individual differences in resource acquisition, caused by variation in space use, interact with environmental variation occurring at the population scale to influence estimates of the cost of reproduction in natural populations. We used long-term data from the St. Kilda Soay sheep population to understand how differences in age, relative home range quality, and average adult body mass, interacted with annual variation in population density and winter North Atlantic Oscillation index to influence over-winter survival and reproduction in the subsequent year, for females that had invested into reproduction to varying degrees. Our results suggest that Soay sheep females experience costs both in terms of future survival and future reproduction. However, we found little evidence that estimated costs of reproduction vary depending on relative home range quality. There are several possible causes for the lack of a relationship between relative home range quality and our estimate of the costs experienced by females. These include the potential for a correlation between relative home range quality and reproductive allocation to mask a relationship between home range quality and reproductive costs, as well as the potential for the benefit of higher quality home ranges being offset by higher densities. Nevertheless, our results raise questions regarding the presence or context-dependence of relationships between resource access and the estimated cost of reproduction.

Home range size and habitat quality affect breeding success but not parental investment in barn owl males

Life-history theory predicts that parents should balance their limited resources to maximize lifetime fitness, limiting their investment in current reproduction when the fitness value of current progeny is lower than that gained by producing offspring in the future. Here, we examined whether male barn owls (Tyto alba) breeding in low-quality habitats increased their parental effort to successfully complete offspring rearing or limited their investment by paying a fitness cost while saving energy for the future. We equipped 128 males with GPS devices between 2016 and 2020 to collect information on home range size, habitat composition, food provisioning rate to the brood and nightly distances covered. We also recorded nestlings’ growth and survival, as well as males’ body mass variation and future reproductive success. Males living in lower-quality habitats exploited bigger home ranges compared to individuals whose nests were settled in prey-rich habitats. They fed their brood less frequently, while covering longer nightly distance, resulting in a slower growth of late-hatched nestlings and ultimately in a lower fledging success. As males did not differ in body mass variation or future reproductive success our findings suggest that males hunting in home ranges with less prey-rich structures do not jeopardize future reproduction by investing disproportionately larger resources to compensate for their current low home range quality.

Resource-area-dependence analysis of desert mule deer habitats in the San Andres Mountains, New Mexico, USA

Desert mule deer (Odocoileus hemionus eremicus) populations throughout the arid Southwestern USA and Mexico have declined; hence, it is important to identify habitats that provide for their requirements to inform habitat management. We used resource-area-dependence analysis (RADA), which relates home range size to composition of home ranges, to determine habitats most associated with decreasing home range sizes (i.e., increasing quality) for adult male and female mule deer in the San Andres Mountains (SAM) of south-central New Mexico, USA. Pinyon-juniper woodland and oak-mountain mahogany shrubland were the habitats most associated with home range quality for both lactating and dry females, likely because they provided the highest quantity and diversity of browse and the best cover attributes of habitat types in the SAM. Grama grassland was the only habitat associated with male home range size; despite the lack of cover, grama grassland provided more forbs than other habitats in the SAM, and males are less tied to cover than females. Management actions that increase diversity and retard successional status of woodlands and shrublands while retaining cover could increase habitat quality for female mule deer. Actions that favor forbs and increase cover in grasslands would similarly increase habitat quality for males.

Morphometric signals of population decline in diademed sifakas occupying degraded rainforest habitat in Madagascar

Anthropogenic habitat change can have varied impacts on primates, including both negative and positive outcomes. Even when behavioural shifts are seen, they may reflect decreased health, or simply behavioural flexibility; understanding this distinction is important for conservation efforts. This study examines habitat-related variation in adult and immature morphometrics among diademed sifakas (Propithecus diadema). We collected morphometric data from sifakas at Tsinjoarivo, Madagascar (19 years, 188 captures, 113 individuals). Captures spanned 12 groups, five within continuous forest (“CONT”), and seven in degraded fragments (“FRAG”) where sifakas have lower nutritional intakes. Few consistent differences were found between CONT and FRAG groups. However, using home range quality as a covariate rather than a CONT/FRAG dichotomy revealed a threshold: the two FRAG groups in the lowest-quality habitat showed low adult mass and condition (wasting), and low immature mass and length (stunting). Though less-disturbed fragments apparently provide viable habitat, we suggest the sifakas in the most challenging habitats cannot evolve fast enough to keep up with such rapid habitat change. We suggest other long-lived organisms will show similar morphometric “warning signs” (wasting in adults, stunting in immatures); selected morphometric variables can thus be useful at gauging vulnerability of populations in the face of anthropogenic change.

Female Soay sheep do not adjust their maternal care behaviour to the quality of their home range

Lay SummaryUngulate mothers should provide more maternal care when resources are plenty. Few studies quantify individual differences in resource use, instead using population-level metrics such as between-year variation in environmental conditions. We found that care provisioning by female Soay sheep was similar, regardless of their home range quality. This may be because summer resource levels are high, and demonstrates the need to accurately characterize the environment experienced by individual animals.Twitter: @ce_regan

Between-group contest competition among tufted capuchin monkeys, Sapajus nigritus, and the role of male resource defence

Between-group contest competition and the relative importance of male resource defence have recently been suggested to have been previously underestimated. When males contribute to the defence of group-controlled resources, the quality of the home range may depend on the resource-holding potential of resident males. Among Argentine tufted capuchin monkeys, resident males defend access to high-quality food resources. Here I investigate consequences of this male–male cooperation for intergroup dominance relationships and home range quality. I recorded ranging behaviour for four habituated groups in Iguazú National Park to identify home ranges and core areas, and measured the availability of food species within botanical plots placed in these areas. I recorded the location and outcome of intergroup encounters and fitted predictive models using generalized estimating equations to assess the relative importance of male group size and location on the outcome, before performing linear mixed-effects modelling to identify long-term benefits of winning encounters. Relative male group size was the most important factor in determining the winner of encounters, outweighing the competitive advantage of ownership. The density of food species within the core area was not affected by the group's competitive ability, but core area size increased with male group size. Moreover, dominant groups were better able to defend their core area, and adjusting for the degree of home range overlap revealed that dominant groups may have higher per capita access to food. These results suggest that male–male cooperation in defence of food resources could ultimately increase female reproductive success. ► I investigated intergroup dominance relationships and home range quality in tufted capuchins. ► Both sexes participated in intergroup aggression, but only male group size affected the outcome. ► There was no evidence of a ‘home field advantage’ favouring small groups near the centre of their home range. ► Large male group size increased home range exclusivity and per capita access to food resources.

Movement paths reveal scale-dependent habitat decisions by Canada lynx

We documented the relative grain at which Canada lynx (Lynx canadensis) perceive habitat heterogeneity using fractal dimension of foraging paths. We evaluated whether lynx expended greater foraging effort (i.e., greater fractal dimension of movement paths) in patches with the highest density of snowshoe hares (Lepus americanus), or in patches with intermediate densities of prey where lower stem densities and greater visibility promote increased mobility and access to prey. Lynx foraged within patches with intermediate to high hare density and intermediate cover for hares, and thus, attempted to maximize access to prey rather than exposure to habitats with highest prey density but optimal escape cover. Fractal dimension of movement paths was greater within preferred than in nonpreferred habitats and corresponded with higher foraging success in preferred habitats. Movement paths were more tortuous at broader than finer scales, suggesting that lynx were exhibiting stronger coarse-grained than fine-grained habitat preferences. Higher fractal dimension of movement paths reduced the number of transitions between patches of higher and lower foraging quality, resulting in individual movement patterns matching the scale of interpatch variation in hare abundance and accessibility within home ranges. Lynx made their strongest foraging decisions when exhibiting higher-order resource selection, so focusing conservation efforts to alter within-patch structure may be less effective than creating patch- and landscape-scale conditions that enhance foraging success. Coarse-grained resource selection by wide-ranging carnivores may reduce the importance of fine-scale conservation efforts and emphasizes the importance of focusing conservation for these coarse-grained species on factors influencing home-range quality and maintenance of viable landscapes. DOI: 10.1644/10-MAMM-A-005.1.

Alternative Strategies of Space use of Female Red Deer in a Mountainous Habitat

Alternative strategies of space use may be present in a species or in a population as a response to different environmental parameters, especially in mountainous habitats, where heavy snowfalls in winter may determine important variations of habitat quality. The spatial behaviour of 20 radiotagged red deer hinds was assessed in a mountainous habitat in the eastern Italian Alps from 2002 to 2004. Two groups of hinds were identified: ‘resident’ females remained in the same area throughout the year; ‘shifter’ females showed separated winter and summer areas. No significant difference was found in seasonal home-range sizes between resident and shifter hinds in 2002 and in 2003. Each year, in summer, home-range quality of shifter hinds was significantly better than that of resident ones, while, in winter home ranges, habitat diversity was similar in the two groups. During the severe winter 2003–2004, 33% of females summering in lower quality habitat died, whereas mild winters did not influence the survival of our collared hinds.

Shallow‐water habitats as sources of fallback foods for hominins

Underground storage organs (USOs) have been proposed as critical fallback foods for early hominins in savanna, but there has been little discussion as to which habitats would have been important sources of USOs. USOs consumed by hominins could have included both underwater and underground storage organs, i.e., from both aquatic and terrestrial habitats. Shallow aquatic habitats tend to offer high plant growth rates, high USO densities, and relatively continuous USO availability throughout the year. Baboons in the Okavango delta use aquatic USOs as a fallback food, and aquatic or semiaquatic USOs support high-density human populations in various parts of the world. As expected given fossilization requisites, the African early- to mid-Pleistocene shows an association of Homo and Paranthropus fossils with shallow-water and flooded habitats where high densities of plant-bearing USOs are likely to have occurred. Given that early hominins in the tropics lived in relatively dry habitats, while others occupied temperate latitudes, ripe, fleshy fruits of the type preferred by African apes would not normally have been available year round. We therefore suggest that water-associated USOs were likely to have been key fallback foods, and that dry-season access to aquatic habitats would have been an important predictor of hominin home range quality. This study differs from traditional savanna chimpanzee models of hominin origins by proposing that access to aquatic habitats was a necessary condition for adaptation to savanna habitats. It also raises the possibility that harvesting efficiency in shallow water promoted adaptations for habitual bipedality in early hominins.

Varying Ecological Quality Influences the Probability of Polyandry in White‐handed Gibbons (Hylobates lar) in Thailand

ABSTRACTAlthough members of the family Hylobatidae are known to be monogamous, adult white‐handed gibbons (Hylobates lar) at Khao Yai National Park, Thailand, also show multimale groups and polyandry. A need for more than one male to successfully raise offspring cannot explain the occurrence of polyandry in these territorial primates, because direct paternal care is absent in this species. We hypothesize that polyandry is primarily related to costs/benefits for males of cooperatively defending a female and/or resources; our prediction was that polyandry would become more frequent with increasing costs of female/resource defense. We measured the ecological quality of seven gibbon home ranges over a 3‐yr period (2001–2003) to investigate how resource availability affected the probability of polyandry, and found a significant negative relationship between home range quality and home range size. Larger home ranges were of lower quality. As predicted, groups living on larger, poorer home ranges also experienced longer periods of polyandry. In forest areas of comparatively low quality, acquiring and maintaining a large home range that includes enough resources for a female to reproduce steadily may surpass a single male's capacity. Our model of cooperative male polyandry was supported by preliminary data of shared territorial defense and access to the female. However, interaction proportions were strongly skewed, and female's primary male partners monopolized grooming and mating. Nevertheless, a primary male on a large territory may benefit from the presence of a secondary male with aid in territorial/female defense, whereas a secondary male may gain by avoiding high dispersal costs.

Test of the ecological‐constraints model on ursine colobus monkeys (Colobus vellerosus) in Ghana

For group-living mammals, the ecological-constraints model predicts that within-group feeding competition will increase as group size increases, necessitating more daily travel to find food and thereby constraining group size. It provides a useful tool for detecting scramble competition any time it is difficult to determine whether or not food is limiting. We tested the ecological-constraints model on highly folivorous ursine colobus monkeys (Colobus vellerosus) at the Boabeng-Fiema Monkey Sanctuary in Ghana. Three differently sized groups were followed for 13 months and two others were followed for 6 months each in 2004-2005 using focal-animal sampling and ranging scans; ecological plots and phenology surveys were used to determine home-range quality and food availability. There was relatively little difference in home-range quality, monthly food availability, diet, adult female ingestion rates, and rate of travel within food patches between the groups. However, home-range size, day-range length, and percent of time spent feeding all increased with group size. We performed a single large test of the ecological-constraints model by combining several separate Spearman correlations, each testing different predictions under the model, using Fisher's log-likelihood method. It showed that the ecological-constraints model was supported in this study; scramble competition in this population is manifesting in increased ranging and time spent feeding. How costly this increased energy expenditure is for individuals in larger groups remains to be determined.

LIFETIME REPRODUCTIVE SUCCESS AND COMPOSITION OF THE HOME RANGE IN A LARGE HERBIVORE

The relationship between individual performance and nonrandom use of habitat is fundamental to ecology; however, empirical tests of this relationship remain limited, especially for higher orders of selection like that of the home range. We quantified the association between lifetime reproductive success (LRS) and variables describing lifetime home ranges during the period of maternal care (spring to autumn) for 77 female roe deer (Capreolus capreolus) at Trois-Fontaines, Champagne-Ardenne, France (1976-2000). We maintained population growth rate (adjusted to account for removals of non-focal animals) near rmax, which enabled us to define the fitness-habitat relationship in the absence of density effects. Using a negative binomial model, we showed that a roe deer's incorporation into its home range of habitat components important to food, cover, and edge (meadows, thickets, and increased density of road allowances) was significantly related to LRS. Further, LRS decreased with increasing age of naturally reclaimed meadows at the time of a deer's birth, which may have reflected a cohort effect related to, but not entirely explained by, a decline in quality of meadows through time. Predictive capacity of the selected model, estimated as the median correlation (rs) between predicted and observed LRS among deer of cross-validation samples, was 0.55. The strength of this relationship suggests that processes like selection of the site of a home range during dispersal may play a more important role in determining fitness of individuals than previously thought. Individual fitness of highly sedentary income breeders with high reproductive output such as roe deer should be more dependent on home range quality during the period of maternal care compared to capital breeders with low reproductive output. Identification of the most important habitat attributes to survival and reproduction at low density (low levels of intraspecific competition) may prove useful for defining habitat value ("intrinsic habitat value").

Are female tree agamas (Acanthocercus atricollis atricollis) turned on by males or resources?

We examined the relative importance of male and home range quality on female-male spatial overlap in the tree agama, Acanthocercus atricollis atricollis. Specifically, we asked whether males in good condition had the greatest spatial overlap with females, whether these same males have the best home ranges, or whether females are simply occupying areas with the best habitat and highest food abundance. Tree structure and prey abundance were used as measures of male home range quality, and male snout-vent length and male body condition were used as indices of male quality. Males had significantly larger home ranges compared to females and female-male overlap was common, while male-male overlap was marginal in a few cases (n = 3). Contrary to prediction, larger males did not occupy larger areas and home range size was not influenced by prey abundance. However, there was significant variation in prey availability between male areas. Female-male overlap was linked to prey abundance in male home ranges, possibly because of the direct influence it has on female fitness. However, several high quality males with high spatial overlap with females also had relatively high prey abundance. Male quality may well be linked to resource availability, but small sample size requires a cautionary interpretation.

Resource heterogeneity affects demography of the Costa Rican ant Aphaenogaster araneoides

How do animals respond to an unpredictably heterogeneous environment? Ants foraging in the leaf litter of tropical wet forests experience unpredictably fluctuating food resources. To study how an ant species responds to these changes, foragers were tracked to determine home ranges of 51 colonies of Aphaenogaster araneoides, in three sites in a Costa Rican tropical wet forest. Of these colonies 16 were excavated to measure colony size, colony growth, and reproductive investment. These demographic variables were compared with two measures of home range quality: leaf litter dry weight and mass of arthropods. Home range areas of colonies were highly correlated with colony size, and moderately correlated with resource abundance. Colony growth was independent of colony size, as is found in other ants in unpredictable environments. The growth of colonies was closely associated with resource abundance. Production of the male reproductive caste was closely tied to the size of a colony rather than growth, but male production in slow-growing colonies was limited. Colonies foraging within high-quality environments grew at a faster rate, but reproduction was mainly correlated with colony size. Furthermore, it was found that the frequency of foragers in long-term treatment plots with supplemental food and reduced leaf-litter quality was not significantly different from the frequency of foragers in control plots. This rain-forest ant does not modify its home range areas in response to poor environments, and as a result, small-scale environmental heterogeneity strongly determines growth and reproduction.

Tests for cooperative behaviour between stallions

Breeding groups with multiple stallions occur sympatrically with single-stallion breeding groups in feral horse, Equus caballus, populations. Mutualism and reciprocal altruism between stallions have been proposed to explain the origin and functioning of multistallion bands. However, empirical support for these hypotheses is contradictory and incomplete. Furthermore, there are no explicit tests of the predictions that each hypothesis makes about stallion behaviour and social structure. We compared nine multistallion and 18 single-stallion bands in the Kaimanawa Ranges, New Zealand. Compared with agonistic behaviours, affiliative behaviours were relatively unimportant in the relationships between stallions within bands. The number of stallions in the band did not have a positive influence on mare group size, stability, home range quality or reproductive success in bands. Furthermore, there was a positive relationship between aggression (‘intolerance’) by the dominant towards subordinate stallions and the subordinates' effort in mare group defence (‘helping’) but a negative relationship between helping effort by subordinates and their proximity to, and mating with, the bands' mares. Therefore, the predictions of the mutualism and reciprocal altruism hypotheses were not supported. Indeed, for some of the predictions we found the opposite outcomes to be true. Multistallion bands had significantly poorer reproductive success, and dominant stallions were less tolerant of subordinates that helped most and reduced their access to mares. Nevertheless, in all other respects Kaimanawa stallions in multistallion bands behaved like those described elsewhere. Thus, we reject cooperative hypotheses for multimale breeding groups in horses and discuss the mate parasitism and consort hypotheses as better alternatives.

Home-range ecology, aggressive behaviour, and survival in juvenile lizards, Psammodromus algirus

Individual animals are assumed to gain possession of areas where they win fights or chases, while those that lose agonistic interactions leave areas where they were defeated. Thus, the more dominant animal secures the territory, often excluding subordinates from optimal habitat. This assumption forms the basis for concluding that the degree of aggressiveness or relative dominance of an individual may be important in determining the size or quality of a territory that it can secure. I examined in the field the relationships between home-range size, quality of home range, and degree of aggressiveness and their effects on survivorship in juvenile male lizards (Psammodromus algirus). The degree of aggressiveness was determined using tethered intruders presented to resident individuals in the field. The more aggressive individuals had larger home ranges than the less aggressive ones. Furthermore, home-range size and vegetative cover in the home range also influenced the probability of survival: survivors had larger home ranges, with a greater amount of vegetative cover, than nonsurvivors.

Egg Size and Annual Egg Production by Female Desert Tortoises (Gopherus agassizii): The Importance of Food Abundance, Body Size, and Date of Egg Shelling

We studied egg production in two Californian populations of desert tortoises, (Gopherus agassizii) in 1992 and 1993. One population inhabited the Desert Tortoise Research Natural Area (DTNA) in the western Mojave Desert, where most of the rain falls in the winter. The second population lived near Goffs, in the eastern Mojave, where annual precipitation is divided more evenly between winter and sum- mer. Due to El Niio conditions, heavy winter rains fell at both sites in both years (1991-1992 and 1992- 1993). Consequently, the biomass of spring annuals and annual egg production by tortoises were high in both years at both sites. There were no differences in reproductive output between years so we pooled data for both years to examine the relationship between egg-laying parameters (clutch size and frequency, annual egg production, egg size, etc.) and female size. Variation in annual egg production was due mainly to variation in clutch size, not clutch frequency. Annual egg production per female was lower at DTNA than at Goffs, because some adult females at DTNA did not produce eggs in some years. Females that did lay eggs produced the same number of eggs per year at both sites, even though females at Goffs were smaller (midline carapace length = 214 mm) than females at DTNA (MCL = 234 mm). Despite correction for these body size differences, the eggs produced at Goffs were smaller in all dimensions than eggs produced at DTNA. Smaller eggs and presumably smaller neonates may be related to the greater predictability of sum- mer rain and consequent greater food supply for emergent hatchlings at Goffs. For adult females, food supply probably limits reproduction only during drought years. How can individual females vary their annual reproductive output? Our more extensive data for DTNA tortoises showed that larger females pro- duced larger clutch sizes. In addition, by statistically removing the effects of body size we showed that larger clutches contained smaller eggs. Moreover, larger females produced eggs earlier in the year giving them a better opportunity to produce a second clutch that year. Thus, timing of first clutch was important Still, much of the variation in reproductive output was not explained. Other characteristics of individuals (e.g, age, genetics, physiological maturity, home range quality, or forage selection) may explain some of the variation in reproductive output

Topographical constraints and home range quality

The topography of an area affects the animals that live in at. Using digitized topographic maps of our mountainous study area in North Carolina. USA, and using radio telemetry data for locations of black bears Ursus americanus, we tested the hypotheses that topography influences home ranges of black bears and that topography affects access to resources by black bears. Use of space by bears correlated positively with steepness of slope but negatively with relative elevation. The perimeters of bears” home ranges aligned with ridges and valleys more than expected by chance and home ranges were oriented on major topographic features, such as watersheds and basins. Bears’ homo ranges had lower resource values than was optimal for their home range locations and access to resources was limited by topography'. Ignoring topography may lead researchers to misunderstand the ecology and behavior of animals that live in mountainous areas.