Dynamic spatial partitioning and coexistence among tall grass grazers in an African savanna

Competitive relationships among mobile animals may be expressed through dynamically changing spatial relationships over different time frames. Less common species that are apparently inferior competitors may be able to coexist with more abundant species by concentrating in regions of the landscape little utilized by the former at spatio‐temporal scales from annual or seasonal ranges to the specific foraging localities exploited at different stages of the annual cycle. Spatial relationships may be influenced further by dependencies on other resources, predation risks and facilitatory interactions under certain conditions. Our study aimed to determine whether competition with more abundant zebra and buffalo restricted the abundance of sable antelope in a region where these three tall‐grass grazers overlapped in their herd distributions. We tracked the simultaneous movements of animals representing herds of these species over two dry seasons and one wet season using GPS‐GSM collars, and estimated seasonal or monthly range extents and their overlap. We also compared daily separation distances between these animals against the null pattern expected if their movements had been independent, and assessed how prior grazing by buffalo influenced the subsequent use of these localities by sable. The range of the sable herd was mostly separated from the seasonal range of the buffalo herd during the late dry season of 2006 and throughout the dry season of 2007. Seasonal home ranges of zebra herds overlapped partially with the range of the sable herd during most of the year. Even during times when their ranges overlapped, sable were rarely recorded within <1 km of the buffalo herd. Prior grazing by buffalo beyond a threshold level inhibited later use of these localities by sable, but the sable were nevertheless able to exploit places that were little utilized by buffalo at that time. Sable were less able to evade overlap with the small, mobile zebra herds, and hence more vulnerable to competitive exclusion by zebra than by buffalo. Our findings demonstrate how less abundant species can restrict competition from more abundant competitors through dynamic spatial partitioning in regions where their home ranges overlap.     

The origins of Iberian horses assessed via mitochondrial DNA

Despite a number of recent studies that have focused on the origin of domestic horses, genetic relationships between major geographical clusters still remain poorly understood. In this study we analyzed a 296 bp mtDNA fragment from the HVI region of 171 horses representing 11 native Iberian, Barb, and Exmoor breeds to assess the maternal phylogeography of Iberian horses. The mtDNA haplogroup with a CCG motif (nucleotide position 15,494 to 15,496) was the most frequent in Iberian and Barb breeds (0.42 and 0.57, respectively), regardless of geographic location or group of breeds. This finding supports the close genetic relationship between the ancestral mare populations of the Iberian Peninsula and Northern Africa. Phenotypic differences among the Northern and Southern Iberian groups of breeds are not explained by population subdivision based on maternal lineages. Our results also suggest that Northern Iberian ponies--which are phenotypically close to British ponies, especially Exmoor--are the result of an introgression rather than population replacement.     

Seasonal home ranges of elephants (Loxodonta africana) and their movements between Sabi Sand Reserve and Kruger National Park

We studied the seasonal home ranges and space use of three breeding herds of elephants (Loxodonta africana) for 3–5 years in an area comprising South Africa’s Sabi Sand Reserve (SSR) and Kruger National Park (KNP). Global Positioning System (GPS) transmitters were attached to the matriarchs of three herds and set to transmit a single daily location. Each herd was located in SSR 31%, 60% and 84% of the time. During the wet summer months, the herds walked longer distances and occupied larger seasonal home ranges than during the corresponding dry winter period. Core areas were centred on riverine habitats within both parks, with all three herds exhibiting closer distances to rivers and artificial water holes than would be expected if they were moving randomly. Home ranges within SSR overlapped much of the park. However, in KNP they occupied discrete areas with little overlap. Much of the movement between the two parks occurred along well‐defined corridors. This study shows that elephant herds depended upon the resources of both parks, providing an insight into their within‐ and between‐seasonal movements. This highlights the importance of ongoing co‐operation between wildlife managers from both parks when forming policy.     

Preliminary investigation of morphological differences between ten breeds of horses suggests selection for paedomorphosis

Paedomorphosis is the retention of juvenile morphology at maturity and is important in generating evolutionary change in domestic species and species in the wild. When comparing dogs with the wolf, this preliminary study saw paedomorphosis in their physical and behavioral traits (Goodwin, Bradshaw, & Wickens, 1997). This preliminary study compared morphological characteristics of 10 breeds from northern regions (Shetland ponies) and southern regions (Arabians) with the Exmoor pony. Twenty-three respondents from the United Kingdom and Australia rated the breeds for 7 physical traits. As evidenced by low standard deviations, the respondents demonstrated a high degree of agreement. The study ranked breeds from the most similar (Highland pony) to the least similar (Arabian) to the Exmoor pony. The least similar breeds had physical traits suggestive of paedomorphosis: small heads, long legs, and a low head-to-body ratio. This preliminary study suggests that morphological, behavioral, and physiological differences between the breeds-plus morphometric comparisons of extant breeds and faunal remains of predomestication horses-warrant further study.     

Home range size, spatial distribution and habitat use of elephants in two enclosed game reserves in the Eastern Cape Province, South Africa

We studied space use and habitat selection by elephants in two enclosed reserves in the Eastern Cape Province (South Africa) that conserve components of the regionally important and poorly conserved Thicket Biome. Home ranges of bulls and herds occupied most of the reserves, and core areas were significantly smaller and centred on permanent water. There was no significant difference in home range size of bulls and herds and both were significantly smaller in winter than summer. Components of the Thicket Biome occurred in the home ranges and core areas of all elephants where it was either used according to its abundance or avoided. However, this should not be interpreted as indicating that elephants will not affect plants of the Thicket Biome since change will be cumulative and monitoring should be ongoing to ensure the conservation of this regionally important Biome.     

The feral goats of Kielderhead Moor

Herds of feral goats are present along the high ground of the Scottish Borders at the College, Hindhope, Kielderhead Moor (the study area), Bewcastle Fell and Roan Fell.
In the study area the nannies remained solitary, or in the company of their yearlings on the steep ground below the high moor throughout the winter. After the birth of their kids in March two female herds were formed each with a herd billy which came from the two male herds which were present through the winter on the high moor. The male herds left the study area in the spring and their ranges are not known. The two female herds maintained separate ranges on the high moor until the end of August when they combined into one large herd and were joined by a strange herd of billies which had not previously been seen.
After the first three or four days of its life the kid is left in a hiding place for most of the day whilst its mother ranges widely grazing with the herd. The kids join the herd when they are about six weeks old.
The Kielderhead Moor goats had a recruitment rate of 0–29/nanny/year and the females have a further expectation of life of 3–7 years. Figures for the billies are unreliable as disappearances of males from the moor are more likely to be the result of emigration than of deaths. While the herds of nannies have fairly restricted home ranges there is some evidence to suggest that many of the billies wander freely along the Borders.
In the early part of the summer the sheep and goats are eating very similar proportions of the plants present on the moor. Later on in the season there is a divergence with the sheep eating less Calluna while the goats eat less Eriophorum , but as the Trichophorum becomes available both animals include this in their diet.     

Home range occupation and habitat use of sable antelope in the Okavango Delta region of northern Botswana

Animals selectively utilize their environments within a hierarchical framework. Our study addressed how the home ranges of sable antelope selectively incorporated the landscape and habitat types available to them. It was conducted in a region of northern Botswana where the sable population was expected to be thriving, in contrast to their threatened status in the wild in South Africa. The movements and habitat use of three neighbouring sable herds were recorded by global positioning system (GPS) telemetry during parts of the seasonal cycle in a region adjoining the seasonally flooded Okavango Delta. Total home range extents covered by these herds were larger than those found for sable in other areas, and local population densities, taking into account the herd sizes, were accordingly lower than in these other areas. Access to surface water appeared to be the main limitation on seasonal home range occupation. Almost all of the local vegetation types were utilized, but sable herds generally favoured dryland grassland during the dry season and floodplain grassland during the wet season, contrary to what we had expected. Hence, it appeared that local home range occupation and habitat use by the three sable antelope herds could be influenced more by interactions with potential competitors and predators than by intrinsic habitat suitability.     

Observations on a small group of mountain gorillas (Gorilla gorilla beringei).

On the basis of a 5-month field study, data are presented on home range, patterns of daily movement and social behaviour in a small free-living gorilla group. Changes in group composition that occurred during the study are analysed with special reference to their effect on inter-individual distance. The relationships with other groups and lone individuals whose home ranges overlapped with that of the group studied are examined on the basis of intergroup contacts.     

Permeability of Neotropical agricultural lands to a key native ungulate—Are well‐connected forests important?

Much of what remains of the Earth's tropical forests is embedded within agricultural landscapes, where forest is reduced and fragmented. As native forest ungulates are critical to maintaining forest function, it is imperative to understand how this functional group responds to declines in forest cover and connectivity resulting from agricultural expansion. We addressed this issue by evaluating selection of forest cover and forest connectivity by a key native ungulate of Neotropical forests, the white‐lipped peccary (Tayassu pecari Link 1795, Tayassuidae, Cetartiodactyla), in agricultural landscapes of Brazil. We evaluated selection using compositional analysis at two hierarchical levels, landscape, and home range. From 2013 to 2019, we GPS‐tracked eight white‐lipped peccary herds in Southwest Brazil, resulting in a total of 14,460 GPS locations. We found that herds can live in landscapes with a wide range of forest cover (35%–81% of home ranges covered by native forest), with significant, but not strong, selection at the landscape level (p = .045). Nevertheless, herds strongly select for forest cover within their home ranges (81%–97% of locations within native forest; highly significant selection at the home‐range level: p = .008). As for connectivity, herds significantly select the largest, most connected forest fragments at the landscape level (p = .04), but not at the home‐range level (p = .07). Our results support that Neotropical forests within agricultural landscapes need to be well connected in order to preserve this key native ungulate and maintain long‐term forest function. Abstract in Portuguese is available with online material.     

Combining microsatellite and pedigree data to estimate relationships among Skyros ponies

Relationship coefficients are particularly useful to improve genetic management of endangered populations. These coefficients are traditionally based on pedigree data, but in case of incomplete or inexistent pedigrees they are replaced by coefficients calculated from molecular data. The main objective of this study was to develop a new method to estimate relationship coefficients by combining molecular with pedigree data, which is useful for specific situations where neither pedigree nor molecular data are complete. The developed method was applied to contribute to the conservation of the Skyros pony breed, which consists of less than 200 individuals, divided into 3 main herds or subpopulations. In this study, relationships between individuals were estimated using traditional estimators as well as the newly developed method. For this purpose, 99 Skyros ponies were genotyped at 16 microsatellite loci. It appeared that the limitation of the most common molecular-based estimators is the use of weights that assume relationships equal to 0. The results showed that, as a consequence of this limitation, negative relationship values can be obtained in small inbred populations, for example. By contrast, the combined estimator gave no negative values. Using principal component analysis, the combined estimator also enabled a better graphic differentiation between the 3 subpopulations defined previously. In conclusion, this new estimator can be a promising alternative to traditionally used estimators, especially in inbred populations, with both incomplete pedigree and molecular information.     

A Face in the Crowd: A Non-Invasive and Cost Effective Photo-Identification Methodology to Understand the Fine Scale Movement of Eastern Water Dragons

Ectothermic vertebrates face many challenges of thermoregulation. Many species rely on behavioral thermoregulation and move within their landscape to maintain homeostasis. Understanding the fine-scale nature of this regulation through tracking techniques can provide a better understanding of the relationships between such species and their dynamic environments. The use of animal tracking and telemetry technology has allowed the extensive collection of such data which has enabled us to better understand the ways animals move within their landscape. However, such technologies do not come without certain costs: they are generally invasive, relatively expensive, can be too heavy for small sized animals and unreliable in certain habitats. This study provides a cost-effective and non-invasive method through photo-identification, to determine fine scale movements of individuals. With our methodology, we have been able to find that male eastern water dragons (Intellagama leuseurii) have home ranges one and a half times larger than those of females. Furthermore, we found intraspecific differences in the size of home ranges depending on the time of the day. Lastly, we found that location mostly influenced females’ home ranges, but not males and discuss why this may be so. Overall, we provide valuable information regarding the ecology of the eastern water dragon, but most importantly demonstrate that non-invasive photo-identification can be successfully applied to the study of reptiles.     

Identifying Space Use at Foraging Arena Scale within the Home Ranges of Large Herbivores

An intermediate spatiotemporal scale of food procurement by large herbivores is evident within annual or seasonal home ranges. It takes the form of settlement periods spanning several days or weeks during which foraging activity is confined to spatially discrete foraging arenas, separated by roaming interludes. Extended by areas occupied for other activities, these foraging arenas contribute towards generating the home range structure. We delineated and compared the foraging arenas exploited by two African large herbivores, sable antelope (a ruminant) and plains zebra (a non-ruminant), using GPS-derived movement data. We developed a novel approach to specifically delineate foraging arenas based on local change points in distance relative to adjoining clusters of locations, and compared its output with modifications of two published methods developed for home range estimation and residence time estimation respectively. We compared how these herbivore species responded to seasonal variation in food resources and how they differed in their spatial patterns of resource utilization. Sable antelope herds tended to concentrate their space use locally, while zebra herds moved more opportunistically over a wider set of foraging arenas. The amalgamated extent of the foraging arenas exploited by sable herds amounted to 12-30 km², compared with 22-100 km² for the zebra herds. Half-day displacement distances differed between settlement periods and roaming interludes, and zebra herds generally shifted further over 12h than sable herds. Foraging arenas of sable herds tended to be smaller than those of zebra, and were occupied for period twice as long, and hence exploited more intensively in days spent per unit area than the foraging arenas of zebra. For sable both the intensity of utilization of foraging arenas and proportion of days spent in foraging arenas relative to roaming interludes declined as food resources diminished seasonally, while zebra showed no seasonal variation in these metrics. Identifying patterns of space use at foraging arena scale helps reveal mechanisms generating the home range extent, and in turn the local population density. Thereby it helps forge links between behavioural ecology, movement ecology and population ecology.     

Variation of group size among African buffalo herds in a forest-savanna mosaic landscape

Documenting within species group size variation is important to completely understand social organization within species and to interpret variation among species. Here, I investigated group size of African buffalo Syncerus caffer over 2 years in a heterogeneous landscape. African buffalo use closed continuous forest and vast open savannas, and anecdotal observations suggest that habitat type influences their social structure. While the Cape buffalo Syncerus caffer caffer is well studied, few data exist for the forest-dwelling Syncerus caffer nanus . I observed forest buffalo at Lopé National Park, Gabon, and examined variation of group size. Eighteen forest buffalo herds used the study area with an estimated population of 342 individuals (∼5 buffalo km⁻²). The mean group size for the 18 herds was 12 ± 2 (range of means=3–24), considerably smaller than Cape buffalo herds. For eight radiocollared forest buffalo, the mean group size was stable, varying little with time of day, across seasons, or between savanna and marsh habitat. However, herd size varied widely across herds, from fewer than 10 individuals in the smallest herds to more than 20 buffalo in the largest. Large herd size is associated with home ranges that contain substantial areas of open habitat, and thus more food resources than forested habitats.     

Effect of reducing anatomic dead space on arterial PCO2 during CO2 inhalation

Carotid body-denervated (CBD) ponies have a less than normal increase in arterial PCO2 (PaCO2) when inspired CO2 (PICO2) is increased, even when pulmonary ventilation (VE) and breathing frequency (f) are normal. We studied six tracheostomized ponies to determine whether this change 1) might be due to increased alveolar ventilation (VA) secondary to a reduction in upper airway dead space (VD) or 2) is dependent on an upper airway sensory mechanism. Three normal and three chronic CBD ponies were studied while they were breathing room air and at 14, 28, and 42 Torr PICO2. While the ponies were breathing room air, physiological VD was 483 and 255 ml during nares breathing (NBr) and tracheostomy breathing (TBr), respectively. However, at elevated PICO2, mixed expired PCO2 often exceeded PaCO2; thus we were unable to calculate physiological VD using the Bohr equation. At all PICO2 in normal ponies, PaCO2 was approximately 0.3 Torr greater during NBr than during TBr (P less than 0.05). In CBD ponies this NBr-TBr difference was only evident while breathing room air and at 28 Torr PICO2. At each elevated PICO2 during both NBr and TBr, the increase in PaCO2 above control was always less in CBD ponies than in normal ponies (P less than 0.01). The VE-PaCO2, f-PaCO2, and tidal volume-PaCO2 relationships did not differ between NBr and TBr (P greater than 0.10) nor did they differ between normal and CBD ponies (P greater than 0.10). We conclude that the attenuated increase in PaCO2 during CO2 inhalation after CBD is not due to a relative increase in VA secondary to reducing upper airway VD.(ABSTRACT TRUNCATED AT 250 WORDS)     

The comparative aspects of spatial ecology of lizards exemplified by the toad-headed lizards (Reptilia, Agamidae, Phrynocephalus)

The possibility of analysis of phylogenetic parameters of the spatial distribution of populations is discussed by an example of the agamid toad-headed lizards (Phrynocephalus). Summarizing both original and published data on the individual home ranges and the relocation of individuals of 30 populations from 12 species showed that differentiation of the type of spatial distribution is weak in toad-headed lizards. This observation confirms the idea that this clade of agamids is phylogenetically young and relatively recently radiated. At the interspecific level, positive correlation between home range size and body size was observed in the studied group. Such spatial parameters, shared by all toad-headed lizards, as relatively large size and weakly structured individual home ranges can be explained by the peculiarities of their reproduction features and their foraging mode. The individual type of space-usage in toad-headed does not fit the traditional scheme dividing all the lizards into the territorial Iguania and the nonterritorial Autarchoglossa.     

High genetic connectivity and introgression from domestic reindeer characterize northern Alaska caribou herds

Defining genetic populations and detecting hybridization with introduced or domestic taxa are two major concerns for the conservation of population-level diversity. We studied the genetic population structure of large, migratory caribou herds (Rangifer tarandus granti) on Alaska’s North Slope and their potential hybridization with introduced domestic reindeer (R. t. tarandus). Using a population genetics approach, we determined: (1) whether the four caribou herds could be differentiated; (2) how distance and population size appear to drive genetic population structure; and (3) how contact with reindeer has affected the genetic identity of herds. Samples from four caribou herds (n = 245) and reindeer (n = 67) were analyzed at 19 microsatellite loci. We found that North Slope caribou are isolated by distance, with no differentiation among herd pairs except for the most geographically distant herds (F _st  = 0.003, Jost’s D = 0.023; P-values < 0.001). We detected reindeer-caribou admixture in all populations except Kodiak Island, including 8 % of individuals in caribou herds and 14 % of individuals in Seward Peninsula reindeer herds. However, considering the stable or increasing trend in North Slope herds, reindeer introgression has had no apparent deleterious effect on herd demographics. Our findings indicate long-term genetic exchange among North Slope caribou herds when their ranges overlap, and suggest that herd size may influence susceptibility to reindeer introgression. As North Slope herd ranges are increasingly altered by industrial development, this study can provide a baseline for detecting potential future impacts to what are currently large, diverse, and naturally evolving herds.     

Wide home ranges for widely foraging lizards

Space usage by animals may be influenced by a range of factors. In this study we investigate whether foraging behaviour affects the home range size of lizards. Two distinct tactics of foraging have been recognized in predators: sit-and-wait foraging (SW) and active foraging (AF). Foraging activity level of a data set of lizard species, mainly compiled from literature, is compared with their home range sizes. Two opposite predictions can be made about foraging in connection with home range area: on the one hand, SW species may exhibit larger home ranges due to their mating system; on the other hand, AF species have higher metabolic energy and thus food requirements and can be expected to have larger home ranges that have to yield this food. This study shows that percentage of the time moving (as an index of foraging mode) correlates positively with home range, even after correcting for body mass, and these patterns remain when phylogenetic relationships are taken into account. We thus conclude that home range areas parallel activity levels in lizards.     

Social Organization of Lepilemur ruficaudatus

We characterize the spatial organization of red-tailed sportive lemurs (Lepilemur ruficaudatus) as a key aspect of their social organization and social system. Sportive lemurs are small (<1000 g), nocturnal and folivorous primates endemic to Madagascar. We studied a population of 57 individually-marked individuals in Kirindy Forest, western Madagascar, between 1995 and 2001. We radio-tracked 20 males and 26 females of the marked population to obtain detailed information on the size and location of their home ranges. Census data and morphometric measurements provided complementary data sets. Males and females occupied small (<1 ha) home-ranges. Long-term records from 9 individuals revealed home-range stability over several years. In 4 cases home ranges overlapped extensively with that of one member of the opposite sex; in 2 cases, a spatial association of 1 male and 2 females occurred. However, home ranges overlapped very little with neighboring individuals of both sexes. During the study period, spatially associated individuals used on average 5.6 sleeping trees within 117 days, but they spent on average only about every fourth night together. The data suggest that home ranges in red-tailed sportive lemurs are exclusively used by pairs or trios and that the modal social organization of red-tailed sportive lemurs is pair-living.     

Land use patterns within Wattled Crane (Bugeranus carunculatus) home ranges in an agricultural landscape in KwaZulu-Natal,South Africa

There The Wattled Crane Bugeranus carunculatus is one of the top five most threatened bird species in South Africa, with the main threat being the loss of undisturbed breeding habitat. A basic understanding of this species' use of its environment is needed to implement conservation action. This quantitative study focused on determining the home range size of active breeding pairs in the KwaZulu-Natal midlands of South Africa, and assessing the land use composition of these home ranges. Wattled Cranes were found to have an average home range size of 16.64km², consisting mostly of open natural grassland (mean of 75.5% of the overall home range of pairs). Other significant land use contributions to the home ranges were temporary irrigated and dryland cultivated agriculture. The core breeding area (wetland) of the home range constituted only 2.3% of the overall home range size, consisting of similar proportions of both wetland (48.9%) and grassland (51.8%) habitat. This indicates the dependence of Wattled Cranes on specific wetland habitats, surrounded by natural grassland. Wattled Cranes show home range sizes larger than other similar-sized crane species, suggesting that this may be as a result of their large body size and their occupation of highly transformed and fragmented habitats in an agricultural landscape. However, the occurrence of transformed land use types in home ranges suggests that breeding pairs tolerate some degree of disturbance within their home ranges. The home ranges do not appear to be currently restricted by surrounding land use types, indicating that factors other than habitat loss may be contributing to breeding site losses. The study has therefore indicated the need for closer working relationships between conservationists and agricultural communities to promote the conservation of valuable natural grasslands surrounding wetlands.     

The Breeding System of the Acorn Woodpecker in Central Coastal California

Adult spatial relationships and social organization in a marked population of alpine mammals, the pika (Ochotona princeps), were studied over a 3-year period in the Rocky Mountains of Colorado. Home range size, distances between centers of activity of dyads, and weighted overlaps of home ranges of dyads were used to define space use patterns. Disappearance and establishment of individuals reflected the temporal component of space use. Relative frequencies of foraging (haying and feeding), surveillance, and communication (short calling, long calling, cheek rubbing) behaviors were recorded. Social relationships among adults were defined by agonistic interactions (aggression) and affiliative behaviors (social tolerance, vocal duets, copulations). Males and females occupied individual home ranges of equal size on talus, their obligate habitat type. Adjacent home ranges were normally occupied by pikas of the opposite sex. Replacement of home ranges was always by a member of the same sex as the previous occupant. A high degree of affiliative behavior was expressed between spatially contiguous heterosexual dyads. Aggression was greater among intrasexual than heterosexual dyads, and spatial overlaps among intrasexual conspecifics were less than among heterosexual conspecifics. Ecological constraints, such as the distribution of food (primarily located in meadows adjacent to the talus) and the short summer reproductive season (placing a premium on early appropriately timed litter;;) have apparently led to a facultatively monogamous mating system. Males can neither monopolize essential resources sufficiently to attract several females, nor defend groups of females as social repulsion among females further increases their dispersion.