The post-release survival of hand-reared tawny owls (Strix aluco) was measured using radio-tracking and leg-band return data. Of 16 birds fitted with 2.4 g radiotelemetry tags, two shed their tags after four and nine days, respectively and one bird was recovered and the tag removed. The remaining 13 birds were tracked for between 16 and 84 days (median 38). Of these, two were found dead (one emaciated and one predated) and one was recovered alive but emaciated and was subsequently euthanased. Thirty-seven percent were radio-tracked for more than six weeks, thought to be the critical period beyond which raptors will mostly survive. Of 112 birds banded between 1995 and 2005, 18 were recovered (seven live and 11 dead). Of the seven live recoveries, three were involved in road traffic collisions. Of the dead recoveries for which the cause of death was known (n = 4), all had been involved in road traffic collisions. The time elapsed between release and recovery ranged from 1–2,246 days (median 123 days). Over 65% survived for more than six weeks. The distance travelled between release and recovery ranged between 0 and 6 km (median 0). Further work is required on the effects of hand rearing on post-release survival of rehabilitated wildlife.

The release of animals from captivity frequently leads to a period of erratic movement behaviour which is thought to expose the animal to a high risk of mortality. Twenty-six foxes which had been reared at a wildlife hospital or captive-bred, were radio-collared when nearly full-grown and released without site acclimation. Immediately after release there was an erratic phase of behaviour, during which the foxes travelled widely and movement parameters were markedly elevated. For those foxes which survived, a second phase was entered after an average of 17.2 days, during which one small area only was used, and movement parameters were much reduced. In a second study, nine foxes were released following site acclimation in a pre-release pen; this process postponed but did not eliminate the phase of high movement activity.

This pattern of movement was compared with the dispersal behaviour of wild-reared foxes. It was concluded that released foxes, despite being proficient in other aspects of behaviour, were moving and behaving in a markedly abnormal manner and this resulted in a high death rate. The results are used to discuss methods of improving rehabilitation techniques.

We recently used radio-tracking to demonstrate short-term, post-release survival of five orphaned, hand-reared pipistrelle bats. Here, we present further evidence of short-term, post-release survival and also demonstrate longer term survival using re-sighting data of ringed common (Pipistrellus pipistrellus) and soprano (Pipistrellus pygmaeus) pipistrelle bats. Ten bats (five common and five soprano pipistrelles) were radio-tracked for between one and ten days. Three of these were retrieved after one, two and four days, respectively. In addition, five of the 39 (13%) ringed bats returned to their release boxes between 38 and 1,389 days after release, at least two of which survived over the winter in the wild. A sixth ringed bat was retrieved 27 days after release after becoming trapped in a house. We also identified potential barriers to successful rehabilitation. Two of the ten bats radio-tracked in the current project became trapped within buildings and another bat had to be retrieved following entanglement with debris. We therefore recommend that attention be paid to giving bats the opportunity, prior to release, in identifying and using small exit holes similar to those found in buildings and loft spaces. We also recommend allowing bats to self-release following prolonged pre-release flight training in a large flight cage situated in suitable bat habitat.

Mutualistic interactions are biologically important, diverse and poorly understood. Comprehending these interactions and the effectiveness of the mutualistic partners has been the central focus of ecological and evolutionary studies, as this task requires disentangling the pieces of mutualism under study. Here, we tested the hypothesis that feeding activity of Artibeus phaeotis influences density, diversity and distance effects of the seed rain of large-seeded plant species in a Neotropical dry forest of Costa Rica. We predicted that bats’ activity increases density and diversity metrics on dispersing sites and that bats behave as short-distance dispersers. Our data revealed that, by dispersing hundreds of seeds within their small foraging areas and mostly close to fruiting trees, the feeding activity of A. phaeotis increases the density and richness of seeds underneath night feeding roosts. The functional role of A. phaeotis as disperser may vary among plant species, as we also detected that some seeds are more dispersed than others. Further inquiries to elucidate mutualistic interactions between frugivorous bats and large-seeded plant species should focus on understanding demographic and fitness outcomes, as strong selective pressures may be shaping morphological and behavioural traits of both plants and animals, ultimately influencing the survival of each partner.

Species with specific habitat requirements often remain within their habitat and are characterized by a very sedentary behaviour. We used radio-tracking during a 3-wk campaign to investigate the home ranges and movements of three East African passerine bird species, all adapted to cloud-forest habitats: montane white-eye Zosterops poliogaster mbuluensis, stripe-cheeked greenbul Andropadus milanjensis and white-starred robin Pogonocichla stellata macarthuri. Individuals were observed in a forest-grassland mosaic on top of Chyulu Hills, south Kenya. Based on 15 individuals with a total of 1041 fixes, we found (1) that all three species show a sedentary behaviour restricted to their home forest patch; (2) least activity during the afternoon; and (3) re-colonization into its home patch after translocation into a nearby forest patch. Our findings underline that forest-specialist bird species of the tropics show high site fidelity despite their potential movement ability.

As most of the pristine forests of South-east Asia have been lost, the ability of its animal species to coexist with humans becomes increasingly important. Dian's tarsier Tarsius dianae, one of the smallest primates, lives in forests of central Sulawesi, Indonesia that are experiencing a dramatic increase in degradation by humans. To evaluate the effects of anthropogenic disturbance on tarsiers we used a comprehensive approach to estimate habitat suitability for these nocturnal insecthunters. On four study plots along a gradient of human land-use we determined population densities, home range sizes, nightly path lengths and group sizes of T. dianae. In total we captured 71 individuals and radio-tracked 30 of these. In more undisturbed sites, population densities were high and travel distances small. We found the smallest home ranges in slightly disturbed forest. In a heavily disturbed plantation densities were low, and ranges and nightly path lengths were large. These results show that undisturbed and slightly degraded forests are the most suitable tarsier habitats, and that focusing on different population parameters could lead to differing conclusions about the suitability of particular habitats.

Around the world, endemic species with restricted ranges seem to be at particular risk of extinction. When range size is controlled, lowland continental species may be especially at risk, more so than island or montane species. Our study aimed to investigate reasons behind the high vulnerability of endemic species. In Sri Lanka, large-scale national surveys and intensive localized fieldwork established that endemic plant and animal species are mostly associated with undisturbed rainforest habitats. On the other hand, non-endemic species used both forest and non-forest habitats almost equally, suggesting they are less likely to suffer from deleterious edge effects. To understand the different distribution of endemic and non-endemic species, our study focused on rats. Compared to the widespread species, the endemic rat species had a larger home range and fed on fewer species of forest fruit, possibly indicating greater specialization. The abundance of the endemic species was also negatively correlated with the abundance of the non-endemic species, to which it was behaviourally subordinate. Greater specialization and competitive inferiority could both contribute to the vulnerability of endemic species.

The spatial dispersion and social interactions were studied in 11 neighbouring pairs of radio-tagged tawny owls Strix aluco in a deciduous wood in Denmark from 1998–2001. The numbers and shapes of territories were stable throughout the survey and similar to a mapping made 40 years earlier. The home ranges of mates were of equal size and overlapped 82% in summer and 56% in winter. The inter-mate distances were on average 2.7% shorter than expected by chance. The activity distribution of neighbouring pairs overlapped 9% (95% CI: 2–15%) on average. Males and females did not differ in overlap with neighbours, and there was a similar overlap between neighbours of the same and opposite sex. Both sexes vocalized more often in the peripheries than in the centres of their territory. The vocal activity during May–September varied extensively among years and months in accordance with variation in the density of juvenile floaters. Males and females vocalized equally often and were involved in disputes with neighbours at similar rates. Usually, neighbouring disputes involved either one individual from each pair or all four. Disputes involving all four owls more often involved chasing and fighting than those involving one owl only from each pair. The dispute rate between neighbouring pairs correlated positively with home-range overlap. The total annual mortality was 21% (95% CI: 6–33%). Dead owners were usually replaced within 1–2 months. Two out of four cases of radio-tagged owls disappearing from their territory because of natural causes was due to take-overs by invading owls, suggesting that the risk of losing fitness resulting from eviction was important. The apparent co-operative territorial behaviour of tawny owl pairs is probably due to improved resource holding potential of pair coalitions compared to single individuals.

Monogamy in mammals is characterized by reduced sexual dimorphism in morphology and behaviour. Ten pairs of Eurasian beaver Castor fiber were radio-tracked to test how far this concept can be applied to movement behaviour by focusing on sex-related effects on territory sizes and movement patterns. Within monogamous pairs, males and females occupied territories of almost equal size during the whole radio-tracking period and more specifically after parturition. The territories of pair members overlapped on average by 81.6±14.0% SD while the territory overlap between residents and their neighbours was small to non-existent (on average between 0.5% and 2.2%). Males had larger 95% utility distributions than did females during the whole tracking period and after parturition. There was no significant difference between the 50% utility distributions for both sexes. Furthermore, males and females spent equal proportions of their time in territory border zones. There was a non-significant trend for males to move greater distances at night than females. Nightly distance moved correlated positively with territory size in females but not in males. Nightly distance moved correlated with neither body weight nor colony size. These results suggest that beavers show reduced sexual dimorphism in space use and movement patterns within adult monogamous pairs.

To determine the effects of their movement patterns, seven Cape clawless otters Aonyx capensis were caught in two rivers and radio-tracked between 1993 and 1995. Total range length varied from 4.9 to 54.1 km and core length from 0.2 to 9.8 km. Total area of water used varied between 4.9 and 1062.5 ha, and core areas from 1.1 to 138.9 ha. As predicted using the resource dispersion hypothesis, total home-range length was correlated with mean reed bed (high food density patch) nearest neighbour distance. The pattern of home-range use by females was suggestive of territoriality. Male Cape clawless otters had overlapping home ranges, both with other males and with females.

The knowledge of the ability of a species to adapt to a human-altered environment is important for developing wildlife management plans and, in turn, for conservation of the species. Radio-tracking was used to examine the effects of partial food or cover removal (owing to agricultural changes) on the spacing patterns and habitat use of adult roe deer Capreolus capreolus in a mixed wood/agricultural Mediterranean area, during spring–summer 1996–97. For both sexes, there were no changes in home-range and core-area sizes, or in inter-fix distances, after food (field ploughing) or cover (crop harvesting) removal. After food removal, both sexes shifted their home ranges and core areas, spending more time in woodland and less time in the ploughed field. This suggests a change in feeding habits. In addition, similar responses by males and females indicate that their energetic requirements are comparable during the territorial/reproductive period. After removal of cover, males neither shifted their home ranges and core areas, nor changed their habitat use, whereas females responded with significant shifts (by c. 90%) of the core area, and a significant decrease in the proportion of daytime spent in the harvested field. Thus, crop harvesting in this period (May/June) has different effects on the two sexes, with adult females being much less tolerant than males. Differential responses to cover removal were related to the different security requirements of the two sexes around the period of parturition.

The spatial resources used by a population of lace monitors (Varanus varius) were examined over an active season (September–April) and an inactive season (May–August). In total, 33 monitors were observed, of which 23 monitors were radio-tracked for up to 11 months. Radio tracking provided new information on the spatial ecology of V. varius. During summer (December–February), V. varius moved often, over large (184.5 ha) overlapping home-range areas. In the intermediate seasons of spring (September–November) and autumn (March–May), monitors moved less often and used less than 39% of the summer home-range. Finally, in the cold winter season (June–August) many monitors did not move at all and most used less than 5% of their summer home-ranges. The thermal environment, and reproductive status of V. varius affected its use of space, and the importance of these factors varied seasonally. No spatial segregation was noted between monitors, with home-ranges overlapping on average for eight other radio-tracked monitors. The home-range size of V. varius was accurately predicted using published data on body mass and home-range size for the Varanidae.

Miniature radio-transmitters were used to follow movements over a 10-day period of the 10 g honey possum Tarsipes rostratus, and the areas covered were compared with home-range estimates calculated from long-term mark-and-recapture records using pitfall traps. The study was carried out in the Scott National Park, in the extreme south-west of Western Australia, and shows that honey possums may move far greater distances than is apparent from trapping records. The overall mean area used determined by radio-tracking was significantly larger at 0.54±0.19 ha than the apparent home range of 0.03 0.01 ha determined by trapping. The area used by males was significantly greater than that of females when measured by radio-telemetry (0.79±0.24 ha vs 0.14±0.08 ha, P = 0.058), but did not differ significantly when estimated from trapping records (0.03±0.01 ha vs 0.01±0.01 ha). These data suggest that honey possums frequent plant assemblages at night where they are vulnerable to pitfall trapping, but that males, particularly, spend the day in other areas that may be as far as 200 m distant.

The use of breeding dens and the early kitten development was studied in a free-ranging population of Iberian lynx Lynx pardinus. Radio-tracking of female lynx allowed intensive monitoring of three litters during 1997, and additional data to be obtained from nine other litters in the previous 4 years. Females gave birth a maximum of one litter per year in spring; nine of the 10 births were recorded between the last 2 weeks of March and the first days of April. Kittens were born semi-altricial and reared for nearly 20 days in secluded hollow trunks. Afterwards, they were moved between different bushes, which served as auxiliary dens, where they began to develop walking and senses. Kittens first consumed meat at the age of 4 weeks, although they were not fully weaned until they were at least 10 weeks old. At the age of 2 months, kittens began to leave the dens, accompanying their mothers on outings. It is suggested that the pattern of den use was related to the stage of kitten development, to fulfil the kittens' need for both protection and space as they grew. Data on kitten denning and development should be accounted for in in-situ and ex-situ conservation programmes for this endangered felid.

Thirty-six of the 70 species of bats known from Belize were recorded from the area around Lamanai, Orange Walk County: two in roosts and 34 in about 680 mist net hours that produced 560 captures. Day roosts used by 35 of the species were located using radio-tracking (Sturnira lilium, Platyrrhinus helleri, Centurio senex and Bauerus dubiaquercus) or general searching for roosts (Rhynchonycteris naso, Saccopteryx bilineata, Saccopteryx leptura, Dicli durus albus, Mimon bennettii, Micronycteris schmidtorum, Carollia brevicauda, Carollia perspicillata and Eptesicus furinalis). Data on the day roosts of 23 other species were determined from the literature. Most species reported from Lamanai (19) roosted in hollows, while others used foliage (6), tents (3), sheltered sites (2), crevices (2), open sites (1), and a few species used more than one type of day roost (hollows and crevices (1); hollows and foliage (1); hollows, foliage and tents (1)). The fauna consisted of 13 aerial foragers, 9 gleaners, 11 fruit/leaf eaters, one trawler, one flower-visitor and one blood-feeder. In day roost use and foraging behaviour, the Lamanai fauna did not differ significantly from that of Paracou, French Guiana, but both these locations differed from the bat fauna of Kruger National Park, South Africa, in foraging behaviour.

Two newt species with contrasting ecological requirements (Triturus cristatus and T. marmoratus) were radio-tracked after leaving a shared breeding pond in western France. Movements of 30 individuals were recorded over 491 days. During the first terrestrial night, the newts migrated with high directionality up to 137 m to their refuges. Burrows of small mammals were among the favourite refuges. Movements after the first night were mostly underground and over shorter distances (< 6.8 m). Sixty-four per cent of all tracked newts stayed within 20 m of the pond edge, and migrations were recorded up to 146 m away from the pond. Both species preferred areas with bushes, hedgerows and trees, and avoided pastures and open areas. Migration in the direction of a habitat type characterized by trees and underground shelters was favoured over migrations in other directions. A clear terrestrial niche separation between the two newt species was not observed. The results are discussed in relation to previous findings that T. cristatus supersedes T. marmoratus as a consequence of anthropogenic change to the terrestrial environment, affecting the species differentially.

The final phase of spawning migration of eight adult male Atlantic salmon, Sulnio solar L., was analysed by radio-tracking in relation to sea age and size in a spawning tributary of the Kiver Sélune. Four grilse and four multi sea-winter fish, one of which as a previous spawner, were radio-tagged and released. Their fork length ranged from 602 to 882 mm. The daily movement in the first two days alier release and the furthest upstream distance recorded from the trap during the study period were independent of fish length. Maximum amplitude of movement observed over the entire study period was inversely correlated with length. Daily movement decreased in all males during the spawning period and was negatively correlated with the size of fish. Surviving males remained in the vicinity of the spawning grounds after spawning. It was concluded that the length of male seemed to influence its behaviour in the last phase of the spawning migration, enabling a much more successful participation of the larger males in spawning.