Animal Conservation - Current Issue

Volume 8 Issue 04

Tue, 01 Nov 2005 00:00:00 GMT

Animal Conservation, Volume 8 Issue 04

Animal Conservation provides a forum for rapid publication of novel, peer-reviewed research into conservation of animal species and their habitats. The focus is on rigorous studies of an empirical or theoretical nature. Studies may relate to populations, species, or communities but should have broad conservation significance. A central theme is to publish important new ideas and findings from evolutionary biology and ecology that contribute towards the scientific basis of conservation biology. Subjects covered by the journal include behaviour and population biology; wildlife disease and epidemiology; evolutionary ecology and genetics; systematic biology and phylogenetics; biodiversity and biogeography; management (including translocation and sustainable use). The journal is essential reading for conservation biologists, policy-makers and students.

Translocation as a conservation tool: site fidelity and movement of repatriated gopher tortoises ( Gopherus polyphemus )

Research Articles
Tracey D. Tuberville, Erin E. Clark, Kurt A. Buhlmann, J. Whitfield Gibbons,
Animal Conservation, Volume 8 Issue 04 , pp 349-358

Abstract
Efforts to evaluate the efficacy of translocation as a conservation tool have mostly been inadequate, particularly for reptiles and amphibians, leading many biologists to discount translocation as a viable management option. Nevertheless, with two-thirds of the world s tortoise and freshwater turtle species at risk, translocation may be one of the few remaining options for re-establishing extirpated populations and reconnecting fragmented ones. We translocated 106 gopher tortoises (Gopherus polyphemus) to a protected area within the historical range but with no resident tortoises and tested the effects of penning on site fidelity and activity area size. We assigned 38 adults and subadults to one of three penning treatments (9 months, 12 months and no penning) and radio-tracked them for 2 years. Penning significantly increased site fidelity and resulted in smaller activity areas. Our data suggest that translocation coupled with penning will improve the likelihood of establishing self-sustaining tortoise populations.

Modelling impacts of long-line fishing: what are the effects of pair-bond disruption and sex-biased mortality on albatross fecundity?

Research Articles
Michael S. L. Mills, Peter G. Ryan,
Animal Conservation, Volume 8 Issue 04 , pp 359-367

Abstract
Long-line fishing mortality poses a significant threat to many large procellariiform seabirds. To date, estimates of impacts have concentrated on lower survival rates, largely ignoring the costs to fecundity resulting from disruption of breeding pairs and skews in sex ratio. A comparative, stochastic, individual-based model was used to investigate these costs for the wandering albatross Diomedea exulans. Ignoring the time taken to replace a lost mate overestimates fecundity by 13 18%, resulting in annual population growth rates ( ) being 0.006 0.007 too high. Long-line mortality exacerbates this cost, which becomes more substantial with increasing demographic skew resulting from female-biased mortality. At moderate levels of long-line mortality (2 4% per year), 80% female-biased mortality reduces fecundity by 9 27% and by 0.003 0.010 relative to models with random mortality. Biased sex ratios accumulate and, unlike reduced survival, their impacts on albatross demography persist after long-line mortality ceases. Estimates of the demographic costs of long-line mortality should incorporate individual-level effects, especially where mortality is sex-biased.

The response of tree squirrels to fragmentation: a review and synthesis

Research Articles
John L. Koprowski,
Animal Conservation, Volume 8 Issue 04 , pp 369-376

Abstract
Habitat fragmentation is often considered a major threat to biodiversity; however, our understanding of how fragmentation impacts populations is poor. Identifying appropriate models for such studies is difficult. Tree squirrels are dependent on mature forests for food, cover and nests; these are habitats that are being fragmented rapidly and that are easily defined by humans. Squirrels represent excellent models for study of fragmentation. The literature on tree squirrels was reviewed to glean data on density and home-range size in forest fragments. Sufficient data were available on four species (Sciurus carolinensis, S. niger, S. vulgaris, Tamiasciurus hudsonicus). Density was negatively related to fragment size for S. carolinensis and S. niger and marginally so for T. hudsonicus. Sciurus vulgaris did not exhibit this relationship. Home-range size was analysed for three species of Sciurus and was positively related to forest fragment size for S. carolinensis and S. niger. Again, only S. vulgaris did not to show this relationship. Sciurus vulgaris is rarely found in small forest fragments and is believed to be especially sensitive to fragmentation; other tree squirrels appear to be sensitive to fragmentation in more subtle ways. Home range compaction provides a mechanism by which densities may increase in small fragments. The demographic consequences resultant from the high densities of squirrels found in small woodlots are not known but may explain the forest damage, avian nest predation and reduced diversity often cited to occur in woodland fragments.

Population genetic structure and conservation of Asian elephants ( Elephas maximus ) across India

Research Articles
T. N. C. Vidya, P. Fernando, D. J. Melnick, R. Sukumar,
Animal Conservation, Volume 8 Issue 04 , pp 377-388

Abstract
This study examines the population genetic structure of Asian elephants (Elephas maximus) across India, which harbours over half the world s population of this endangered species. Mitochondrial DNA control region sequences and allele frequencies at six nuclear DNA microsatellite markers obtained from the dung of free-ranging elephants reveal low mtDNA and typical microsatellite diversity. Both known divergent clades of mtDNA haplotypes in the Asian elephant are present in India, with southern and central India exhibiting exclusively the clade of Fernando et al. (2000), northern India exhibiting exclusively the clade and northeastern India exhibiting both, but predominantly the clade. A nested clade analysis revealed isolation by distance as the principal mechanism responsible for the observed haplotype distributions within the and clades. Analyses of molecular variance and pairwise population FST tests based on both mitochondrial and microsatellite DNA suggest that northern-northeastern India, central India, Nilgiris (in southern India) and Anamalai-Periyar (in southern India) are four demographically autonomous population units and should be managed separately. In addition, evidence for female philopatry, male-mediated gene flow and two possible historical biogeographical barriers is described.

The influence of spatial grain size on the suitability of the higher-taxon approach in continental priority-setting

Research Articles
Frank Wugt Larsen, Carsten Rahbek,
Animal Conservation, Volume 8 Issue 04 , pp 389-396

Abstract
The higher-taxon approach may provide a pragmatic surrogate for the rapid identification of priority areas for conservation. To date, no continent-wide study has examined the use of higher-taxon data to identify complementarity-based networks of priority areas, nor has the influence of spatial grain size been assessed. We used data obtained from 939 sub-Saharan mammals to analyse the performance of higher-taxon data for continental priority-setting and to assess the influence of spatial grain sizes in terms of the size of selection units (1 1 , 2 2 and 4 4 latitudinal longitudinal quadrates). Independent of spatial grain size, the selection of priority areas based on genus data is more effective than the random selection of these areas, while the selection of priority areas based on family data is less effective than random selection. Compared to selection based on species data, genus-based priority areas represent between 5 14% fewer species, but represent even fewer of the threatened species (6 31%) and range-restricted species (7 42%) that are normally considered most valuable for conservation. While genus-based priority areas for the 4 grain size represent species almost as effectively as species-based priority areas, genus-based areas perform considerably less effectively than species-based areas for the 1 and 2 grain size. Thus, our results favour the higher-taxon approach for continental priority-setting only when large grain sizes ( 4 ) are used.

Habitat use of the endangered iguana Cyclura lewisi in a human-modified landscape on Grand Cayman

Research Articles
Rachel M. Goodman, Frederic J. Burton, Arthur C. Echternacht,
Animal Conservation, Volume 8 Issue 04 , pp 397-405

Abstract
Cyclura lewisi is an endangered rock iguana endemic to the island of Grand Cayman. Like many other animals, C. lewisi increasingly depends on modified landscapes for its survival. The remaining natural population is too small and fragmented to yield information on the natural history and population biology of this species. Therefore, we studied habitat use in a population of captive-bred, released iguanas in a botanic park. Compositional analysis was used to examine habitat selection and use by iguanas at two scales: selection of home range within the landscape and selection of locations within home ranges. At both scales and for all time periods examined, iguanas preferred modified habitat to natural habitat. Subhabitats were examined only at the scale of selection within the landscape, for which iguanas showed preference in some but not all time periods. Iguanas used artificial retreats more often than natural retreats and commonly occupied retreats in modified areas. Many female iguanas nested in artificial sites within the park. The use of modified habitats and artificial retreats and nests by reintroduced C. lewisi is encouraging, because this and other species of Cyclura may depend on these resources for future survival.

The morphology, and hence impact, of an invasive species (the cane toad, Bufo marinus ): changes with time since colonisation

Research Articles
Ben L. Phillips, Richard Shine,
Animal Conservation, Volume 8 Issue 04 , pp 407-413

Abstract
Successful invasive species often exhibit high phenotypic lability. Even when intuition suggests that their genetic diversity has been reduced by strong founder effects, many successful invasive species still exhibit adaptive change in response to their new environment. To understand the probable long-term ecological impacts of a particular invader, we need to quantify long-term changes in the invader s phenotype, as these changes may well influence the level of impact the invader has on native species. Here we examine morphological change, as a consequence of time since colonisation and other spatial factors, in the cane toad (Bufo marinus). Cane toads are highly toxic and have killed many Australian native predators since they were introduced in 1935. The amount of toxin to which a predator is exposed will depend upon (1) the body size of the toad and (2) the relative toxicity of the toad (here measured by the relative size of the toad s parotoid glands). Using multiple regression and a model-selection approach, we show that both toad size and relative toxicity have decreased with time since colonisation. Thus toads (like many other successful invasives) exhibit phenotypic lability. Importantly, this result strongly suggests that toads will exert their maximal impact on native predators when they first arrive in an area; the level of impact will then decline over time.

Successful island reintroductions of New Zealand robins and saddlebacks with small numbers of founders

Research Articles
Sabrina S. Taylor, Ian G. Jamieson, Doug P. Armstrong,
Animal Conservation, Volume 8 Issue 04 , pp 415-420

Abstract
Populations established with a small number of founders are thought to have a high risk of extinction due to allee effects, demographic stochasticity, inbreeding and reduced genetic variation. We tested whether the initial number of birds released was related to persistence in reintroductions of saddlebacks (Philesturnus carunculatus) and robins (Petroica australis) to New Zealand offshore islands. Data were analysed for 31 populations that had been observed for at least 3 years since reintroductions. The numbers released ranged from 5 188. Most of the populations (26) survived and grew, including five from less than 15 founders, and four out of the five extinctions were attributable to introduced mammalian predators. The number of individuals released did not significantly affect extinction probability. The ability of these small releases to establish populations can be attributed to the closed nature of the islands (allowing birds to find mates), low mortality rates following release and high growth rates at low density. Stochastic simulation models based on data from two reintroduced populations suggested that populations with four founders (two male, two female) would have a negligible chance of extinction through demographic stochasticity and would be able to grow even if there were high rates of egg failure through inbreeding.

Corridors affect dispersal initiation in reintroduced peregrine falcons

Research Articles
Matthew R. Dzialak, Michael J. Lacki, Jeffery L. Larkin, Kristina M. Carter, Shawchyi Vorisek,
Animal Conservation, Volume 8 Issue 04 , pp 421-430

Abstract
We reintroduced 33 peregrine falcons (Falco peregrinus) at two release areas with contrasting habitat configurations to assess landscape influences on dispersal. One site (Daniel Boone National Forest) had non-forested corridors within a forest matrix, whereas the other site (Tom Dorman State Nature Preserve) had forested corridors within an agricultural matrix. We used aerial telemetry and ground observation to assess differences in dispersal between sites and we used multivariate statistical analyses to detect combinations of response variables depicting landscape influences. Non-forested corridors at Daniel Boone affected post-fledging movements and initiation of dispersal, whereas no discernable pattern in dispersal initiation was observed at Dorman Preserve. Results included significant (p 0.05) differences between peregrines at Daniel Boone and Dorman Preserve in $\bar{x}{\pm}$ SD post-fledging area (PFA) size (2643.5 2599.0 and 931.7 732.1 ha, respectively), maximum movement distances (12.9 13.9 and 6.1 4.6 km, respectively), orientation of movements (second-order $\bar{x}$ angle 95% confidence interval (CI)=280.8 58.6 (non-random orientation) and 358.8 98.8 (random orientation), respectively), time spent on the PFA (16.0 12.2 and 31.0 3.3 days, respectively) and selection of agricultural habitats (Euclidean distance vectors =0.66 and =2.50, respectively). Selection of agriculture by peregrines released on Daniel Boone reflected selection of corridors as part of pre-dispersal movement. These results, coupled with generally unorientated movement behaviour by Dorman Preserve peregrines, provided evidence for an influence of functional landscape connectivity on dispersal in peregrines.

The impact of historical and recent factors on genetic variability in a mountain frog: the case of Rana iberica (Anura: Ranidae)

Research Articles
I. Martínez-Solano, I. Rey, M. García-París,
Animal Conservation, Volume 8 Issue 04 , pp 431-441

Abstract
Rana iberica is an Iberian endemic with populations mainly distributed in northwestern Iberia, but with scattered populations along the Sistema Central in central Spain. These latter populations inhabit mostly mountain areas and are endangered due to habitat loss and fragmentation. At present, no information about genetic variability and gene flow patterns between populations is available and, consequently, it is unknown to what extent geographical fragmentation might have caused restrictions to gene flow. We used six microsatellite loci to characterise genetic variability in R. iberica populations from the Sistema Central. We analysed samples of 142 specimens from 15 populations in this region and another two from additional locations in the Iberian Peninsula. The number of alleles per locus observed ranged from four to 15. Allelic richness, percentage of private alleles and gene diversity was significantly lower in populations from the Sistema Central, where inbreeding coefficients were relatively high. Analysis of molecular variance (AMOVA) and estimated FST values indicated the existence of genetic substructuring within this region and suggested the existence of restrictions to gene flow in geographically close populations. Low heterozygosities and a trend towards lower values of genetic variability from western to eastern populations within the Sistema Central suggest that R. iberica has colonised this region recently. We hypothesise that the observed pattern is due to the interaction of both historical (reduced genetic variability in peripheral populations) and present-day (anthropogenic habitat loss) factors that confirm the vulnerable status of populations of R. iberica in central Spain and point to the need for adopting measures directed towards the preservation of existing habitat.

Are timber harvesting and conservation of nest sites of forest-dwelling raptors always mutually exclusive?

Research Articles
Asko Lõhmus,
Animal Conservation, Volume 8 Issue 04 , pp 443-450

Abstract
Many diurnal raptors are vulnerable to modern forestry and areas surrounding individual raptor nests are often strictly protected. This study compared random forest plots and nest sites of five species of forest-dwelling raptors in Estonia to explore whether timber harvesting per se reduces the probability of raptor nesting when controlling for the effect of nest tree availability and stand structure. Medium-sized species the honey buzzard (Pernis apivorus), goshawk (Accipiter gentilis), common buzzard (Buteo buteo) and lesser spotted eagle (Aquila pomarina) preferred natural to managed forests but the preference, when controlling for other stand characteristics, was not significantly related to the incidence of cutting. Instead, the presence of nests depended on structural features of old growth, even for the sparrowhawk (Accipiter nisus), which preferred young secondary forests. The sparrowhawk was the only species for which thinning had an independently negative influence on nest presence. The results stress the importance of structural diversity of forest stands in multiple-use forestry and indicate that if natural stand structure is preserved and disturbance avoided in buffer zones around the nests of medium-sized raptors, some non-commercial cutting (firewood collecting, sanitary cutting) may be allowed there outside the breeding season.