Kathy H. Hodder

Translocations of native species in the UK : implications for biodiversity

Native species are translocated for conservation, commercial, amenity and research purposes. These activities are related, and need to be considered and planned in terms of their effects on biodiversity. Procedures for assessing, implementing and regulating translocations have, however, been subject to largely uncoordinated development; recommendations or guidelines being produced separately for each area of expertise. There is a need to pull together the profuse information concerning specific translocations in order to present a broad approach to the general problems and concerns. Here, the extent and nature of translocations of native species within the UK are reviewed, and recommendations for policy and legislation are made in the context of those currently in use in the UK. The recommendations include the following: (i) improvement of the ways in which relevant information is disseminated; (ii) ease of implementation should be a prime consideration; and (iii) formation of new policy and guidelines should include all UK and international organizations involved in carrying out, advising on, or licensing translocations.

DENSITY AND LINKAGE ESTIMATORS OF HOME RANGE: NEAREST-NEIGHBOR CLUSTERING DEFINES MULTINUCLEAR CORES

Methods used to estimate home ranges from point locations are based either on densities of locations or on link distances between locations. The density-based methods estimate ellipses and contours. The other class minimizes sums of link distances, along edges of polygons or to range centers or between locations. We propose a new linkage method, using nearest-neighbor distances first to exclude outlying locations and then to define a multinuclear outlier-exclusive range core (OEC) by cluster analysis. The assumption behind exclusion of outliers, that movements inside and outside range cores involve different activities, was supported by data from radio-tagged Common Buzzards (Buteo buteo). We compared the new method with other techniques by using location data from each of 28 goshawks, 114 buzzards, 138 gray squirrels, and 14 red squirrels. Range structure statistics from OECs showed marked differences between species in numbers and extent of core nuclei. Range analysis displays illustrated relationships of range area with age categories, food supply, population density, and body mass within species. The OECs gave highly significant results in three of five within-species tests, perhaps because animal movements in these cases were affected by coarse-grained habitat boundaries. When movements were likely to have been influenced by diffuse social interactions and foraging for scattered prey, the most significant results were from density-based estimators, especially kernel contours that had been optimized by least-squares cross validation. We recommend use of both density and linkage estimators of home range until a basis for a priori choices has been established.

Techniques for evaluating the spatial behaviour of river fish

Radio-tagging is widely used for studies of movements, resource use and demography of land vertebrates, with potential to combine such data for predictive modelling of populations from individuals. Such modelling requires standard measures of individual space use, for combination with data on resources, survival, dispersal and breeding. This paper describes how protocols for efficient collection of space-use data can be developed during a pilot study, and reviews the ways in which such data can be used for space-use indices that help answer biological questions, with examples from a study of riverine pike (Esox lucius). Analyses of diurnal activity and spatio-temporal correlation were used to assess when to record locations, and analyses of home range increments were used to define the number of location records necessary to assess seasonal ranges. We stress the importance of developing protocols that use minimal numbers of locations from each individual, so that analyses can be based on samples of many individuals. The efficacy of link-distance (e.g. cluster analysis) and location density (e.g. contouring) techniques for spatial analysis for river fish were compared, and the utility of clipping off areas to river banks was assessed. In addition, a new automated analysis was used to estimate distances along river mid-lines. These techniques made it possible to quantify interactions between individuals and their habitat: including a significant increase in core range size during floods, significant preference for deep pools, and a lack of exclusive territories.

Is early dispersal enterprise or exile? Evidence from radio-tagged buzzards

In order to test whether Common Buzzards Buteo buteo that dispersed early were entrepreneurs or exiles, we determined standardised autumn ranges by radio-tracking 67 juveniles during 1990-94. Of these, 11 had dispersed more than 2 km from their natal nest, and had therefore left the natal territory. Buzzards that dispersed early had more fragmented ranges than those that delayed dispersal until the following spring; otherwise no range characteristic differed between the two groups. When only the dispersers were considered, increase in distance from the natal nest was associated with a decrease in range size (r = 0.74) and an increase in the proportion of arable land within the range (r = 0.77). Further investigation revealed that range size was affected by distance from the nest but not by arable habitat. The smaller range size of distant dispersers, combined with evidence of increased productivity among them, suggests that they were more likely to have been entrepreneurs than exiles.

Does landscape-scale conservation management enhance the provision of ecosystem services?

Biodiversity conservation approaches are increasingly being implemented at the landscape-scale to support the maintenance of metapopulations and metacommunities. However, the impact of such interventions on the provision of ecosystem services is less well defined. Here we examine the potential impacts of landscape-scale conservation initiatives on ecosystem services, through analysis of five case study areas in England and Wales. The provision of multiple ecosystem services was projected according to current management plans and compared with a baseline scenario. Multicriteria analysis indicated that in most cases landscape-scale approaches lead to an overall increase in service provision. Consistent increases were projected in carbon storage, recreation and aesthetic value, as well as biodiversity value. However, most study areas provided evidence of trade-offs, particularly between provisioning services and other types of service. Results differed markedly between study areas, highlighting the importance of local context. These results suggest that landscape-scale conservation approaches are likely to be effective in increasing ecosystem service provision, but also indicate that associated costs can be significant, particularly in lowland areas.

A simple activity monitoring radio tag for fish

A radio tag is described which facilitates the long-term monitoring of activity events in fish. The tag is a simple peritoneal implant and thus requires no complicated surgery to deploy. A motion-sensing mercury switch interfaced to a microcontroller is used to modulate pulse rate and thus indicate periods of activity. The tag is being used to study the feeding and activity patterns of pike (Esox lucius L.) where laboratory and field trials have shown the system to be robust, long lasting and reliable.

Rapid sustainability modeling for raptors by radiotagging and DNA-fingerprinting

Abstract Sustainable use of wildlife is crucial to ensuring persistence of natural resources. We used age-specific survival and breeding data to parameterize a demographic model for a harvested Kazakh saker falcon (Falco cherrug) population by radiotagging juveniles and estimating adult turnover with DNA-fingerprinting during 1993–1997. We gathered similar data during 1990–1998 to model populations of British buzzards (Buteo buteo), and during 1980–1998 to model populations of Swedish goshawks (Accipiter gentilis). Leg-bands and implanted microtransponders provided ways to test for bias and to estimate the harvest of sakers for falconry. Despite an estimated minimum first-year survival of only 23%, the observed productivity of 3.14 young per clutch would sustain a saker population (i.e., λ = 1) with a breeding rate (at laying) of only 0.63 for adults or with a residual juvenile yield of 37% if all adults breed. Higher first-year survival rates for goshawks and buzzards correlated with juvenile yields of up to 71%, but no more than half as many individuals if adults also were harvested. An annual population decline of 40% for sakers in southern Kazakhstan could be explained by observed productivity of only 0.71 young per clutch if there was also an estimated harvest of 55% of adults. This study shows that demographic models such as these can now be built rapidly if nestlings are fitted with reliable and safe radiotags and adult turnover is estimated from genetic analyses or other techniques.