In recent years, much progress has been made in non-invasive genetic methods for various purposes including population estimation. Previous research focused on optimising laboratory protocols and assessing genotyping errors. However, an important source of bias in population estimates still remains in the field sampling methods. The probability of animals being sampled can vary according to sex, age, social status or home-range location. In this article, we present relevant literature reviewed to provide an overview of the occurrence of individual heterogeneity (IH) in the field, and how it can be minimised, e.g. by adaptation of sampling design. We surveyed 38 articles describing non-invasive population estimation for 12 mammal and two bird species. The majority of these studies discussed IH as a potential problem. The detectability of IH via goodness-of-fit testing depended on the average capture probability reported in the studies. Field tests for assessing variation in sampling probabilities or validating estimations were carried out in only 11 of the 38 studies. The results of these tests point out that IH is a widespread problem in non-invasive population estimation, which deserves closer attention not only in the development of laboratory protocols but also concerning the sampled species' characteristics and the field methods. IH can be reduced in the field by carefully adapting the sampling design to the characteristics of the studied population. If this is not reasonable, it may be better to switch to a different sampling strategy.

Hunting disturbance may affect individuals in a population by modifying their behaviour and spatial movements, which can lead to changes in home-range size and habitat use or displacement, for example into refuge areas. To evaluate effects of disturbance by recreational hunting activity, we conducted a study with 87 individually radio-marked willow ptarmigan Lagopus lagopus, in experimentally hunted and non-hunted units in central Norway during a four-year period. Contrary to a common belief among many hunters, i.e. that willow ptarmigan abandon a hunting unit in response to hunting activity, none of the birds left hunted units during the first two weeks of the hunting season in our study. Neither, did hunting affect the size of areas used by the ptarmigan or the distance between locations on consecutive days. In fact, day-to-day movements tended to be longer in non-hunted units than in hunted units. Willow ptarmigan responded to the risk of being shot by increasing their use of habitat with dense forest/scrub cover, which provided secure escape sites where birds were more difficult to locate and to shoot by hunters using pointing dogs. The increased use of cover with secure escape sites found for willow ptarmigan indicates that the catch per unit effort of hunters will vary not only with population density, but also with the amount and distribution of dense forest/shrub habitat in hunted units. Where the site-specific catch per unit effort of hunters is difficult to predict, we recommend a management scheme of harvests based on allowing a predefined number of hunters to hunt for the whole season and a seasonal bag limit per hunter.

Declines of Alpine black grouse Tetrao tetrix populations have been linked to increasing disturbance by recreation and degradation of breeding habitat due to changes in land-use, especially abandonment of traditional farming practices. Appropriate forest, shrubland and grassland management may mitigate the negative effects of land abandonment. The habitat associations and trophic requirements of brood-rearing Alpine black grouse hens were appraised to inform effective habitat management policies. We measured the abundance, biomass and phenology of arthropods, a key food source for grouse chicks, in eight timberline habitat categories and performed a habitat selection analysis based on radio-tracking data collected from eight brood-rearing hens in the Swiss and Italian Alps. Arthropod biomass differed significantly between habitat categories and peaked in early summer due to a sharp increase of orthopterans (Saltatoria), an essential food source for Alpine black grouse chicks. Open grassland and grassy shrubland yielded the highest arthropod biomass, with Saltatoria dominating the sample. Yet, brood-rearing hens avoided open grassland, opting for a mosaic of grassy shrubland with scattered trees. Chick-rearing hens apparently traded-off food abundance for reduced predation risk, i.e. habitats offering cover for concealment and escape from predators. These specific black grouse breeding habitat requirements inform about habitat management within Alpine timberline ecosystems. Managers should not restore extensive, homogeneous pasturelands. Instead, a complex heterogeneous habitat mosaic, consisting of patches of grassland and shrubland interspersed with scattered coniferous trees should be promoted.

The fox tapeworm Echinococcus multilocularis occurs across large areas of Europe, Asia and North America. In people it may cause the zoonotic infection alveolar Echinococcosis (AE). Incurable and fatal if left untreated, it therefore requires costly, intensive and lifelong medication. To ensure efficient use of resources it is crucial to know where counter-measures are most beneficial. To assist prevention efforts, we developed a model based on prevalence rates in red foxes Vulpes vulpes, fox population densities, fox defecation rates and human population densities. Our aim was to estimate and gain insight into the intensity of contamination in different environments and the relative probability of people coming into contact with tape worm eggs. Based on data from six Bavarian regions, there was a strong positive correlation (Pearson r = 0.970, P ≤ 0.001) between human cases of AE and the relative probability of contact calculated using this model. Furthermore, the example calculations showed that due to the higher fox population density, just as much infectious material is released into the environment per day and per km² in urban areas with low prevalence of fox tapeworms (10%) as is in rural areas with high prevalence (80%). If human population density is also taken into account, the likelihood of contact between people and infectious faeces is higher in suburban/urban than in rural areas. For example, in 2005 the likelihood of contact was 45 times higher in the city of Munich than the Bavarian average. Our model thus confirms the hypothesis of Deplazes et al. (2004), which emphasises the substantial risk presented to humans by fox tapeworms in suburban areas, and it calls for counter-measures.

It is a very important, but also a very difficult task, to establish how long a certain species has to remain unregistered before we can declare it extinct. The wrong assumption regarding species extinction could result in a type I or type II statistical error, leading to inappropriate management actions or even species extinction. Recent development of the methods for inferring the threat of extinction, when the only available information is a record of sightings, has enabled a quantitative approach to the problem. In our study we present an index that infers extinction probability based on trends in sighting intervals. Our study comprises a description of the sighting trend index, a sensitivity analysis and an application of the index to the sighting record of the black-footed ferret Mustela nigripes. The main advantage of this method could be its sensitivity to changes in sighting frequency within the sighting record. However, further testing of the method on different data sets could be important for gaining additional knowledge regarding its adequate application in the field of conservation biology.

The American mink Neovison vison is a widely distributed species in Spain, for which important basic ecological data are lacking. We studied mink den site selection in a location in central Spain during the winter of 2008/09 using snow-tracking and direct observation. Dens were located more frequently in tree roots (51.9%; N = 79) inside emergent vegetation (15.2%) and on human-created enbankments (15.2%). Human buildings and burrows were scarcely used (< 10%). The logistic regressions we carried out supported that minks used secondary river beds for shelter more often than their availability in the environment should predict. These secondary areas are characterised by their low width and the frequent presence of small streams (of < 1m width). In rough terms, this pattern could be a way of avoiding potential interactions with other animals sharing the same habitat, and also for thermoregulation while resting. On the basis of the wide habitat niche, ecosystem management as a measure of mink control appears to be ineffective.

Estimating the density of wildlife populations is still a difficult task, especially when you work with spatially open populations and you must relax the assumption of closure, which is the basis of most methods currently used. Further difficulties arise when obtaining density estimates at small spatial scales. Using eight years (1996-2003) to monitor data from a roe deer Capreolus capreolus population that lives in a sub-Mediterranean environment in central Italy, we were able to estimate local density (at a spatial scale of one home range) by using a large sample of radio-marked animals. Local density estimates could be obtained only in zones in which radio-marked deer were available in sufficient numbers. To estimate local density in the whole study area, we developed a calibration model, which allowed us to infer density where radio-marked deer were absent or scarce. To do this, we computed the mark-resight density estimates (using radio-marked animals) and related these estimates to linear and non-linear functions of animal count and surface area of fields, to obtain a set of density estimators. Then, we selected a linear combination of such estimators, whose quality was assessed by cross-validation. Our results show that the method we propose can be effective in investigating small-scale spatial structure of density in a roe deer population. We see several potential applications of this method for both research and management purposes.

Helicopters are used for numerous wildlife management and research purposes, but can alter wildlife behaviour and influence baseline data collection. We investigated reactions of GPS-collared moose Alces alces and brown bears Ursus arctos to short-term helicopter approaches by researchers. Moose responded with up to 10 times greater movement rates for up to two hours following a helicopter approach and moved into more rugged terrain. Brown bears decreased their speed and remained within similar habitat types and terrain. The movements were influenced only about two hours and did not influence the size of the activity areas. Contrary to our predictions, brown bears responded with a somewhat calmer response than moose, illustrating response differences in large herbivores and carnivores. This difference in response might be because brown bears are actually less disturbed than moose by direct helicopter approaches or because of a difference in tactical behaviour between brown bears and moose following disturbance. Researchers and managers should thus be cautious in using knowledge from one species to predict or perceive disturbance response in another species or taxa.

In much of northern Sweden moose Alces alces browse rowan Sorbus aucuparia heavily and commonly revisit previously browsed plants. Repeated browsing of rowan by moose has created some concern for its long-term survival in heavily browsed areas. We therefore measured how four years of simulated moose browsing at four population densities (0, 10, 30 and 50 moose/1,000 ha) changed plant height, crown width, available bite mass, the number of bites per plant and per plant forage biomass of rowan saplings. Increased biomass removal led to a significant decline in plant height (P < 0.001), but a significant increase in the number of bites per plant (P = 0.012). Increases in the number of bites per plant more than compensated for weak decreases in bite mass, leading to a weak increase in per plant forage biomass (P = 0.072). With the decline in plant height and increase in the number of stems per plant, a greater number of bites remain within the height reach of moose relative to unbrowsed controls. Moose therefore stand to benefit from revisiting previously browsed plants, which may result in feeding loops between moose and previously browsed rowan saplings.

In this study we present empirical data on predator numbers, movements and area usage, and predation obtained from tracking transient killer whales Orcinus orca throughout the inland waters of southeastern Alaska, USA. During 1991-2007, we documented 155 transient killer whales via photo-identification methodology within the large study area (27,808 km²). Transient killer whales were distributed throughout southeastern Alaska and were present during all seasons, although not all individuals were seen every year. Resighting data suggested that within southeastern Alaska, maternal groups may partition area usage of their environment. By following whales for 1,467 km, we calculated a mean travel speed of 7.2 km/hour with mean daily movements of 134 km ± 88 km/24 hours and ranging within 59-240 km/24 hours. Photographic matches demonstrated that most of the transient killer whales (86%) identified in southeastern Alaska also utilized British Columbia and Washington State waters. In contrast, photographic matches between whales in southeastern Alaska and whales seen off of California, USA, were rare, suggesting that different transient killer whale stocks occupy these two regions. Transient killer whales preyed upon Dall's porpoise Phocoenoides dalli, Pacific white-sided dolphins Lagenoryhncus obliquidens, harbor porpoise Phocoena phocoena, minke whales Balaenoptera acutorostrata, Steller sea lions Eumetopias jubatus, harbor seals Phoca vitulina and seabirds. Potential prey species that were available, but not targeted, included humpback whales Megaptera novaeangliae, elephant seals Mirounga angustirostris and sea otters Enhydra lutris. Prey-handling techniques varied depending on the prey being targeted with no evidence of prey specialization. During 114 encounters totaling 332.5 hours of direct observations of transient killer whales, we documented 36 predation events for a calculated kill rate of 0.62 prey items/24-hour period/whale. The data we present in this article provide a foundation of transient killer whale ecology aimed at improving our ability to understand the impact of transient killer whale predation on southeastern Alaska prey populations.

Free-ranging African elephants Loxodonta africana use their front feet frequently during the process of foraging and this could be the reason for the high prevalence of physical injuries to these parts of the body. Although the occurrence of severe lameness caused by foot lesions in adult elephants has already been investigated and the clinical and pathological findings have been reported, the effect of foot injuries on glucocorticoid levels as a potential physiological stress response has not been examined. Given the practical difficulties involved in monitoring unpredictable events in free-ranging animals, like the occurrence of foot injuries in elephants, it is not surprising that information regarding the endocrine correlates of physical injury is still limited for elephants. In our study we investigated the effects of foot injuries on concentrations of faecal glucocorticoid metabolites (GCM), body condition score (BCS) and reproductive behaviour in two GPS/radio-collared elephant bulls in the Kruger National Park, South Africa. We monitored the bulls aged 40 (Bull 1) and 30 (Bull 2) 2-3 times per week for 13 months starting in June 2007 and frequently collected faecal samples for non-invasive hormone monitoring. Faecal samples were lyophilised, extracted and assayed with an enzyme immunoassay which detects GCM with a 3α-hydroxy-11-oxo-structure. Both bulls acquired foot injuries (right-front), which caused temporary lameness, but the effect of injury on GCM concentration differed between bulls (P < 0.001). In Bull 1 the injury lasted ± 250 days and was associated with an up to four-fold increase in GCM concentrations (P < 0.001) and his BCS reduced from ‘good‘ to ‘very thin‘ by the end of the injury period. In Bull 2 the injury lasted 65 days and was associated with a smaller increase in GCM concentrations (P = 0.03) together with a reduced loss in condition when compared to Bull 1. Following recovery, the condition of both bulls improved progressively and faecal GCM returned to baseline concentrations. Collectively, the data clearly underlined the value of non-invasive hormone measurements as a tool to provide information on the level of stress experienced by elephants. Thus, monitoring GCM levels could help improve the assessment of an elephant's state of health.

Yellowstone bison Bison bison are chronically infected with brucellosis (caused by the bacterium Brucella abortus), which raises concerns about possible transmission to cattle when they migrate to winter ranges outside the Yellowstone National Park. We monitored bison from April to mid-June during 2004-2007 to estimate the timing and location of parturition events that may shed tissues infected by B. abortus. Observed abortions (N = 29) occurred from January through 19 May, while peak calving (80% of births) occurred from 25 April to 26 May, and calving was finished by 5 June. Observed parturition events (N = 115) occurred in the Park and on the Horse Butte peninsula in Montana, USA, where cattle were not present at any time of the year. Allowing bison to occupy public lands outside the Park where cattle are never present (e.g. Horse Butte peninsula) until most bison calving is completed (late May or early June) is not expected to significantly increase the risk of brucellosis transmission from bison to cattle because: 1) bison parturition is essentially completed weeks before cattle occupy nearby ranges, 2) female bison meticulously consume birthing tissues, 3) ultraviolet light and heat degrade B. abortus on tissues, vegetation and soil, 4) scavengers remove fetuses and remaining birth tissues and 5) management maintains separation between bison and cattle on nearby ranges. Allowing bison to occupy public lands outside the Park through their calving season will help conserve bison migratory behaviour and reduce stress on pregnant females and their newborn calves, while still minimizing the risk of brucellosis transmission to cattle.