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Frequency of studies reporting various anthropogenic, environmental and non-specific causes for entry of wildlife into care, and mortality post-release
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Millions of native animals around the world are rescued and rehabilitated each year by wildlife rehabilitators. Triage and rehabilitation protocols need to be robust and evidence-based, with outcomes consistently recorded, to promote animal welfare and better understand predictors of wildlife survival. We conducted a global systematic review and me...
Citations
... Wildlife rescue, rehabilitation, and release (hereafter wildlife rescue) is a global practice that impacts hundreds of thousands (Pyke and Szabo 2018) to potentially millions of wild animals annually (Cope et al. 2022), with implications for both conservation (Pyke and Szabo 2018;Simeone et al. 2024) and animal welfare (Mullineaux 2014;Willette et al. 2023). While both the number of animals rescued and the volume of scientific literature on wildlife rescue are increasing each year, previous studies have noted a lack of methodological rigour and reporting quality in the literature (Mullineaux 2014;Pyke and Szabo 2018;Cope et al. 2022;Simeone et al. 2024). ...
... Wildlife rescue, rehabilitation, and release (hereafter wildlife rescue) is a global practice that impacts hundreds of thousands (Pyke and Szabo 2018) to potentially millions of wild animals annually (Cope et al. 2022), with implications for both conservation (Pyke and Szabo 2018;Simeone et al. 2024) and animal welfare (Mullineaux 2014;Willette et al. 2023). While both the number of animals rescued and the volume of scientific literature on wildlife rescue are increasing each year, previous studies have noted a lack of methodological rigour and reporting quality in the literature (Mullineaux 2014;Pyke and Szabo 2018;Cope et al. 2022;Simeone et al. 2024). However, no studies have systematically quantified these shortcomings. ...
... Many wildlife enter the rescue system due to human-related causes (e.g. vehicular collision) (Adhikari et al. 2022) and, of the minority that survive to release, post-release outcomes are often poor (Cope et al. 2022). Improving the practice of wildlife rescue could generate population-level conservation benefits, including for threatened species such as the Little Brown Bat (Myotis lucifugus) (Paterson et al. 2021). ...
Wildlife rescue, rehabilitation, and release is a global practice with a broad body of scientific literature; nonetheless, no studies have assessed and quantified the methodological rigour and reporting quality of this literature. In this PRISMA systematic review, we assessed and quantified the reporting of controls, randomisation, blinding, experimental animal data, and housing and husbandry data in 152 primary studies on wildlife rescue, rehabilitation, and release published between 1980 and 2021. We then tested for associations between reporting and study characteristics. Of the 152 reviewed studies, one study reported a control, randomisation, and blinding; 17 studies reported species, age, sex, weight, and body condition; and 14 studies reported housing size, housing location, type of food, provision of water, and provision of enrichment. No study reported all 13 of these elements. Studies published in veterinary-focused journals reported lower methodological rigour and had lower reporting quality than studies published in other types of journals. Studies on mammals had higher reporting quality than studies on birds and on reptiles, and studies that included the word “welfare” had higher reporting quality than studies that did not. The overall low methodological rigour and reporting quality of the literature limits study replicability and applicability and impedes meta-analyses.
... The release of rehabilitated wildlife holds potential for conservation efforts, evidenced by management and research (Cope et al., 2022). However, most studies have focused on individual survival and recovery, neglecting the potential population-level contributions (Paterson et al., 2021) and impact of released animals (Mitman et al., 2021) in the wild. ...
Asiatic black bears (Ursus thibetanus) are threatened by habitat loss and fragmentation, illegal hunting, and human-wildlife conflict. Effective conservation depends on robust population assessment and understanding habitat use. This study investigated the distribution and environmental drivers of Asiatic black bear occupancy within Pakke Tiger Reserve (PTR), Arunachal Pradesh, India, using non-invasive methods. A grid-based sampling design was implemented, surveying 315 (62%) of PTR's 511 grid cells using camera trapping (140 cameras) and sign surveys (478 km of trails). Estimates of the best model revealed detectability at (p=0.43; SE=0.014) and occupancy at (psi=0.58; SE=0.110). Multi-model inference identified Terrain Ruggedness Index (TRI), Enhanced Vegetation Index (EVI), and termite mound availability (TMA) as key occupancy predictors. Bears preferred less rugged terrain (negative association with TRI, estimate = -0.08), areas of higher vegetation productivity (positive association with EVI, estimate = 0.36), and areas with abundant termite mounds (positive association with TMA, estimate = 4.76). A weak negative association with road proximity (PXR, estimate = -0.05) suggested some avoidance of human trails. Detection probability was positively correlated with survey effort (EFF, estimate = 1.19). The estimated overall encounter rate was 2.38/trap night, and the estimated occupancy rate was 58%, indicating a wider distribution than suggested by naive occupancy. These findings provide crucial baseline data for evaluating PTR's effectiveness in bear conservation and inform management strategies, including ongoing bear rehabilitation efforts at the Center For Bear Rehabilitation and Conservation (CBRC). This study emphasizes the importance of considering multiple environmental factors and rigorous survey design for understanding and managing bear populations in complex landscapes, highlighting the need for continued monitoring and research to ensure the long-term conservation of Asiatic black bears in this region, and in other landscapes where similar conditions prevail.
... Wildlife rehabilitation and release occurs for many species, with many injuries and illnesses (Cope et al. 2022). Significant time, labour, cost and emotional investment goes into the rescue, treatment, rehabilitation and release of animals. ...
... Survival of rehabilitated wildlife is both individual and species-specific, including bodyweight, age, sex, as well as the conditions associated with the return habitat (e.g. species breeding season, weather) (Cope et al. 2022). The prognosis of these animals is largely unknown as few cases are monitored post-release. ...
The success of rehabilitated juvenile animals after release is poorly studied. This study monitored the behaviour and habitat use of a juvenile male platypus (Ornithorhynchus anatinus) found in poor body condition on a driveway and rehabilitated, before undergoing an inter-catchment translocation. Radio telemetry tracked his movements and resting locations for 18 days during which he used more vegetation for shelter than burrows. After 8 days in the creek near the release site, he travelled through drains into a swamp, potentially displaced by resident platypuses, where the signal was lost. The results demonstrate significant challenges in post-release survival, including burrow creation. This case highlights the importance of monitoring animals after release.
... Release rates risk overestimating successful rehabilitation by failing to account for short-term postrelease mortality; therefore, this study also assessed 28-d survival as a secondary outcome measure. 8 Herein, the 28-d survival rate was lower than the release rate. This may reflect immediate postrelease mortality in a number of pangolins being released before 28 d; however, survival rate is also influenced by the fact not all pangolins were monitored postrelease. ...
The establishment of prognostic indicators in wildlife patients aids clinical decision-making and resource allocation. Hematological and plasma biochemical parameters were evaluated as potential prognostic indicators in wild Temminck’s pangolins (Smutsia temminckii) rescued from the illegal wildlife trade. In this prospective cohort study, EDTA and lithium heparin blood samples were collected from the ventral coccygeal vein in 41 pangolins within 48 h of confiscation and before veterinary intervention. Receiving operator characteristic curve analysis was performed to assess each parameter as a prognostic indicator for release outcome and, where known, for 28 d survival postadmission. RBC counts, hemoglobin concentration, and Hct were significantly lower in female than in male pangolins. On intake, pangolins that later failed to be released had significantly lower mean corpuscular hemoglobin concentration (MCHC), higher blood urea nitrogen (BUN), and higher creatinine (Crea) values than individuals that were released. Individuals with lower MCHC or higher Crea values were also less likely to achieve 28-d survival. No pangolin with MCHC < 30.2 g/dl, BUN > 84 mg/dl, or Crea > 0.8 mg/dl was successfully rehabilitated. No other hematological or biochemical parameter, including plasma cortisol, total protein, lactate, lactate dehydrogenase, and glucose, showed significant prognostic value. This study suggests that MCHC, BUN, and Crea measured on intake are useful prognostic indicators for rehabilitation success and MCHC and Crea for short-term survival in Temminck’s pangolins.
... It is necessary to collect data on survival, reproduction, and dispersal. Collaborative efforts among researchers, rescue station staff, field ornithologists, and conservation organizations can significantly reduce the major constraints on postrelease monitoring, such as lack of funding or expertise, software availability, and data processing time (Cope et al. 2022). We encourage the continuation of detailed species-specific post-release studies, particularly in relation to choice of treatment and rehabilitation methods and subsequent survival outcomes. ...
There are many raptor rehabilitation centers around the world that receive and care for wild raptors. Wildlife rehabilitation is a labor- and cost-intensive part of addressing animal welfare. Apart from the compassionate aspect of taking responsibility for an injured animal, there remains an open question as to whether doing so contributes to animal conservation. The fates of such animals after their rehabilitation and release have rarely been studied. Long-term post-release monitoring is needed to assess survival and reproduction. Here, we investigate the post-release fates of 22 White-tailed Eagles (Haliaeetus albicilla), including juveniles, immature birds, and adults in Austria, the Czech Republic, Germany, and Slovakia. Using GPS tracking, we monitored the eagles for 2–2639 d (median = 340 d) between 2005 and 2023. The longest-surviving eagle was tracked for more than 7 yr. Release was followed by a short 6-d period of high mortality, followed in turn by a long-term annual adult survival rate of 74.6%. Anthropogenic factors contributed to 70% of the long-term mortality cases. Reason for admission, length of hospital stay, and use of flight aviaries had no statistically significant effect on long-term survival. Five eagles successfully bred and produced a total of 10 fledglings. Traveling as much as 1378 km, the released eagles dispersed throughout central, northern, and eastern Europe. Thus, it can be concluded that successful rehabilitation of White-tailed Eagles resulted in high survival rates; and in five cases, successful reproduction indicated effective reintegration into the wild population.
... Rescuing and rehabilitating wildlife can be stressful for animals [139], and the risks to animal welfare need to be weighed against the potential benefits for both the individual and the population [24]. Some species have a low survival rate after release following rehabilitation [11], while other species reintegrate back into the wild with minimal expense to fitness [95]. ...
Background
Wildfires can have complex effects on wildlife populations. Understanding how post-fire conditions affect the movement ecology of threatened species can assist in better conservation and management, including informing the release of rescued and rehabilitated animals. The 2019–2020 megafires in Australia resulted in thousands of animals coming into care due to injury or concerns over habitat degradation. This included hundreds of koalas (Phascolarctos cinereus), for which relatively little was known about how fire affected habitat suitability, or when rehabilitated animals could be returned to burnt areas.
Methods
We compared the movements of koalas across three experimental groups–non-rehabilitated koalas in burnt habitat, non-rehabilitated koalas in nearby unburnt habitat, and rehabilitated koalas returned to their rescue location in burnt habitat in New South Wales, Australia. We GPS-tracked 32 koalas for up to nine months and compared, across treatment groups, home ranges, mean nightly distance moved, the farthest distance moved from their release site and total displacement distance.
Results
We found no differences in koala movements and home range size between non-rehabilitated koalas in burnt and unburnt habitat. However, rehabilitated koalas moved farther from their release site, had larger displacement distances, and larger home ranges than non-rehabilitated individuals. Regardless of their experimental group, we also found that males moved further than females each night. Additionally, our resource selection analysis showed that, koalas preferred low and moderately burnt habitats over all other fire severity classes.
Conclusions
Experimental frameworks that incorporate “treatment” and “control” groups can help isolate disturbance effects on animal movements. Encouragingly, despite catastrophic wildfires, burnt woodlands provided adequate resources for koalas to persist and recover. Furthermore, rehabilitated koalas re-integrated into the burnt landscape despite moving farther from their release sites than non-rehabilitated individuals. Studies like this improve our understanding of the ecological impacts of fire on species and their habitats, and will be instrumental in informing wildlife management and conservation efforts as wildfires increase in frequency and severity worldwide in response to climate change.
... Concerns exist about conditioning animals to human interaction during rehabilitation, which may lead to post-release con icts. However, this habituation can be prevented by assigning one or two speci c caretakers and employing pre-release training, which is a common practice in soft release procedures [13][14][15]. ...
... During the rehabilitation period, bears may develop habituation to humans or anthropogenic environments, which can reduce their survival after release [14,21,22]. Therefore, pre-release training is recommended to restore threat avoidance behavior and natural food recognition [14,15]. ...
... During the rehabilitation period, bears may develop habituation to humans or anthropogenic environments, which can reduce their survival after release [14,21,22]. Therefore, pre-release training is recommended to restore threat avoidance behavior and natural food recognition [14,15]. To mitigate the risk of habituation to humans, we limited human interaction to one or two caretakers and conducted pre-release tests to ensure that avoidance behaviors were maintained. ...
Background Wildlife rehabilitation is crucial for the recovery of injured endangered species; however, this process can induce significant stress, potentially leading to secondary injuries and complications. This case report details the rehabilitation of two severely injured Formosan black bears ( Ursus thibetanus formosanus ) with desensitization techniques as an alternative approach to reducing stress while promoting voluntary cooperation during treatment. Case presentation Patient 1 was an adult female bear with injuries, including the loss of the second, third and fourth phalanges of the left forelimb and extensive necrosis of the right palm. Patient 2 was a subadult male suffering from multiple gunshot wounds, severe necrosis of the distal part of the right wrist, and a fracture of the right mandibular ramus and left humerus. Both bears underwent desensitization training, which fostered calmness during routine procedures and facilitated smooth recovery throughout rehabilitation. Pre-release training focused on rebuilding physical capacity and developing natural behaviors, as well as human avoidance, to increase survival and reduce human-bear conflicts. Conclusions The successful outcomes, characterized by complete recovery and avoidance of human interactions, underscore the effectiveness of desensitization strategies in wildlife rehabilitation. This approach not only enhances the quality of medical care but also mitigates the risks of post-release conflicts, contributing to the conservation of endangered species.
... Data were collected using mixed methods, including a literature review, interviews, and field observations at each stage of rehabilitation and release of Javan hawk-eagle (Noga et al. 2018). This study collected data on all the criteria and indicators of success at each stage of rehabilitation and release, with a particular focus on the health and behavioral aspects (Cope et al. 2022). The compilation of Rehabilitation Criteria and Indicators for the Successful Release of Javan Hawk-eagle (RCISRJHE) used a research model developed from the Borg and Gall model (Maydiantoro 2021). ...
Munawir A, Mardiastuti A, Masy’ud B, Prawiradilaga DM. 2024. Rehabilitation criteria and indicators for the successful release of Javan hawk-eagle (Nisaetus bartelsi Stresemann, 1924). Biodiversitas 25: 3491-3499. The Javan hawk-eagle (Nisaetus bartelsi Stresemann, 1924) is an endangered bird of prey that is native to Java Island and is protected by law. In order to save the species, rehabilitation programs are crucial for increasing its population in the wild. The current research aimed to establish criteria and indicators for rehabilitating Javan hawk-eagles and improving their chances of a successful release. Data were collected from literature review, interviews, and field observation. Collected data were scored based on a Likert scale and weighted on selected criteria and indicators, then described qualitatively. The research resulted in the identification of 34 criteria and 152 indicators. There were several rehabilitation stages observed in this research: 1) acceptance stage with 10 criteria and 30 indicators; 2) isolation stage with as many as six criteria and 18 indicators; 3) treatment stage with as many as four criteria and 12 indicators; 4) pre-training stage with as many as five criteria and 15 indicators, 5) training stage with five criteria and 65 indicators, and 6) habituation stage with four criteria and 15 indicators. The testing of 12 Javan hawk-eagle individuals at the Javan Hawk-eagle Sanctuary Center (JHESC), along with the developed criteria and indicators, could be feasible for rehabilitation standards to release Javan hawk-eagles successfully. According to the decision tree, nine out of the 12 individuals went through four stages, one went through three stages, and two went through two stages. In summary, the criteria and indicators have increased potential numbers and accelerated the rehabilitation process for the success of Javan hawk-eagle release.
... Unfortunately, the injuries are usually caused by direct or indirect anthropogenic activities such as gunshot wounds and collisions into cars, buildings, windows, or power lines [1][2][3][4][5][6][7][8][9][10]. These injuries usually require treatment with analgesics and anti-inflammatory medications to control pain and inflammation [11][12][13]; however, there is limited evidence-based research available characterizing the pharmacokinetic or pharmacodynamic properties of these drugs for raptors. ...
Anthropogenic activities have negatively affected many birds, including owls. The Wildlife Hospital of Louisiana (WHL) has seen a 3.2-fold increase in barred owl (Strix varia) cases over the past eight years (2023, 134; 2015, 42). Because most of these animals present with traumatic injuries, analgesics should be considered in their treatment plan. To date, no study has measured the pharmacokinetics of an analgesic in barred owls. The goals of this study were to determine the harmonic means, times to maximum concentration, and elimination half-lives for single 1 mg/kg and 2 mg/kg intramuscular doses of meloxicam. Twelve barred owls (1 mg/kg, n = 6; 2 mg/kg, n = 6) admitted to the WHL and determined to be clinically normal based on examination and blood work were recruited for this study. Meloxicam was administered intramuscularly, and blood samples were collected intermittently over 12 h to measure plasma concentrations using high-performance liquid chromatography. Both doses had rapid elimination half-lives (1 mg/kg, 0.99 ± 0.1 h; 2 mg/kg, 1.07 ± 0.43 h) and were below the limits of quantification (0.1 µg/mL) by 6–12 h. Based on these results, 1 and 2 mg/kg doses of meloxicam were found to produce plasma concentrations below therapeutic concentrations for less than four hours, making current twice-daily recommended dosing intervals unlikely to provide desired analgesia.
... The treatment of injured wild animals to return them to their natural habitat is of pivotal importance in wildlife recovery centers worldwide. Birds are usually the most affected group of autochthonous species admitted to recovery centers, followed by mammals and, Birds 2024, 5 638 to a much lesser extent, reptiles and amphibians [1,2]. Birds are heavily reliant on their visual sense [3]. ...
... The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/birds5040043/s1, Table S1: Relationship between ocular lesions and main admittance causes (trauma and unknown categories) (X 2 (1) test). Each subscript letter denotes a subset of cause of admittance categories for which column proportions do not differ significantly from each other at a significant level of 0.05. . ...
In wildlife rehabilitation centers, thousands of animals are treated annually, with a substantial proportion being birds of prey. Since vision is essential for the survival of these species, this study focused on investigating the causes of ocular injuries in raptors admitted to four rehabilitation centers across mainland Portugal from 2017 to 2021. Of the 2207 birds admitted during this period, 156 (7%) presented ocular injuries. Hyphema (28.2%) and corneal ulcers (20.5%) were the most prevalent injuries, often occurring together or alongside lens luxation. Nocturnal raptors showed a higher prevalence of these injuries (76.9%) compared to diurnal raptors (23.1%). A significant association was found between ocular injuries and causes of admission, particularly with ocular hemorrhages and multiple injuries in the eye. Despite the severity of the ocular injuries, the release rate remained relatively high at 51%, underscoring the critical role of comprehensive ocular examinations and vision assessments in guiding treatment decisions and discharge decisions. This study highlights the need for further research with larger samples to better understand the impact of ocular injuries on the rehabilitation success of wild birds in Portugal.
