Identifying the Stressors Impacting Rescued Avian Wildlife

Abstract

Urbanisation exposes avian wildlife to an array of environmental stressors that result in clinical admission and hospitalisation. The aim of this pilot study was to conduct a retrospective analysis of clinical data and characterise this based on categories of stress experienced by avian wildlife patients. The results from this study indicated that impact injuries (n = 33, 25%) and vehicle-related injuries (n = 33, 25%) were the most common occurring preliminary stressors that resulted in the hospitalisation of avian wildlife. The most common outcome of avian patients that suffered from vehicle-related injuries was euthanasia (n = 15, 45%), as was avian patients that suffered from impact injuries (n = 16, 48%). Immobility (n = 105, 61%) and abnormal behaviour (n = 24, 14%) were the most commonly occurring primary stressors of avian patients. Finally, trauma (n = 51, 32%) and fractures (n = 44, 27%) were the most common occurring secondary stressors in avian patients. The most common outcome of all these stressors was euthanasia. This study provided further evidence towards the notion that human- and urbanisation-related stressors are the main causes of hospitalisation of avian wildlife, but also indicated that birds admitted as a result of human-related stressors are more likely to be euthanised than released. This study also provided a categorisation system for the stressors identified in avian wildlife patients (preliminary, primary and secondary) that may be used to monitor the stress categories of wildlife patients and gain a deeper understanding of the complex notion of stress.

Evaluating the Stressors Impacting Rescued Reptilian Wildlife

“…The datasheet for each individual included the location from which it was rescued and was included in the database provided. On the basis of information provided by Australia Bureau of Statistics and method outlined in [12,35], the rescue location was used to classify all rescued individuals in four habitat categories, namely-rural, urban, suburban and unknown. We used the Google Earth program to input rescue location to obtain a satellite view for categorising the individuals.…”

“…The database of rescued wildlife included the cause of presenting the animal to the clinic and the clinical diagnosis for each individual. As inferred from Schreck et al [36] and Janssen et al [12], these records were classified into four stressor categories (resulting in respective stress levels) as preliminary stressors (P1S), primary stressors (P2S), secondary stressors (SS) and tertiary stressors (TS). P1S included any external stimulus that had the potential and/or led to any form of physical (including but not limited to vehicle collisions and animal induced trauma), physiological (including but not limited to feed and water deprivation and extreme temperatures) and/or psychological stress (including but not limited to confinement and/inappropriate environments and surroundings) resulting in admission of the individual to the hospital [12,36].…”

“…As inferred from Schreck et al [36] and Janssen et al [12], these records were classified into four stressor categories (resulting in respective stress levels) as preliminary stressors (P1S), primary stressors (P2S), secondary stressors (SS) and tertiary stressors (TS). P1S included any external stimulus that had the potential and/or led to any form of physical (including but not limited to vehicle collisions and animal induced trauma), physiological (including but not limited to feed and water deprivation and extreme temperatures) and/or psychological stress (including but not limited to confinement and/inappropriate environments and surroundings) resulting in admission of the individual to the hospital [12,36]. P2S included any external stimulus that induced, or were potentially capable of inducing a primary stress response causing an increase in catecholamine and steroid hormones (including but not limited to complete/partial immobility, temporary abnormal behaviour, bleeding, laceration and abrasion) [12,36,37].…”

“…The contribution of ever increasing urbanisation and population growth rates, in driving wildlife populations towards extinction is also well explored within the literature [9][10][11]. The activities associated with urbanisation and population growth result in habitat loss and fragmentation, thus, indirectly exposing wildlife to various biotic and abiotic environmental stressors [3,12]. Almost all retrospective studies identify both, direct and indirect extrinsic stressors that result in wildlife being admitted to wildlife clinics.…”

“…Wildlife rescue databases serve as an important tool in the field of ecological research to explain the negative impacts of anthropogenic activities on wildlife and to improve urban planning by taking appropriate measures to ameliorate the negative consequences of such activities [22]. Furthermore, categorizing direct and indirect anthropomorphic perturbations based on stressor categories at an individual level can help in understanding the synergistic impact of stressors on an individual and thereby assist in minimising the intensity of stressors during rescue; treatment; throughout rehabilitation and during release [12]. For example, a lizard kept as an illegal pet might seem physically healthy and ready for release in the wild, but may be exposed to preliminary stressor in the form of inappropriate housing conditions as a result of which it might exhibit a primary stress response in the form of temporary abnormal behaviour.…”