Captive husbandry and veterinary care of northern New Zealand dotterels (Charadrius obscurus aquilonius) during the CV Rena oil-spill response

Abstract

Context Oil spills cause significant detrimental impacts on many shoreline species. There is limited information in the scientific literature about the management and response of shorebirds to oil spills. Northern New Zealand dotterels (Charadrius obscurus aquilonius) were pre-emptively captured as part of the oiled wildlife response to the container vessel Rena oil spill, to ensure the survival of a regional population should there be a catastrophic release of oil. Previous attempts to hold dotterels in captivity have resulted in high mortality. Aims To describe the captive husbandry and veterinary management of wild-caught adult dotterels, to outline the common problems encountered, and make recommendations for future captive management. Methods The dotterels were caught by noose mat on beaches at risk of further contamination by oil. Initially, dotterels were kept individually indoors and force-fed until they converted to self-feeding on a diet of an artificial insect analogue, ox heart and mealworms. Once self-feeding, the birds were shifted to individual outdoor aviaries. Key results Sixty dotterels were caught. About half of birds had oil contamination of the legs, nine birds had light oil staining of feathers and only three of these birds required washing. The degree of oiling and washing did not affect survival. Dotterels took a median of 5 days (range 1–15 days) to convert to the captive diet. Common problems encountered in captivity included carpal and beak abrasions (61.7%) and pododermatitis (75%); however, these did not affect survival. Seven birds (11.7%) developed respiratory disease and six of these died from aspergillosis. The incidence of aspergillosis increased with length of time in captivity and was largely refractory to treatment. The 54 surviving birds were released at their capture sites after a median time of 49 days in captivity (with a range of 39–61 days). Conclusions The captive management of the dotterels achieved a 90% survival rate over a period of about 2 months. Deaths were solely due to respiratory aspergillosis, but intensive captive husbandry was required to convert the birds to a captive diet, to minimise traumatic injuries and to manage pododermatitis. Implications Although the captive management of shorebird species as a pre-emptive strategy to minimise the effects of oil spills carries significant costs and risks to the birds, it should be considered in the emergency management of high-priority species.