Over the last ten years, zoos and aquariums around the world have been coming to grips with the "sustainability crisis"the realization that most of our collaboratively managed animal populations are not viable for the long-term. Many initiatives have been launched at the regional, zoological association, program, and institutional levels to improve the long-term trajectories of these populations. This Special Issue of Zoo Biology highlights some of the scientific approaches that are aimed at addressing population viability and sustainability challenges. The approaches range from development of new analytical tools, to analysis of large datasets, and re-examination of population management principles and philosophies. While much progress has been made in the last ten years, it is clear that continued work on population viability and sustainability is critical and difficult management decisions must be made. In this paper, we identify some of the actions that the zoological community can take to fortify our animal programs and prevent the outright extinction of species. K E Y W O R D Sbreeding program, population, sustainability, viability

Ulcerative lesions are a health concern for managed black rhinoceros (Diceros bicornis) populations. To examine possible relationships between ex situ variables and adrenal activity with the presence of lesions, facility and socioenvironmental surveys of 25:20 (male:female) black rhinos at 18 zoos were conducted, and fecal samples were collected twice weekly for 1 yr for glucocorticoid metabolite analyses. During the collection period, 5.1 rhinos exhibited skin lesions, 1.0 had oral lesions, and 1.0 had both. All of the rhinos with lesions recovered, except the one with both oral and skin lesions, which died shortly after the end of the study. In general, there were no relationships (P > 0.05) between ex situ variables, or rhino behavior indices, and lesion onset. There also were no differences (P > 0.05) in fecal glucocorticoid variability (+/- SEM) between rhinos with (coefficients of variation [CV] = 57.1 +/- 7.2 ng/g) and without (53.8 +/- 2.3 ng/g) lesions, or in overall mean (+/- SEM) glucocorticoid metabolite concentrations between rhinos with (45.1 +/- 4.0 ng/g) and without (34.6 +/- 2.8 ng/g) lesions. However, baseline mean (+/- SEM) glucocorticoid metabolite concentrations were lower (P < 0.05) in rhinos with lesions (n = 5.1, baseline mean = 29.9 +/- 3.3 ng/g, range: 24.3-84.9 ng/g) than without (n = 19.19 baseline mean = 40.0 +/- 2.4 ng/g, range: 19.4-50.8 ng/g). For a male rhino that developed lesions during the study, the mean glucocorticoid concentrations were lower (P < 0.01) when lesions were present (n = 12, overall = 30.1 +/- 2.4 ng/g, baseline = 28.7 +/- 2.2 ng/g) than prior to lesion onset (n = 75, overall = 36.5 +/- 1.0 ng/g, baseline 35.3 +/- 0.8 ng/g). These results suggest that ulcerative lesions may be associated with changes in adrenal activity, although it is not clear if this is a cause or effect of disease.

Zoos and aquariums accredited by the Association of Zoos and Aquariums (AZA) cooperatively manage Species Survival Plan (R) (SSP) Program populations to maximize genetic and demographic health and work toward long-term population sustainability.However, recent analyses suggest that only a minority of populations were projected to maintain their sustainability goals over 100 years. As one of the initial steps in addressing this concern, the AZA collaborated with hundreds of members of the zoo and aquarium community to develop the SSP Sustainability Database, a repository of quantitative and qualitative data on SSP Program challenges, population data, and management needs. A goal of this initiative was to identify the most critical needs across taxa and provide AZA-accredited facilities a mechanism to align institutional resources with SSP Program priorities, thus facilitating strategic decision-making for population sustainability at all levels of population management. Four types of critical SSP population needs emerged as the most common: additional spaces, optimized and standardized husbandry practices, the incorporation of new individuals into the population (importation), and improved breeding and transfer recommendation fulfillment. Patterns and trends in these critical needs varied across taxa and ex situ extinction risk (proxied by population management designation). The AZA community can apply these findings and proactively engage in opportunities to enhance SSP Program population sustainability through strategic, collaborative group action. K E Y W O R D Spopulation health, population management, SSP program, sustainability

Ulcerative oral and skin lesions have become an issue of concern for the health of the managed black rhinoceros (rhino) (Diceros bicornis) populations. Lesions exhibited by the black rhino are clinically similar to those observed in other species with superficial necrolytic dermatitis (SND). One biochemical alteration in dogs with SND is severe hypoaminoacidemia, and nearly all cases are fatal. The objective of this study was to determine if black rhinos with analogous lesions exhibit a similar hypoaminoacidemia. Amino acid concentrations were measured in monthly plasma samples collected for 1 yr from black rhinos with (n = 4) and without (n = 34) lesions clinically consistent with SND. The rhinos with skin and/or oral lesions were zoo born males, ages 2, 6, 17, and 23 yr, from four different facilities. Three rhinos recovered from skin (n = 2) and oral lesions (n = 1). However, the one male with both skin and oral lesions died with the disease. None of the affected black rhinos exhibited a decrease in any of the amino acids evaluated or for total amino acid concentrations (P > 0.05). Based on the absence of hypoaminoacidemia and the comparatively low mortality rate in rhinos with lesions, it appears that this syndrome is not entirely consistent with SND observed in other species. These data will be useful for future assessments of rhino nutritional status and other potential metabolic diseases.

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