There is a need to develop appropriate monitoring methods for cryptic reptile species, such as the endangered New Zealand endemic Otago skink (Oligosoma otagense), that take into account incomplete detectability. A recently developed analytical technique was applied to presence–absence data for Otago skinks to derive robust estimates of both detection probability and site occupancy. The estimated detection probability for Otago skinks was 0.4 (s.e. 0.052), and the estimate of the proportion of the study area occupied by Otago skinks was 0.71 (s.e. 0.11). The data derived from presence–absence surveys in consistently sunny weather, with a standardised scanning and searching technique, provided a good basis for robust estimates of detection probability and of the percentage of area occupied by skinks. This survey technique could be applied to other similarly cryptic reptile species to derive rigorous estimates of site occupancy in order to track changes over time or in response to management interventions. It will be particularly appropriate where precise estimation of absolute abundance is not warranted, or where a simple index of relative abundance may be invalid due to failure of the implicit assumption of constant detectability.
Context. The process of urban sprawl brings the human population and their domestic cats (Felis catus) in close contact with wildlife in areas that were previously remote, including reserves and conservation areas created to protect populations of vulnerable or threatened species. Various mitigation measures have been proposed, including devices designed to hinder cat hunting ability, desexing to reduce wandering and nuisance behaviours, containment at night or at all times and regulations governing cat ownership. Such regulations may aim to reduce cat densities by limiting the number of cats per household, or they may define zones around sensitive conservation areas where cat ownership is prohibited. Aims. The present study sought to establish the necessary size of cat-exclusion zones in rural and urban-fringe landscapes where vulnerable prey species may also reside. Methods. With GPS collars, we tracked 38 domestic cats at three sites (one rural, two urban fringe) where small reserves contained threatened lizard species. Key results. Home ranges (95% kernel density estimates) were considerably larger for cats at the rural site (0.3–69 ha) than at urban-fringe sites (0.35–19 ha at Kaitorete Spit and 0.2–9 ha at Otago Peninsula), and were larger at night than day. Resource selection ratios indicated avoidance of open areas with little cover, such as cultivated areas (farmland), tussock grassland and duneland, whereas sources of cover such as trees and buildings were preferred. Maximum distances moved and large variability between individual cats suggest buffers in rural landscapes would need to be at least 2.4 km wide, whereas those in urban-fringe habitat could be half as large. Conclusions. Despite significant home-range size differences exhibited by cats living in rural v. urban-fringe habitats, exclusion zones would need to be wide to account for considerable inter-cat variation in movement behaviour. Implications. The size of an effective cat-exclusion zone should represent the specific landscape, amount of residential development and substantial variability between individual cats.
Abstract Context Wildlife tourism is expanding and can detrimentally affect taxa such as penguins, if not managed carefully. The yellow-eyed penguin (Megadyptes antipodes) is an endangered species, with mainland populations projected to decline to extinction in the next 40 years, despite conservation interventions. Their nesting sites are exposed to increasing numbers of human visitors, which contributes to reduced reproductive success. AimsWe evaluated the effectiveness of a breeding colony (Boulder Beach) closure to the public, which was implemented to reduce visitor disturbance. MethodsWe compared reproductive success 5 years before and 5 years during the closure with success at an adjacent site (Sandfly Bay) that experiences high human disturbance, over the same time periods. Key resultsBeach closure did not result in an increase in chick mass or survival at Boulder Beach; however, trends at adjacent Sandfly Bay suggested that, without the closure, chick survival at Boulder Beach would likely have declined. Chick survival decreased at Sandfly Bay across the two 5-year periods, whereas chick survival at Boulder Beach did not decline, but remained constant during the closure years. ConclusionsThe beach closure was beneficial because it appeared to buffer environmental factors, so that mean chick survival remained constant rather than declining. Implications Beach closures might be difficult to implement because of public expectations regarding free access to coastal land in New Zealand, but they should be considered at sites where increasing numbers of visitors are likely to have detrimental impacts on wildlife. Without urgent action, these culturally important animals will likely be extinct on mainland New Zealand within the next few decades. Beach closures may represent an effective management measure to increase population resilience by decreasing the detrimental impacts of visitors on breeding success.
Abstract Context. Diet variability is a significant driver of seabird decline; however, data on seabird diet composition and trends have been affected by changes in precision and resolution owing to the evolution of different sampling methods over time. We investigated the effectiveness of applying a passive molecular diet method using faeces obtained from the endangered yellow-eyed penguin. Aims. To assess the feasibility of applying DNA metabarcoding methods to yellow-eyed penguin faeces to evaluate diet, and to compare the reliability of diet results derived from adults and chicks, and from latrine versus fresh faecal samples. Methods. We collected 313 faecal samples from yellow-eyed penguins resident on the Otago coast of New Zealand from October 2016 to August 2017. We used polymerase chain reaction (PCR) with mitochondrial 16S cephalopod and chordate primers to amplify prey DNA present in the faecal samples, and tested the completeness of our assembled reference databases based on previous diet research. Amplified prey DNA sequences were then assigned to taxa from our reference databases by using QIIME2. Key results. Mitochondrial 16S chordate PCR primers were effective at identifying 29 fish taxa, with 98.3% of amplified sequences being identified to species or genus level in 193 samples (61.7% collected). There was no significant difference in the number, occurrence or proportion of ray-finned fish prey DNA sequences derived from fresh samples or latrines. Mitochondrial 16S cephalopod PCR primers classified 1.98% of amplified DNA sequences as targets, with 96.5% of these target sequences being identified to species or genus level in 48 samples (15.3% collected), and five taxa identified. Conclusions. We recommend the collection of latrine samples to enable long-term monitoring of the diet of yellow-eyed penguins, which will optimise the trade-off between wildlife disturbance and dietary resolution. Further refinement is needed to identify cephalopod dietary components for yellow-eyed penguins, because our cephalopod primers were not as specific as those used for ray-finned fishes, amplifying a large number (>98%) of non-cephalopod species. Implications. DNA metabarcoding offers a robust and comprehensive alternative to other, more intrusive, seabird diet-assessment methods, but still requires parallel studies to provide critical information on prey size, true diet composition and diet quality.
Cumulative human impacts across the world's oceans are considerable. We therefore examined a single model taxonomic group, the penguins (Spheniscidae), to explore how marine species and communities might be at risk of decline or extinction in the southern hemisphere. We sought to determine the most important threats to penguins and to suggest means to mitigate these threats. Our review has relevance to other taxonomic groups in the southern hemisphere and in northern latitudes, where human impacts are greater. Our review was based on an expert assessment and literature review of all 18 penguin species; 49 scientists contributed to the process. For each penguin species, we considered their range and distribution, population trends, and main anthropogenic threats over the past approximately 250 years. These threats were harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species. Their future resilience to further climate change impacts will almost certainly depend on addressing current threats to existing habitat degradation on land and at sea. We suggest protection of breeding habitat, linked to the designation of appropriately scaled marine reserves, including in the High Seas, will be critical for the future conservation of penguins. However, large-scale conservation zones are not always practical or politically feasible and other ecosystem-based management methods that include spatial zoning, bycatch mitigation, and robust harvest control must be developed to maintain marine biodiversity and ensure that ecosystem functioning is maintained across a variety of scales.
Cumulative human impacts across the world's oceans are considerable. We therefore examined a single model taxonomic group, the penguins (Spheniscidae), to explore how marine species and communities might be at risk of decline or extinction in the southern hemisphere. We sought to determine the most important threats to penguins and to suggest means to mitigate these threats. Our review has relevance to other taxonomic groups in the southern hemisphere and in northern latitudes, where human impacts are greater. Our review was based on an expert assessment and literature review of all 18 penguin species; 49 scientists contributed to the process. For each penguin species, we considered their range and distribution, population trends, and main anthropogenic threats over the past approximately 250 years. These threats were harvesting adults for oil, skin, and feathers and as bait for crab and rock lobster fisheries; harvesting of eggs; terrestrial habitat degradation; marine pollution; fisheries bycatch and resource competition; environmental variability and climate change; and toxic algal poisoning and disease. Habitat loss, pollution, and fishing, all factors humans can readily mitigate, remain the primary threats for penguin species. Their future resilience to further climate change impacts will almost certainly depend on addressing current threats to existing habitat degradation on land and at sea. We suggest protection of breeding habitat, linked to the designation of appropriately scaled marine reserves, including in the High Seas, will be critical for the future conservation of penguins. However, large-scale conservation zones are not always practical or politically feasible and other ecosystem-based management methods that include spatial zoning, bycatch mitigation, and robust harvest control must be developed to maintain marine biodiversity and ensure that ecosystem functioning is maintained across a variety of scales. ; Los impactos humanos acumulativos a lo largo de los océanos del planeta son considerables. Por eso examinamos un solo modelo de grupo taxonómico, los pingüinos (Sphenischidae), para explorar cómo las especies y las comunidades marinas pueden estar en riesgo de disminuir o de extinguirse en el hemisferio sur. Buscamos determinar la amenaza más importante para los pingüinos y sugerir métodos para mitigar estas amenazas. Nuestra revisión tiene relevancia para otros grupos taxonómicos en el hemisferio sur y en las latitudes norteñas, donde los impactos humanos son mayores. Nuestra revisión se basó en una evaluación experta y una revisión de literaratura de las 18 especies de pingüinos; 49 científicos contribuyeron al proceso. Para cada especie de pingüino, consideramos su rango y distribución, tendencias poblacionales y las principales amenazas antropogénicas en aproximadamente los últimos 250 años. Estas amenazas fueron la captura de adultos para obtener aceite, piel y plumas y el uso como carnada para la pesca de cangrejos y langostas: la recolección de huevos; la degradación del hábitat terrestre; la contaminación marina; la pesca accesoria y la competencia por recursos; la variabilidad ambiental y el cambio climático; y el envenenamiento por algas tóxicas y enfermedades. La pérdida de hábitat, la contaminación y la pesca, todos factores que los humanos pueden mitigar, siguen siendo las amenazas principales para las especies de pingüinos. Su resiliencia futura a más impactos por cambio climático dependerá certeramente de que nos enfoquemos en las amenazas actuales a la degradación de hábitats existentes en tierra y en el mar. Sugerimos que la protección de hábitats de reproducción, en conjunto con la designación de reservas marinas de escala apropiada, incluyendo alta mar, será crítica para la conservación futura de los pingüinos. Sin embargo, las zonas de conservación a gran escala no son siempre prácticas o políticamente viables, y otros métodos de manejo basados en ecosistemas que incluyen la zonificación espacial, la mitigación de captura accesoria, y el control fuerte de captura deben desarrollarse para mantener la biodiversidad marina y asegurar que el funcionamiento de los ecosistemas se mantenga a lo largo de una variedad de escalas. ; Fil: Trathan, Phil N. British Antartic Survey; Reino Unido ; Fil: Garcia Borboroglu, Jorge Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina ; Fil: Boersma, P. Dee. University of Washington; Estados Unidos ; Fil: Bost, Charles André. Centre d´Etudes Biologiques de Chizé; Francia ; Fil: Crawford, Robert J. M. Department of Environmental Affairs; Sudáfrica ; Fil: Crossin, Glenn T. Dalhousie University Halifax; Canadá ; Fil: Cuthbert, Richard. Royal Society for the Protection of Birds; Reino Unido ; Fil: Dann, Peter. Phillip Island Nature Parks; Australia ; Fil: Davis, Lloyd Spencer. University Of Otago; Nueva Zelanda ; Fil: de la Puente, Santiago. Universidad Cayetano Heredia; Perú ; Fil: Ellenberg, Ursula. University Of Otago; Nueva Zelanda ; Fil: Lynch, Heather J. Stony Brook University; Estados Unidos ; Fil: Mattern, Thomas. University Of Otago; Nueva Zelanda ; Fil: Pütz, Klemens. Antarctic Research Trust; Alemania ; Fil: Seddon, Philip J. University Of Otago; Nueva Zelanda ; Fil: Trivelpiece, Wayne. Southwest Fisheries Science Center; Estados Unidos ; Fil: Wienecke, Bárbara. Australian Antarctic Division; Australia
