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Mammalian carnivores rely on their sharp teeth to effectively kill and consume prey. However, over time this causes wear and breakage that alters tooth shape, reducing their effectiveness. Extreme tooth wear and damage is especially prevalent in species that scavenge carcasses, like the Tasmanian devil (Sarcophilus harrisii), which are well known for their voracious appetites and ability to consume almost all of a carcass, including bone. In this study, we comprehensively describe tooth wear in captive and wild devils to look for differences in the patterns and rate of wear between these environments. To do this we surveyed tooth condition in skulls from 182 wild and 114 captive devils for which age was estimated using canine over-eruption. We found the types of tooth wear documented were the same in captive and wild devils, but captive animals have less severe wear than wild devils of the same estimated age. There was no difference in the proportion of captive or wild individuals with broken canine or molar teeth; however, breakage occurred at a younger age in wild devils. Although not considered anomalous or harmful, this indicates a difference in the way teeth are being used and/or the foods consumed between captive and wild devils. We hypothesize how these results relate to differences in diet or behavior that may stem from their various feeding environments, for example, higher quality food (fresh, whole, and yet to be scavenged carcasses) provided to captive devils likely causes less wear. Further, we support management options that closely replicate wild diet items and behaviors suitable for a long-term insurance population.

Aim: As populations decline they become harder to detect simply because there are fewer animals to observe. In such cases, survey effort that was once reliable may become inadequate and the species incorrectly labelled locally extinct, causing management efforts to cease. For declining populations, then, we need to determine the survey effort necessary to detect the species, assuming only a single individual is present at a site. Detectability, however, often varies wildly with seasonal, behavioural and environmental variables. Thus, we need statistical analyses and survey design which can deal with highly variable detection rates and allow us to detect even very small populations. This is especially true in Australia, where many mammal species are experiencing serious decline. Here, we examine a threatened Australian rodent, the New Holland Mouse (Pseudomys novaehollandiae): we determine minimum survey requirements for reliable detection and show that historical survey effort is inadequate to assert local extinction. Location: Victoria, Australia. Methods: Using a 48-year live-trapping dataset, we estimated P. novaehollandiae abundance and detectability using N-mixture modelling in a Bayesian framework, testing the effects of seasonal fluctuations and environmental variables to determine ideal conditions for occupancy surveys. We used these findings to assess the adequacy of historical resurvey efforts in confirming local extinctions. Results: We found that detectability followed seasonal fluctuations distinct from changes in abundance, was strongly reduced by brighter moon phases, and slightly increased over the course of a survey and when raining. When abundance was low, standard historical survey efforts were inadequate to assert the species' absence with appropriate statistical confidence, indicating that further surveys would be required to test purported local extinctions. Main conclusions: Our results highlight the potential for considerable intra-species heterogeneity in detectability caused by shifting local abundances and survey conditions, as well as the importance of accounting for detectability when monitoring threatened and declining species.

Captive breeding followed by reintroduction to the wild is a common component of conservation management plans for various taxa. Although it is commonly used, captive breeding can result in morphological changes, including brain size decrease. Brain size reduction has been associated with behavioral changes in domestic animals, and such changes may negatively influence reintroduction success of captive-bred animals. Many marsupials are currently bred in captivity for reintroduction, yet the impacts of captive breeding on brain size have never been studied in this taxa. We investigated the impacts of a few generations (2-7) of captive breeding on brain volume in the stripe-faced dunnart (Sminthopsis macroura), and found that captive breeding in a relatively enriched environment did not cause any changes in brain volume. Nonetheless, we advocate that great care be taken to provide suitable husbandry conditions and to minimize the number of captive generations if marsupial reintroduction programs are to be successful.