Using Bayesian mark-recapture modelling to quantify the strength and duration of post-release effects in reintroduced populations

Translocated animals often suffer elevated mortality during some acclimation period after release. Such post-release effects must be accounted for when estimating normal survival rates and therefore predicting population persistence. The standard approach for doing this is to nominate a fixed acclimation period, and either i) exclude survival data over that period, or ii) use model selection criteria to test whether survival differs over that period. We present a more flexible approach where the acclimation period is treated as unknown and is estimated simultaneously with the pre- and post-acclimation survival probabilities. We illustrate this approach using survival data for six reintroduced populations involving three New Zealand forest bird species. Analyses of the complete data sets (22–73 surveys conducted over 4–14 years) indicated that significant post-release effects occurred in at least one sex in five of the six populations, with 30–84% mortality attributable to post-release effects over acclimation periods ranging from 1 to 9 months. When we applied the approach to just the first year of data for each population, the estimated normal survival rates were consistent with those obtained from the complete data sets, and always at least as accurate as our previous approach of excluding data up to the next breeding season after translocation. The flexible approach therefore appears to be effective for accounting for post-release effects in survival estimation, and is beneficial in quantifying both the strength and duration of those effects so that pre- and post-release management strategies are better informed

Comparing post-release survival and habitat use by captive-bred Cabot’s Tragopan (Tragopan caboti) in an experimental test of soft-release reintroduction strategies

Background: Restoring a viable population by reintroduction is the ultimate goal of a large number of ex situ conservation projects for endangered animals. However, many reintroductions fail to establish a population in the wild, partly because released animals cannot acclimate to the native environment of the release site, resulting in very low survival rates. Acclimation training is a technique to resolve this problem, although it does not have positive results in all species. We tested whether acclimation training and soft-release could improve the reintroduction success for captive-bred Cabot’s Tragopan (Tragopan caboti), an endangered pheasant in southern China. Methods: Reintroduction of captive-bred Cabot’s Tragopan was carried out in the Taoyuandong National Nature Reserve, China from 2010 to 2011. We built a soft-release enclosure for acclimation training in the typical montane habitat of this pheasant. Nine birds were acclimated to the environment of this release site in this cage for more than 50 days before release (“trained birds”), while 11 birds remained only in the cage for 3 days prior to release (“untrained birds”). Released birds were tagged with a collar radio-transmitter. Results: Post-release monitoring revealed that the survival rate of trained birds was higher than that of untrained birds after 50 days (trained: 85.7%; untrained: 20.0%). Cox regression analysis showed that there was a significant difference in the mortality rates between the trained and untrained birds. In addition, a survey of the habitat of the experimental and the control groups showed significant differences in habitat selection between the groups. Conclusion: Our study suggests that pre-release acclimatization training is an important factor that can lead to improved survival and habitat selection of captive-bred reintroduced tragopans

Machine Learning for digital document processing: from layout analysis to metadata extraction

In the last years, the spread of computers and the Internet caused a significant amount of documents to be available in digital format. Collecting them in digital repositories raised problems that go beyond simple acquisition issues, and cause the need to organize and classify them in order to improve the effectiveness and efficiency of the retrieval procedure. The success of such a process is tightly related to the ability of understanding the semantics of the document components and content. Since the obvious solution of manually creating and maintaining an updated index is clearly infeasible, due to the huge amount of data under consideration, there is a strong interest in methods that can provide solutions for automatically acquiring such a knowledge. This work presents a framework that intensively exploits intelligent techniques to support different tasks of automatic document processing from acquisition to indexing, from categorization to storing and retrieval. The prototypical version of the system DOMINUS is presented, whose main characteristic is the use of a Machine Learning Server, a suite of different inductive learning methods and systems, among which the more suitable for each specific document processing phase is chosen and applied. The core system is the incremental first-order logic learner INTHELEX. Thanks to incrementality, it can continuously update and refine the learned theories, dynamically extending its knowledge to handle even completely new classes of documents. Since DOMINUS is general and flexible, it can be embedded as a document management engine into many different Digital Library systems. Experiments in a real-world domain scenario, scientific conference management, confirmed the good performance of the proposed prototype

Male mate guarding in a socially monogamous mammal, the round-eared sengi: on costs and trade-offs

Abstract Mate guarding is predicted to be one of the driving forces for the evolution of monogamy, but supporting evidence in free-living mammals is rare. The goals of our study were three-pronged. First, we tested if mate guarding, measured as intrapair distance, occurs as a behavioral tactic in round-eared sengis (Macroscelides proboscideus), a socially monogamous species lacking paternal care and in which females breed asynchronously, producing 2–3 litters during an 8-month long breeding season. Second, we determined if mate guarding involves costs which we identified as changes in male body mass. Third, we investigated whether variation in individual investment in mate guarding depended on the males’ body mass and the number of neighboring males. Field data were collected in a semidesert in South Africa using radio-tracking, trapping, and direct observations during three successive breeding seasons. Mate guarding strongly depended on the females’ reproductive state, and all males started to guard their mates prior to and during estrus, as exemplified by reduced intrapair distance. Mate guarding incurred costs: overall, males lost about 5% of body mass. Male body mass loss and initial body mass were negatively related to the intensity of precopulatory mate guarding. Furthermore, during estrus intrapair distance was inversely correlated with the number of neighboring males. The results show that mate guarding is the predominant male tactic in round-eared sengis. However, since mate guarding imposed costs, males may balance benefits and costs associated with guarding by varying their effort in relation to their physical capabilities and the competitive environment