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Reintroduction success depends in part on the release strategy used. Benefits are attributed to particular release strategies but few studies have tested these assumptions. We examined the effect of delayed release (a form of so-called soft release) on the survival of a threatened passerine, the New Zealand hihi Notiomystis cincta, for up to 7 months after translocation. Birds were captured at the source site and then held in captivity for disease screening. They were then taken to the release site, where 30 were released immediately and 28 were held for a further 2–4 days in an on-site aviary. Twenty-four birds were fitted with radio-transmitters. A 1,300 ha area around the release site was searched fortnightly, and survival was analysed using a multi-state model that accounted for the effect of transmitters on detection probability. Our results indicated that delayed release had a negative effect on long-term survival, but no effect was apparent in the first 6 weeks. Survival probability from 6 weeks to 7 months post-release was 0.77 ± SE 0.20 for immediate-release birds and 0.04 ± SE 0.06 for delayed-release birds. Our results suggest that there is a misconception about the benefits of delayed-release strategies during translocation of wild animals. Studies that have demonstrated a benefit of delayed release in other bird species used captive-bred individuals, and we suggest that wild individuals perceive captivity differently. We recommend that biological context is considered before delayed release is used in translocations. [ABSTRACT FROM PUBLISHER]

Awareness of parasite risks in translocations has prompted the development of parasite management protocols, including parasite risk assessment, parasite screening and treatments. However, although the importance of such measures seems obvious it is difficult to know whether the measures taken are effective, especially when working with wild populations. We review current methods in one extensively researched case study, the endemic New Zealand passerine bird, the hihi Notiomystis cincta. Our review is structured around four of the 10 questions proposed by Armstrong & Seddon (Trends in Ecology & Evolution, 2008: 23, 20–25) for reintroduction biology. These four questions can be related directly to parasites and parasite management and we recommend using this framework to help select and justify parasite management. Our retrospective study of recent disease and health screening in hihi reveals only partial overlap with these questions. Current practice does not focus on, or aim to reduce, the uncertainty in most steps of the risk assessment process or on evaluating whether the measures are effective. We encourage targeted parasite management that builds more clearly on available disease risk assessment methodologies and integrates these tools within a complete reintroduction plan. [ABSTRACT FROM AUTHOR]

Sex-biased natal dispersal is prevalent in many avian species, with females typically dispersing further than males. We examined natal dispersal patterns in an growing reintroduced population of hihi (stitchbird, Notiomystis cincta) on Tiritiri Matangi Island in New Zealand. Hihi nest almost exclusively in the nest boxes provided throughout the island, and breeding locations have been recorded since the 1997-1998 season. The population grew from 16 to 170 birds in the 10 years since establishment in 1995, and also experienced substantial changes in adult sex ratio over this period. We calculated distances from natal to breeding locations to examine the dynamics of natal dispersal with sex, population density and sex ratio, and maternal and environmental effects. Overall, females dispersed significantly further than males, with permutation tests indicating that mean female dispersal distance was significantly higher than expected if they selected boxes at random, and male mean dispersal distance was significantly less than expected if they selected boxes at random. General linear mixed modelling also revealed sex-specific changes in dispersal behaviour over time that were correlated with changes in population density and sex ratio, and a strong effect of the maternal females' identity. The mean dispersal distance of males decreased with density, with the number of the juveniles in the cohort as the best correlate. We suggest that males are able to disperse further to gain the highest quality open territories at lower population densities, whereas dispersal distances become increasingly constrained by territory availability, and possibly variation in mating strategy, at higher densities. In contrast, female dispersal showed a weak positive density-dependent relationship, but was more strongly influenced by sex ratio, with dispersal distances decreasing with an increasing male bias in the population. We also found a strong effect of the maternal female that could not be explained solely by nest box location. Overall, these results imply a critical role of social context, including population size, density, and sex ratio in influencing natal dispersal dynamics in a closed, insular population of hihi, and have important conservation management applications for future translocation design and implementation for this endangered species. [ABSTRACT FROM AUTHOR]