A modelling framework for integrating reproduction, survival and count data when projecting the fates of threatened populations.

A key goal of ecological research is to obtain reliable estimates of population demographic rates, abundance and trends. However, a common challenge when studying wildlife populations is imperfect detection or breeding observation, which results in unknown survival status and reproductive output for some individuals. It is important to account for undetected individuals in population models because they contribute to population abundance and dynamics, and can have implications for population management. Promisingly, recent methodological advances provide us with the tools to integrate data from multiple independent sources to gain insights into the unobserved component of populations. We use data from five reintroduced populations of a threatened New Zealand bird, the hihi (Notiomystis cincta), to develop an integrated population modelling framework that allows missing values for survival status, sex and reproductive output to be modelled. Our approach combines parallel matrices of encounter and reproduction histories from marked individuals, as well as counts of unmarked recruits detected at the start of each breeding season. Integrating these multiple data types enabled us to simultaneously model survival and reproduction of detected individuals, undetected individuals and unknown (never detected) individuals to derive parameter estimates and projections based on all available data, thereby improving our understanding of population dynamics and enabling full propagation of uncertainty. The methods presented will be especially useful for management programmes for populations that are intensively monitored but where individuals are still imperfectly detected, as will be the case for most threatened wild populations.

Links between personality, early natal nutrition and survival of a threatened bird.

There is growing recognition that variation in animal personality traits can influence survival and reproduction rates, and consequently may be important for wildlife population dynamics. Despite this, the integration of personality research into conservation has remained uncommon. Alongside the establishment of personality as an important source of individual variation has come an increasing interest in factors affecting the development of personality. Recent work indicates the early environment, including natal nutrition, may play a stronger role in the development of personality than previously thought. In this study, we investigated the importance of three personality metrics (activity, boldness and acclimation time) for estimating survival of a threatened species, the hihi (Notiomystis cincta), and evaluated the influence of early natal nutrition on those metrics. Our results showed that boldness (as measured from a one-off cage test) had a positive effect on the probability of juvenile hihi surviving to adulthood. There was also a tendency for juveniles that received carotenoid supplementation in the nest to be bolder than those that did not, suggesting that the early environment had some influence on the expression of boldness in juvenile hihi. Linking the development of personality traits with ultimate effects on vital rates may benefit conservation management, as it could enable developmentally targeted management interventions. To our knowledge, this study is the first to identify potential linkages between early natal nutrition, personality and fitness in a wild-living population. This article is part of the theme issue 'Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'.

Older and wiser? Age differences in foraging and learning by an endangered passerine.

Birds use cues when foraging to help relocate food resources, but natural environments provide many potential cues and choosing which to use may depend on previous experience. Young animals have less experience of their environment compared to adults, so may be slower to learn cues or may need to sample the environment more. Whether age influences cue use and learning has, however, received little experimental testing in wild animals. Here we investigate effects of age in a wild population of hihi (Notiomystis cincta), a threatened New Zealand passerine. We manipulated bird feeders using a novel colour cue to indicate a food reward; once hihi learned its location, we rotated the feeder to determine whether the birds followed the colour or returned to the previous location. Both age groups made fewer errors over trials and learned the location of the food reward, but juveniles continued to sample unrewarding locations more than adults. Following a second rotation, more adults preferred to forage from the hole indicated by the colour cue than juveniles, despite this no longer being rewarding. Overall, juveniles spent longer in the feeder arena to reach the same proportion of foraging time as adults. Combined, these results suggest that juveniles and adults may use an "explore and exploit" foraging strategy differently, and this affects how efficiently they forage. Further work is needed to understand how juveniles may compensate for their inexperience in learning and foraging strategies.

A Comparison of Disease Risk Analysis Tools for Conservation Translocations.

Conservation translocations are increasingly used to manage threatened species and restore ecosystems. Translocations increase the risk of disease outbreaks in the translocated and recipient populations. Qualitative disease risk analyses have been used as a means of assessing the magnitude of any effect of disease and the probability of the disease occurring associated with a translocation. Currently multiple alternative qualitative disease risk analysis packages are available to practitioners. Here we compare the ease of use, expertise required, transparency, and results from, three different qualitative disease risk analyses using a translocation of the endangered New Zealand passerine, the hihi (Notiomystis cincta), as a model. We show that the three methods use fundamentally different approaches to define hazards. Different methods are used to produce estimations of the risk from disease, and the estimations are different for the same hazards. Transparency of the process varies between methods from no referencing, or explanations of evidence to justify decisions, through to full documentation of resources, decisions and assumptions made. Evidence to support decisions on estimation of risk from disease is important, to enable knowledge acquired in the future, for example, from translocation outcome, to be used to improve the risk estimation for future translocations. Information documenting each disease risk analysis differs along with variation in emphasis of the questions asked within each package. The expertise required to commence a disease risk analysis varies and an action flow chart tailored for the non-wildlife health specialist are included in one method but completion of the disease risk analysis requires wildlife health specialists with epidemiological and pathological knowledge in all three methods. We show that disease risk analysis package choice may play a greater role in the overall risk estimation of the effect of disease on animal populations involved in a translocation than might previously have been realised.

Foraging for carotenoids: do colorful male hihi target carotenoid-rich foods in the wild?

Dietary access to carotenoids is expected to determine the strength of carotenoid-based signal expression and potentially to maintain signal honesty. Species that display carotenoid-based yellow, orange, or red plumage are therefore expected to forage selectively for carotenoid-rich foods when they are depositing these pigments during molt, but whether they actually do so is unknown. We set out to address this in the hihi (Notiomystis cincta), a New Zealand passerine where males, but not females, display yellow carotenoid-based plumage. We measured circulating carotenoid concentrations in male and female hihi during breeding and molt, determined the nutritional content of common foods in the hihi diet, and conducted feeding observations of male and female hihi during molt. We found that although male and female hihi do not differ significantly in plasma carotenoid concentration, male hihi have a greater proportion of carotenoid-rich foods in their diet than do females. This is a consequence of a greater fruit and lower invertebrate intake than females and an avoidance of low-carotenoid content fruit. By combining behavioral observations with quantification of circulating carotenoids, we present evidence that colorful birds forage to maximize carotenoid intake, a conclusion we would not have drawn had we examined plasma carotenoids alone.