Habitat Selection and Post-Release Movement of Reintroduced Brown Treecreeper Individuals in Restored Temperate Woodland

It is essential to choose suitable habitat when reintroducing a species into its former range. Habitat quality may influence an individual's dispersal decisions and also ultimately where they choose to settle. We examined whether variation in habitat quality (quantified by the level of ground vegetation cover and the installation of nest boxes) influenced the movement, habitat choice and survival of a reintroduced bird species. We experimentally reintroduced seven social groups (43 individuals) of the brown treecreeper (Climacteris picumnus) into two nature reserves in south-eastern Australia. We radio-tracked 18 brown treecreepers from release in November 2009 until February 2010. We observed extensive movements by individuals irrespective of the release environment or an individual's gender. This indicated that individuals were capable of dispersing and actively selecting optimum habitat. This may alleviate pressure on wildlife planners to accurately select the most optimum release sites, so long as the species' requirements are met. There was significant variation in movement between social groups, suggesting that social factors may be a more important influence on movement than habitat characteristics. We found a significant effect of ground vegetation cover on the likelihood of settlement by social groups, with high rates of settlement and survival in dry forests, rather than woodland (where the species typically resides), which has implications for the success of woodland restoration. However, overall the effects of variation in habitat quality were not as strong as we had expected, and resulted in some unpredicted effects such as low survival and settlement in woodland areas with medium levels of ground vegetation cover. The extensive movement by individuals and unforeseen effects of habitat characteristics make it difficult to predict the outcome of reintroductions, the movement behaviour and habitat selection of reintroduced individuals, particularly when based on current knowledge of a species' ecology.The project has been made possible by funding from:Birding NSW (www.birdingnsw.org.au), Birdlife Australia – Stuart Leslie Bird Research Award (www.birdlife.org.au), Canberra Ornithologists Group, Canberra Birds Conservation Fund (www.canberrabirds.org.au),The Conservation and Landscape Ecology Group within the Fenner School of Environment and Society at The Australian National University (http://fennerschool-research.anu.edu.au/​cle/), The Fenner School of Environment and Society at The Australian National University (http://fennerschool.anu.edu.au/), The Foundation for National Parks and Wildlife (www.fnpw.org.au), Gould League of NSW 2010 Centenary Year Cayley Memorial Scholarship (www.gould.edu.au), The Mulligans Flat-Goorooyarroo Woodland Experiment (ARC Linkage Project LP0561817) (http://www.mfgowoodlandexperiment.org.au​/),The Norman Wettenhall Foundation (reference 20108002) (www.nwf.org.au), In-kind contribution was greatly appreciated from CSIRO Ecosystem Sciences (http://www.csiro.au/Organisation-Structu​re/Divisions/Ecosystem-Sciences.aspx) and The Parks and Conservation Service within the Australian Capital Territory Government Department of Territory and Municipal Services (http://www.tams.act.gov.au/play/pcl). One field assistant was employed (Jenny Newport) using funds from Conservation and Landscape Ecology Group and the Mulligans Flat-Goorooyarroo Woodland Experiment to assist in collecting data obtained through radio-tracking reintroduced brown treecreepers

Habitat Selection and Behaviour of a Reintroduced Passerine: Linking Experimental Restoration, Behaviour and Habitat Ecology

Habitat restoration can play an important role in recovering functioning ecosystems and improving biodiversity. Restoration may be particularly important in improving habitat prior to species reintroductions. We reintroduced seven brown treecreeper (Climacteris picumnus) social groups into two nature reserves in the Australian Capital Territory in south-eastern Australia. This study provided a unique opportunity to understand the interactions between restoration ecology, behavioural ecology and habitat ecology. We examined how experimental restoration treatments (addition of coarse woody debris, variations in ground vegetation cover and nest box installation) influenced the behaviour and microhabitat use of radio-tracked individuals to evaluate the success of restoration treatments. The addition of coarse woody debris benefited the brown treecreeper through increasing the probability of foraging on a log or on the ground. This demonstrated the value of using behaviour as a bio-indicator for restoration success. Based on previous research, we predicted that variations in levels of ground vegetation cover would influence behaviour and substrate use, particularly that brown treecreepers would choose sites with sparse ground cover because this allows better access to food and better vigilance for predators. However, there was little effect of this treatment, which was likely influenced by the limited overall use of the ground layer. There was also little effect of nest boxes on behaviour or substrate use. These results somewhat confound our understanding of the species based on research from extant populations. Our results also have a significant impact regarding using existing knowledge on a species to inform how it will respond to reintroduction and habitat restoration. This study also places great emphasis on the value of applying an experimental framework to ecological restoration, particularly when reintroductions produce unexpected outcomes.The project has been made possible by funding from Birding NSW (www.birdingnsw.org.au), Birdlife Australia – Stuart Leslie Bird Research Award (www.birdlife.org.au), Canberra Ornithologists Group, Canberra Birds Conservation Fund (www.canberrabirds.org.au), the Conservation and Landscape Ecology Group within the Fenner School of Environment and Society at The Australian National University (http://fennerschool-research.anu.edu.au/cle/), the Fenner School of Environment and Society at The Australian National University (http://fennerschool.anu.edu.au/), the Foundation for National Parks and Wildlife (www.fnpw.org.au), Gould League of NSW 2010 Centenary Year Cayley Memorial Scholarship (www.gould.edu.au), the Mulligans Flat-Goorooyarroo Woodland Experiment (ARC Linkage Project LP0561817) (http://www.mfgowoodlandexperiment.org.au/), and the Norman Wettenhall Foundation (reference 20108002) (www.nwf.org.au). In-kind contribution was greatly appreciated from CSIRO Ecosystem Sciences (http://www.csiro.au/Organisation-Structure/Divisions/Ecosystem-Sciences.aspx) and The Parks and Conservation Service within the Australian Capital Territory Government Department of Territory and Municipal Services (http://www.tams.act.gov.au/parks-recreation). One field assistant was employed (Jenny Newport) using funds from Conservation and Landscape Ecology Group and the Mulligans Flat-Goorooyarroo Woodland Experiment to assist in collecting data obtained through radio-tracking reintroduced brown treecreepers. Otherwise, individuals that were employed or contracted by the funders (other than the named authors) did not play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript

Positive effects of helpers on reproductive success in the brown treecreeper and the general importance of future benefits

1. Numerous studies of cooperatively breeding species have tested for effects of helpers on reproductive success to evaluate hypotheses for the evolution of cooperation, but relatively few have used experimental or statistical approaches that control fo

Comparative demography of treecreepers: evaluating hypotheses for the evolution and maintenance of cooperative breeding

Despite the long history of research on cooperative breeding, few comparative studies have been undertaken to test hypotheses for the evolution and maintenance of delayed dispersal using data from both cooperative and noncooperative species. We tested predictions about demographic differences between cooperative and noncooperative species based on four hypotheses for the evolution of delayed dispersal: the ecological constraints hypothesis, the life history hypothesis, the broad constraints hypothesis and the benefits-of-philopatry hypothesis. We controlled for phylogeny and habitat by comparing sympatric populations of two Australasian treecreepers (Climacteridae): the cooperatively breeding brown treecreeper, Climacteris picumnus, and the pair-breeding white-throated treecreeper, Cormobates leucophaea, which has lost cooperative breeding despite phylogenetic conservation of the trait in most of the treecreeper lineage. Our data failed to support nearly every prediction of the constraints and life history hypotheses. The two species had similar levels of constraints and similar life histories, and any significant differences were in the opposite direction to those predicted. However, the cooperative species was characterized by significantly higher variance in reproductive success as a result of group size effects, supporting the benefits-of-philopatry hypothesis as an explanation for the maintenance of delayed dispersal. Our comparisons also suggest that the benefits parents derive from group living determine whether or not they tolerate offspring on the natal territory. We therefore propose an antipredator tactics hypothesis in which delayed dispersal will initially evolve or be lost in particular taxa depending on the relative costs and benefits of vigilance and active defence versus concealment-based antipredator tactics

Dispersal range analysis: quantifying individual variation in dispersal behaviour

A complete understanding of animal dispersal requires knowledge not only of its consequences at population and community levels, but also of the behavioural decisions made by dispersing individuals. Recent theoretical work has emphasised the importance of this dispersal process, particularly the phase in which individuals search the landscape for breeding opportunities. However, empirical advances are currently hampered by a lack of tools for quantifying these dispersal search tactics. Here, we review existing methods for quantifying movement that are appropriate for the dispersal search process, describe several new techniques that we developed for characterising movement and behaviour through an individual's dispersal range, and illustrate their use with data from Australasian treecreepers (Climacteridae). We also describe how the quantitative parameters we discuss are calculated in a freely available computer software package that we designed. Specifically, we present methods for calculating the area searched during dispersal, search rate, thoroughness, intensity, philopatry of search, timing of exploration, and surreptitiousness. When we applied this approach to the study of dispersal in treecreepers, we found that search area, philopatry and timing of exploration showed the greatest individual variation. Furthermore, search area, search rate, thoroughness and philopatry of search were all correlated, suggesting they may be useful parameters for further research on the causes and consequences of different dispersal search tactics. Finally, we make recommendations for modifying radiotracking protocols to facilitate more accurate assessment of individual variation in the dispersal process, and suggest future directions for this type of empirical work at the interface of population and behavioural ecology

Fractal analysis can explain individual variation in dispersal search paths

The use of fractal analysis to study animal movement paths has been criticized because the inherent assumptions of the technique are rarely discussed, and most movement paths violate the assumption of scale invariance. While this violation may prohibit the use of the technique for population-level prediction, it need not restrict the analysis of individual variation in movement patterns, an application of fractal theory that has received relatively little research attention. Therefore, we review fractal analysis and its assumptions, highlighting three ways in which it can yield useful information about individual movement paths regardless of whether or not the assumption of scale invariance has been met. We used these techniques to analyze patterns of individual variation and potential causes of variation in the dispersal searching paths of two species of Australian treecreeper (Passeriformes: Climacteridae). By comparing relative fractal D, or the relative tortuosity and thus thoroughness of search paths, we found that individuals faced a trade-off between thoroughness and the extent of searching. Thoroughness also differed between the sexes and the species, possibly as a direct consequence of mating and social systems. For almost all individuals, thoroughness varied depending on the spatial scale at which it was examined, revealing three distinct domains of scale in which movement tactics vary because movement is used for very different purposes. Variability in movement tactics was greatest in the largest spatial-scale domain, the one used exclusively for dispersal movements, suggesting that dispersal tactics show more intraspecific variation than other types of movement because dispersal, decisions are influenced by a greater variety of factors. Our results reveal that fractal analysis can provide useful information on the causes of and constraints on individual movement strategies, creating empirically based models of animal movement and thus a firm foundation for modeling movement processes from individual to landscape scales