Declining woodland birds—is our science making a difference?

Bennett, Andrew F.; Watson, David M.

doi:10.1071/muv111n1_ed

Cited by 24 publications

(22 citation statements)

References 51 publications

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“…As insectivory and ground-foraging behavior are major factors linking these species, nutrient limitation due to changing availability of preferred prey has been proposed as a possible contributor to their decline (Watson 2011). Rather than a uniquely Australian phenomenon, declines in ground-foraging insectivores have been noted in many other regions (B ö hning-Gaese et al 1993, Donald et al 2001, Sekercioglu et al 2002, hence the infl uence of prey availability (and specifi cally nutritional quality) is of wider relevance (Bennett and Watson 2011).…”

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confidence: 99%

Nutritional composition of the preferred prey of insectivorous birds: popularity reflects quality

Razeng

Watson

2014

Journal of Avian Biology

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Food availability is emerging as a key determinant of avian occurrence and habitat use in a variety of systems, but insectivores have received less attention than other groups and the potential influence of nutritional quality has rarely been considered. Rather than a uniform food source, arthropods vary greatly in terms of nutritional composition, but does this variation translate into differential consumption? Building on previous work that demonstrated clear preference for some arthropod groups by 13 species of ground‐foraging insectivores, we compare the nutritional composition of these arthropod groups with other groups commonly encountered but seldom consumed in the same habitat types. Using samples of arthropods collected from a eucalypt woodland in southern Australia, we found the high frequency prey groups (Coleoptera, Lepidoptera, Orthoptera and Araneae) consistently contained higher fractions of crude protein and total fat than the low frequency groups (Diptera, Hymenoptera and Odonata). Even more clear‐cut differences were noted in terms of micronutrients; high frequency prey containing significantly greater concentrations of seven elements than low frequency prey and significantly greater amounts per individual arthropod for all eleven elements measured. These results indicate that the nutritional quality plays an important role in prey selection in insectivores and suggests that micronutrients may be more important determinants of prey choice than previously recognized. Integrating these findings with previous work suggesting food limitation may constrain distribution patterns of birds in fragmented landscapes, we contend that variation in nutritional quality helps explain observed patterns in insectivore diets and occurrence. In addition to explaining why smaller and more disturbed habitats are unable to support resident insectivore populations, this bottom‐up mechanism may underlie the disproportionate sensitivity of insectivores to land‐use intensification.

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Nutritional composition of the preferred prey of insectivorous birds: popularity reflects quality

Razeng

Watson

2014

Journal of Avian Biology

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“…less fertile soils) generally had more native vegetation. Agriculture has been the major driver of vegetation clearing in the Australian regions examined (Bennett and Watson 2011), so soils suited to agricultural production are expected to retain less native vegetation. Similarly, hilly landscapes in temperate Australia are less conducive to agricultural and other anthropogenic land uses, and so retain more native vegetation.…”

Section: Discussionmentioning

confidence: 99%

Non-random patterns of vegetation clearing and potential biases in studies of habitat area effects

2017

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Context Native vegetation extent is often a proxy for habitat area in studies of human-modified landscapes. However, the loss and retention of native vegetation is rarely random among landscapes. Instead, the extent of native vegetation in landscapes may be correlated with abiotic factors, thereby obscuring or distorting relationships between ecological phenomena and area. Objectives We asked: (1) how has the potential for non-random vegetation loss to confound area effects been addressed in the landscape ecology literature? (2) Are consistent patterns of non-random vegetation loss and retention evident from modified regions of two countries? Methods We reviewed 118 papers that related area to an ecological response, to determine whether potential biases associated with non-random vegetation loss and retention were considered. We then analysed *18,000 100 km 2 landscape units in Australia and South Africa to identify how different abiotic factors correlate with the extent of native vegetation retained in those landscapes. Results Only 21% of the studies we reviewed explicitly or implicitly considered spatial biases in vegetation clearing. Yet, across modified regions of Australia and South Africa, landscape-scale native vegetation extent was consistently and often strongly related to abiotic factors, particularly soil properties and topographic variability. Conclusion Patterns of vegetation clearing and retention commonly reflect underlying abiotic heterogeneity. These biases, which are infrequently highlighted in studies focussing on area effects, have implications for how we assess the importance of vegetation extent for species and assemblages. Failure to account for correlates of vegetation extent risks erroneous area-based conservation prescriptions in human-modified environments.

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“…Regions of Australia with the highest LI values were characterized by a sigmoidal curve. In the southeast mainland region, with a sigmoidal curve and an LI of 61, numerous studies indicate that a number of once‐common bird species are in decline (Bennett & Watson ; Ford ). We found a similar LI score, with the same sigmoidal response curve, in the Brigalow Belt region, where trends in bird populations are less well known.…”

Section: Discussionmentioning

confidence: 99%

A composite measure of habitat loss for entire assemblages of species

Simmonds

Watson

Salazar

et al. 2019

Conservation Biology

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Habitat destruction is among the greatest threats facing biodiversity, and it affects common and threatened species alike. However, metrics for communicating its impacts typically overlook the nonthreatened component of assemblages. This risks the loss of habitat going unreported for species that comprise the majority of assemblages. We adapted a widely used measure for summarizing researcher output (the h index) to provide a metric that describes natural habitat loss for entire assemblages, inclusive of threatened and nonthreatened species. For each of 447 Australian native terrestrial bird species, we combined information on their association with broad vegetation groups with distributional range maps to identify the difference between the estimated pre‐European and current extents of potential habitat, defined as vegetation groups most closely associated with each species. From this, we calculated the loss index (LI), which revealed that 30% of native birds have each lost at least 30% of their potential natural habitat (LI = 30). At the subcontinental scale, LIs ranged from 15 in arid Australia to 61 in the highly transformed southeastern part of the country. Different subcomponents of the assemblage had different LI values. For example, Australia's parrots (n = 52 species) had an LI of 38, whereas raptors (n = 32 species) had an LI of 25. The LI is simple to calculate and can be determined using readily available spatial information on species distributions, native vegetation associations, and human impacts on natural land cover. This metric, including the curves used to deduce it, could complement other biodiversity indices if it is used for regional and global biodiversity assessments that compare the status of natural habitat extent for assemblages within and among nations, monitor changes through time, and forecast future changes to guide strategic land‐use planning. The LI is an intuitive tool that can be used to summarize and communicate how human actions affect whole assemblages, not just threatened species.

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Declining woodland birds—is our science making a difference?

Cited by 24 publications

References 51 publications

Nutritional composition of the preferred prey of insectivorous birds: popularity reflects quality

Nutritional composition of the preferred prey of insectivorous birds: popularity reflects quality

Non-random patterns of vegetation clearing and potential biases in studies of habitat area effects

A composite measure of habitat loss for entire assemblages of species

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