Integrating behaviour and ecology into global biodiversity conservation strategies

Abstract

Insights into animal behaviour play an increasingly central role in species-focused conservation practice. However, progress towards incorporating behaviour into regional or global conservation strategies has been more limited, not least because standardized datasets of behavioural traits are generally lacking at wider taxonomic or spatial scales. Here we make use of the recent expansion of global datasets for birds to assess the prospects for including behavioural traits in systematic conservation priority-setting and monitoring programmes. Using International Union for Conservation of Nature Red List classifications for more than 9500 bird species, we show that the incidence of threat can vary substantially across different behavioural categories, and that some types of behaviour-including particular foraging, mating and migration strategies-are significantly more threatened than others. The link between behavioural traits and extinction risk is partly driven by correlations with well-established geographical and ecological factors (e.g. range size, body mass, human population pressure), but our models also reveal that behaviour modifies the effect of these factors, helping to explain broad-scale patterns of extinction risk. Overall, these results suggest that a multi-species approach at the scale of communities, continents and ecosystems can be used to identify and monitor threatened behaviours, and to flag up cases of latent extinction risk, where threatened status may currently be underestimated. Our findings also highlight the importance of comprehensive standardized descriptive data for ecological and behavioural traits, and point the way towards deeper integration of behaviour into quantitative conservation assessments. 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'.

Keywords: behavioural ecology; birds; indicators; latent risk; macroecology; priority-setting.

Figure 1.

Extrinsic and intrinsic factors associated with extinction risk or conservation status at global scales. Extrinsic factors include anthropogenic threats to species and the biogeographic and environmental context; intrinsic factors include population and ecological niche dimensions. This diagram summarizes the types of traits that are either available or desirable when constructing models of conservation risk at macroecological (continental or global) scales; numerous additional factors may impinge on conservation assessments in particular clades or species. Red/bold text indicates datasets currently available for all species in well studied groups like birds. Availability of data is currently biased towards environmental, biogeographic and population attributes, whereas data tend to be unavailable, uncertain or sparse for most ecological variables, and absent for behavioural variables. (Online version in colour.)

Figure 2.

The percentage of threatened species in different behavioural categories: (a) foraging behaviour (1 foraging generalist, 2 bark gleaning, 3 aerial screening, 4 aerial sallying, 5 arboreal gleaning, 6 ground foraging, 7 aquatic plunge, 8 aquatic dive, 9 aquatic surface); (b) mating behaviour (1 monogamy with infrequent polygyny, 2 monogamy with frequent polygyny, 3 monogamy, 4 polygyny), (c) migratory behaviour (1 migrant, 2 partial or short-distance migrant, 3 sedentary); (d) breeding system (1 cooperative, 2 non-cooperative); (e) territoriality (1 weak, 2 strong, 3 none); (f) nest placement (1 cavity, 2 exposed elevated, 3 exposed ground). The width of each segment indicates the proportion of all species (n = 9576) in each behavioural category. Segment heights indicate the percentage of species threatened in each category. Colours indicate threat level (Critically endangered (CR), Endangered (EN), Vulnerable (VU) and Near Threatened (NT)).

Figure 3.

The relative contribution of anthropogenic, ecological and behavioural predictors to explaining (a) threat across all birds (n = 9658) and (b) level of threat (i.e. Vulnerable versus Endangered, Critically Endangered or Extinct) among threatened species (n = 1251). The contribution of each predictor is quantified as the difference in AIC between the full model and a model excluding each variable. Predictors are shaded according to variable type. The dashed line indicates a difference of two AIC units indicating strong support for predictor inclusion.

Figure 4.

The influence of behaviour on levels of threat across the world's birds (n = 9658). (a) Effects of range size mediated by clutch size, (b) effects of body size mediated by migratory behaviour, (c) effects of human population density mediated by foraging behaviour, (d) island dwelling, (e) diet, (f) foraging behaviour, (g) mating behaviour, (h) breeding system, (i) migratory behaviour, (j) territoriality, (k) nest placement, and (l) clutch size. Results are from a generalized linear mixed effects model including all predictor variables and family as a random effect. Clutch size is a continuous variable but is here shown as a binary trait (small or large clutch size) to illustrate the interaction with range size (a). Bars indicate the 95% prediction interval. (Online version in colour.)