Research progress in avian dispersal behavior

Dispersal, defined as a linear spreading move-ment of individuals away from others of the population is a fundamental characteristic of organisms in nature. Dispersal is a central concept in ecological, behavioral and evolutionary studies, driven by different forces such as avoidance of inbreeding depression, density-dependent competition and the need to change breeding locations. By effective dispersal, organisms can enlarge their geo-graphic range and adjust the dynamic, sex ratio and gen-etic compositions of a population. Birds are one of the groups that are studied intensively by human beings. Due to their diurnal habits, diverse life history strategies and complex movement, birds are also ideal models for the study of dispersal behaviors. Certain topics of avian dispersal including sex-biased, asymmetric dispersal caused by differences in body conditions, dispersal pro-cesses, habitat selection and long distance dispersal are discussed here. Bird-ringing or marking, radio-telemetry and genetic markers are useful tools widely applied in dispersal studies. There are three major challenges regard-ing theoretical study and methodology research of dis-persal: (1) improvement in research methodology is needed, (2) more in-depth theoretical research is neces-sary, and (3) application of theoretical research into the conservation efforts for threatened birds and the manage-ment of their habitats should be carried out immediately.     

鸟类的扩散行为研究进展

扩散是生物个体之间相互远离的单线性运动,是生物的基本特征之一,对种群的分布、动态及遗传结构等方面均有重要影响.扩散有出生扩散和繁殖扩散等主要形式.动物发生扩散的主要原因包括:避免近亲繁殖、减少竞争、改变繁殖地点等.近年来,扩散已经成为鸟类学研究的前沿领域.评述了鸟类扩散行为的性别差异、体质对于扩散的影响,阐述了扩散的基本过程及栖息地选择、长距离扩散等内容,同时介绍了环志标记、无线电遥测、分子生物学等研究鸟类扩散的主要方法.展望了鸟类扩散研究的发展趋势,认为新技术和新方法的应用将成为扩散生态学家关注的重要问题,未来研究将更加重视对鸟类扩散理论问题的探讨,而对鸟类扩散行为的研究成果也会更广泛地应用于濒危物种及其栖息地的保护工作中.     

16. Dispersal of freshwater algae — a review

A survey is given on the various methods for dispersal of freshwater algae. Dispersal factors are either water or air, or organisms — from beetles, dragonflies and mammals to birds, the latter being the most important group. The question of dispersal distances is discussed, in relation to dispersal mechanisms and to the resistance of the algae to transport conditions. Man's recent importance in algal dispersal is emphasized.     

Microsatellite data show evidence for male-biased dispersal in the Caribbean lizard Anolis roquet

Dispersal is a key component of an organism's life history and differences in dispersal between sexes appear to be widespread in vertebrates. However, most predictions of sex-biased dispersal have been based on observations of social structure in birds and mammals and more data are needed on other taxa to test whether these predictions apply in other organisms. Caribbean anole lizards are important model organisms in various biological disciplines, including evolutionary biology. However, very little is known about their dispersal strategies despite the importance of dispersal for population structure and dynamics. Here we use nine microsatellite markers to assess signatures of sex-biased dispersal on two spatial sampling scales in Anolis roquet, an anole endemic to the island of Martinique. Significantly higher gene diversity (H(S)) and lower mean assignment value (mAIC) was found in males on the larger spatial sampling scale. Significant heterozygote deficit (F(IS)), lower population differentiation (F(ST)), mAIC and variance of assignment index (vAIC) was found in males on the smaller spatial scale. The observation of male biased dispersal conform with expectations based on the polygynous mating system of Anolis roquet, and contributes to an explanation of the contrasting patterns of genetic structure between maternal and biparental markers that have been reported previously in this, and other anoline, species.     

Dispersal and alternative breeding site fidelity strategies in an amphibian

Dispersal (i.e. movement from a natal or breeding site to another breeding site) is a central process in ecology and evolution as it affects the eco‐evolutionary dynamics of spatially structured populations. Dispersal evolution is regulated by the balance between costs and benefits, which is influenced by the individual phenotype (i.e. phenotype‐dependent dispersal) and environmental factors (i.e. condition‐dependent dispersal). Even though these processes have been extensively studied in species with simple life cycles, our knowledge about these mechanisms in organisms displaying complex life cycles remains fragmentary. In fact, little is specifically known about how the interplay between individual and environmental factors may lead to alternative dispersal strategies that, in turn, lead to the coexistence of contrasted site fidelity phenotypes. In this paper, we examined breeding dispersal in a pond‐breeding amphibian, the great crested newt Triturus cristatus, within usual walking distances for a newt. We took advantage of recent developments in multi‐event capture–recapture models and used capture–recapture data (946 newts marked) collected in a spatially structured population occupying a large pond network (73 ponds). We showed a high rate of breeding site infidelity (i.e. pond use) and the coexistence of two dispersal phenotypes, namely, a highly pond faithful phenotype and a dispersing phenotype. Individuals that were site faithful at time t – 1 were therefore more likely to remain site faithful at time t. Our results also demonstrated that the probability that individuals belong to one or the other dispersal phenotypes depended on environmental and individual factors. In particular, we highlighted the existence of a dispersal syndrome implying a covariation pattern among dispersal behavior, body size, and survival. Our work opens new research prospects in the evolution of dispersal in organisms displaying complex life cycles and raises interesting questions about the evolutionary pathways that contribute to the diversification of movement strategies in the wild.     

Fine‐scale genetic structure reflects sex‐specific dispersal strategies in a population of sociable weavers (Philetairus socius)

Dispersal is a critical driver of gene flow, with important consequences for population genetic structure, social interactions and other biological processes. Limited dispersal may result in kin‐structured populations in which kin selection may operate, but it may also increase the risk of kin competition and inbreeding. Here, we use a combination of long‐term field data and molecular genetics to examine dispersal patterns and their consequences for the population genetics of a highly social bird, the sociable weaver (Philetairus socius), which exhibits cooperation at various levels of sociality from nuclear family groups to its unique communal nests. Using 20 years of data, involving capture of 6508 birds and 3151 recaptures at 48 colonies, we found that both sexes exhibit philopatry and that any dispersal occurs over relatively short distances. Dispersal is female‐biased, with females dispersing earlier, further, and to less closely related destination colonies than males. Genotyping data from 30 colonies showed that this pattern of dispersal is reflected by fine‐scale genetic structure for both sexes, revealed by isolation by distance in terms of genetic relatedness and significant genetic variance among colonies. Both relationships were stronger among males than females. Crucially, significant relatedness extended beyond the level of the colony for both sexes. Such fine‐scale population genetic structure may have played an important role in the evolution of cooperative behaviour in this species, but it may also result in a significant inbreeding risk, against which female‐biased dispersal alone is unlikely to be an effective strategy.     

Causes and consequences of animal dispersal strategies: relating individual behaviour to spatial dynamics

Knowledge of the ecological and evolutionary causes of dispersal can be crucial in understanding the behaviour of spatially structured populations, and predicting how species respond to environmental change. Despite the focus of much theoretical research, simplistic assumptions regarding the dispersal process are still made. Dispersal is usually regarded as an unconditional process although in many cases fitness gains of dispersal are dependent on environmental factors and individual state. Condition-dependent dispersal strategies will often be superior to unconditional, fixed strategies. In addition, dispersal is often collapsed into a single parameter, despite it being a process composed of three interdependent stages: emigration, inter-patch movement and immigration, each of which may display different condition dependencies. Empirical studies have investigated correlates of these stages, emigration in particular, providing evidence for the prevalence of conditional dispersal strategies. Ill-defined use of the term 'dispersal', for movement across many different spatial scales, further hinders making general conclusions and relating movement correlates to consequences at the population level. Logistical difficulties preclude a detailed study of dispersal for many species, however incorporating unrealistic dispersal assumptions in spatial population models may yield inaccurate and costly predictions. Further studies are necessary to explore the importance of incorporating specific condition-dependent dispersal strategies for evolutionary and population dynamic predictions.     

Genetics of dispersal

Dispersal is a process of central importance for the ecological and evolutionary dynamics of populations and communities, because of its diverse consequences for gene flow and demography. It is subject to evolutionary change, which begs the question, what is the genetic basis of this potentially complex trait? To address this question, we (i) review the empirical literature on the genetic basis of dispersal, (ii) explore how theoretical investigations of the evolution of dispersal have represented the genetics of dispersal, and (iii) discuss how the genetic basis of dispersal influences theoretical predictions of the evolution of dispersal and potential consequences. Dispersal has a detectable genetic basis in many organisms, from bacteria to plants and animals. Generally, there is evidence for significant genetic variation for dispersal or dispersal‐related phenotypes or evidence for the micro‐evolution of dispersal in natural populations. Dispersal is typically the outcome of several interacting traits, and this complexity is reflected in its genetic architecture: while some genes of moderate to large effect can influence certain aspects of dispersal, dispersal traits are typically polygenic. Correlations among dispersal traits as well as between dispersal traits and other traits under selection are common, and the genetic basis of dispersal can be highly environment‐dependent. By contrast, models have historically considered a highly simplified genetic architecture of dispersal. It is only recently that models have started to consider multiple loci influencing dispersal, as well as non‐additive effects such as dominance and epistasis, showing that the genetic basis of dispersal can influence evolutionary rates and outcomes, especially under non‐equilibrium conditions. For example, the number of loci controlling dispersal can influence projected rates of dispersal evolution during range shifts and corresponding demographic impacts. Incorporating more realism in the genetic architecture of dispersal is thus necessary to enable models to move beyond the purely theoretical towards making more useful predictions of evolutionary and ecological dynamics under current and future environmental conditions. To inform these advances, empirical studies need to answer outstanding questions concerning whether specific genes underlie dispersal variation, the genetic architecture of context‐dependent dispersal phenotypes and behaviours, and correlations among dispersal and other traits.     

Correlations between observed dispersal capabilities and patterns of genetic differentiation in populations of four aquatic insect species from the Arizona White Mountains, U.S.A.

SUMMARY 1. Dispersal ability is an important ecological factor that can influence population structure. In an attempt to determine the extent that the pattern of genetic differentiation is correlated with dispersal ability in stream-dwelling aquatic insects, we used the amplified fragment length polymorphism (AFLP) technique to characterise genetic variation in four aquatic insect species: Gumaga griseola (Trichoptera: Sericostomatidae), Helicopsyche mexicana (Trichoptera: Helicopsychidae), Psephenus montanus (Coleoptera: Psephenidae) and Ambrysus thermarum (Hemiptera: Naucoridae). Individuals were sampled from several sites within two adjacent catchments in the Arizona White Mountains. In addition to the genetic analyses, a 20-week-long trapping study was used to determine the relative dispersal ability of adults of the four species examined.
2. We obtained hierarchical indicators of genetic differentiation for catchments, sites within catchments and sites across the region examined. Overall, average estimators of genetic differentiation ( F -statistics) were consistent with direct observations of organismal movement, although it was our direct observations on adult insect flight that permitted us to interpret our results correctly. This was because of the fact that a lack of genetic differentiation across watersheds can be interpreted in two ways.
3. In contrast to F -statistics, patterns of genetic isolation by distance for each species more clearly reflected dispersal ability, suggesting that such analytical approaches provide less ambiguous information about the importance of gene flow in the hierarchical partitioning of genetic variation in stream organisms.     

Genetic diversity and sex‐bias dispersal of plateau pika in Tibetan plateau

Dispersal is an important aspect in organism's life history which could influence the rate and outcome of evolution of organism. Plateau pika is the keystone species in community of grasslands in Tibetan Plateau. In this study, we combine genetic and field data to character the population genetic pattern and dispersal dynamics in plateau pika (Ochotona curzoniae). Totally, 1,352 individual samples were collected, and 10 microsatellite loci were analyzed. Results revealed that plateau pika possessed high genetic diversity and inbreeding coefficient in a fine‐scale population. Dispersal distance is short and restricted in about 20 m. An effective sex‐biased dispersal strategy is employed by plateau pika: males disperse in breeding period for mating while females do it after reproduction for offspring and resource. Inbreeding avoiding was shown as the common driving force of dispersal, together with the other two factors, environment and resource. In addition, natal dispersal is female biased. More detailed genetic analyzes are needed to confirm the role of inbreeding avoidance and resource competition as ultimate cause of dispersal patterns in plateau pika.     

Philopatry and natal dispersal in a sedentary population of western marsh harrier

Dispersal is a key life-history trait because it influences population dynamics and population genetic structure. From a behavioural perspective, the study of natal dispersal requires some understanding of the mechanisms that affect individual movements, because movements of an animal form a path that is continuous throughout its life. Our aim was to investigate juvenile dispersal strategies in the western marsh harrier Circus aeruginosus , between fledging and first breeding attempt (from 1 to 4 years later, depending on the sex and individual). Using radio tracking, we monitored dispersing juvenile harriers and their home-range size variations within a sedentary population in central western France from 2001 to 2007. Juvenile dispersal strategy was mainly characterized by a very high natal philopatry (i.e. birds that remained within the study area) and short-distance dispersal. All but one bird (out of 39) remained within the study area between their first winter and their first spring, and 96.0% during their first spring. The distance moved at 2 years of age was significantly larger for males than for females (3800± sd 3593 m and 935± sd 481 m for seven males and six females, respectively), in contrast to most bird species studied so far. Home-range size was not sex biased and significantly decreased with age. In addition, non-breeding birds had larger home ranges (1603± sd 2128 ha) than breeders (349± sd 185 ha). Using data obtained from other populations, juvenile marsh harrier dispersal strategies appeared to be determined by migratory status (migratory birds dispersing farther) and demographic parameters (juvenile survival or fecundity).     

Variation in dispersal mortality and dispersal propensity among individuals: the effects of age, sex and resource availability

1.  Dispersal of individuals between habitat patches depends on both the propensity to emigrate from a patch and the ability to survive inter-patch movement. Environmental factors and individual characteristics have been shown to influence dispersal rates but separating the effects of emigration and dispersal mortality on dispersal can often be difficult. In this study, we use a soil mite laboratory system to investigate factors affecting emigration and dispersal mortality.
2.  We tested the movement of different age groups in two-patch systems with different inter-patch distances. Differences in immigration among age groups were primarily driven by differences in emigration but dispersal mortality was greater for some groups. Immigration declined with increasing inter-patch distance, which was due to increasing dispersal mortality and decreasing emigration.
3.  In a second experiment, we compared the dispersal of recently matured males and females and tested the impact of food availability during the developmental period on their dispersal. Dispersal was found to be male biased but there was no significant sex bias in dispersal mortality. There was some evidence that food availability could affect emigration and dispersal mortality.
4.  These results demonstrate that both emigration and dispersal mortality can be affected by factors such as individual age and resource availability. Understanding these effects is likely to be important for predicting the fitness costs and population consequences of dispersal.     

A modeling exercise to show why population models should incorporate distinct life histories of dispersers

Dispersal is an important form of movement influencing population dynamics, species distribution and gene flow between populations. In population models, dispersal is often included in a simplified manner by removing a random proportion of the population. Many ecologists now argue that models should be formulated at the level of individuals instead of the population level. To fully understand the effects of dispersal on natural systems, it is therefore necessary to incorporate individual-level differences in dispersal behavior in population models. Here, we parameterized an integral projection model, which allows for studying how individual life histories determine population-level processes, using bulb mites, Rhizoglyphus robini, to assess to what extent dispersal expression (frequency of individuals in the dispersal stage) and dispersal probability affect the proportion of successful dispersers and natal population growth rate. We find that allowing for life-history differences between resident phenotypes and disperser phenotypes shows that multiple combinations of dispersal probability and dispersal expression can produce the same proportion of leaving individuals. Additionally, a given proportion of successful dispersing individuals result in different natal population growth rates. The results highlight that dispersal life histories, and the frequency with which disperser phenotypes occur in the natal population, significantly affect population-level processes. Thus, biological realism of dispersal population models can be increased by incorporating the typically observed life-history differences between resident phenotypes and disperser phenotypes, and we here present a methodology to do so.     

Dispersal distances of Tree Swallows estimated from continent-wide and limited-area data

ABSTRACT.   Dispersal is a critical link between organismal and population biology, yet, because of their mobility, our understanding of the causes and consequences of long-distance dispersal by birds remains poorly known. Methods used to study dispersal include (1) marking and recapturing individuals in a limited study area to estimate survival and dispersal rates, and (2) relying on volunteers to mark and recapture individuals over larger areas. We compared these two methods for measuring dispersal distances of Tree Swallows ( Tachycineta bicolor ) using recapture data from a limited-area study in New York State (the Swallow Dispersal Study, SDS) and the recapture dataset from the U.S. Bird Banding Laboratory (BBL). Analysis of BBL records revealed a difference in the dispersal distance distributions (DDD) for data reported before and after 1967. In the earlier data, 84% of the 238 records were for birds within 13.6 km of their first banding location, whereas only 22% of the 799 records in the more recent data were reported in this closest distance belt. These differences are almost certainly due to changes in reporting protocols instituted by the BBL in the mid-1960s. We corrected for recapture effort in the SDS, and, using this corrected SDS data for the proportion of birds returning in the closest distance belt and the recent BBL for the proportions of more distant movements, we created what we think is the best composite DDD for Tree Swallows. Even though dispersal distances up to 2367 km have been reported, the composite DDD indicates that fewer than 3% of birds disperse more than 100 km and that 85% disperse less than 15 km between years. Thus, our results suggest that the dispersal behavior of most individuals can be examined effectively at more local spatial scales. Studies of dispersal and mortality would be facilitated if all recaptures of banded birds were reported with accurate spatial coordinates to the Bird Banding Laboratory.     

Phoretic dispersal influences parasite population genetic structure

Dispersal is a fundamental component of the life history of most species. Dispersal influences fitness, population dynamics, gene flow, genetic drift and population genetic structure. Even small differences in dispersal can alter ecological interactions and trigger an evolutionary cascade. Linking such ecological processes with evolutionary patterns is difficult, but can be carried out in the proper comparative context. Here, we investigate how differences in phoretic dispersal influence the population genetic structure of two different parasites of the same host species. We focus on two species of host‐specific feather lice (Phthiraptera: Ischnocera) that co‐occur on feral rock pigeons (Columba livia). Although these lice are ecologically very similar, “wing lice” (Columbicola columbae) disperse phoretically by “hitchhiking” on pigeon flies (Diptera: Hippoboscidae), while “body lice” (Campanulotes compar) do not. Differences in the phoretic dispersal of these species are thought to underlie observed differences in host specificity, as well as the degree of host–parasite cospeciation. These ecological and macroevolutionary patterns suggest that body lice should exhibit more genetic differentiation than wing lice. We tested this prediction among lice on individual birds and among lice on birds from three pigeon flocks. We found higher levels of genetic differentiation in body lice compared to wing lice at two spatial scales. Our results indicate that differences in phoretic dispersal can explain microevolutionary differences in population genetic structure and are consistent with macroevolutionary differences in the degree of host–parasite cospeciation.     

Population dynamics and dispersal of Lepthyphantes tenuis in an ephemeral habitat

The population dynamics of Lepthyphantes tenuis (Blackwall) were investigated in two fields of winter wheat in Sussex, England, with the aim of attributing the major factors controlling population fluctuations. Continuous measures of changes in density, reproductive rate and dispersal were obtained using a range of methodologies, including laboratory analysis, suction trapping, rotary sampling of the aerial fauna, caging, and detailed density estimations. The resulting data were then used to determine the major causes of the observed population fluctuations and to describe the processes of dispersal and reproduction in this population.Population densities were initially very low following ploughing operations, but increased throughout the season as a result of high reproductive rates. Investigation of the reproductive potential of the spiders showed that the number of eggs per egg-sac did not vary with season, and that egg development was temperature related. There was no evidence that the number of viable eggs per egg-sac varied during the season. There were three peaks of hatchling production per year suggesting two to three generations of spiders. Dispersal was not responsible for the major changes in field density throughout the season although dispersal activity was high for this species. Dispersal activity increased with age and was highest in females. Dispersal activity as a ratio of activity/field density for females, males, sub-adults, immatures and hatchlings was 4:2:3:1:1.Aerial dispersal is only possible under suitable weather conditions. It was found that female dispersal was correlated with weather conditions far more strongly than other population groups. Calculations showed that under suitable weather conditions (e.g., 25% of the time being suitable for dispersal), almost 4% of the adult females could be expected to leave the population daily. The overall effect is therefore to displace individuals from the population but to have little effect on densities. Dispersal in other stages was controlled by the suitability of weather conditions but also by other, undetermined factors. It is postulated that L. tenuis has a life history strategy whereby suitable habitats act as sources of spiders, mainly females, which are continually involved in dispersal. Dispersal in other population groups may be triggered by factors such as the avoidance of adverse conditions. This type of life-history strategy is typical of organisms, such as weeds, that are successful in ephemeral habitats and may indicate that this species originally evolved in unpredictable habitats such as dry river beds or coastal areas.     

Inferring sex-biased dispersal from population genetic tools: a review

Sex-biased dispersal, where individuals of one sex stay or return to their natal site (or group) to breed while individuals of the other sex are prone to disperse, is a wide-spread pattern in vertebrate organisms. In general, mammals exhibit male-biased dispersal whereas birds exhibit female-bias. Dispersal estimates are often difficult to obtain from direct field observations. Here we describe different methods for inferring sex-specific dispersal using population genetic tools and discuss the problems they can raise. We distinguish two types of methods: those based on bi-parental markers (eg comparison of male/female relatedness, F(st) and assignment probabilities) and those relying on the comparison between markers with different modes of inheritance (eg mtDNA markers and microsatellites). Finally, we discuss statistical problems that are encountered with these different methods (eg pseudoreplication, problems due to the comparison of distinct markers). While the genetic methods to detect sex-biased dispersal are now relatively well developed, their interpretation can prove problematic due to the confounding effects of factors such as the mating system of the species. Moreover, the relative power of these methods is not well known and requires further investigation.     

Dispersal, interpatch movements, and survival in a shrubland breeding bird community

ABSTRACT Dispersal events can affect the distribution, abundance, population structure, and gene flow of animal populations, but little is known about long‐distance movements due to the difficulty of tracking individuals across space. We documented the natal and breeding dispersal of shrubland birds among 13 study sites in a 1000 km² area in southeastern Ohio. In addition, we radio‐marked and tracked 37 adult males of one shrubland specialist, the Yellow‐breasted Chat (Icteria virens). We banded 1925 juveniles and 2112 adults of nine shrubland species from 2002 to 2005. Of these, 33 (1.7%) juveniles were encountered in subsequent years (2003–2006) as adults (natal dispersal) and 442 (20.9%) birds initially banded as breeding adults were re‐encountered in subsequent years (breeding dispersal). Apparent survival of juvenile shrubland birds on their natal patches was 0.024 (95% CI 0.016–0.036). After accounting for the probability of detection, we found that 21% of birds banded as juveniles and recaptured as adults returned to their natal patches, whereas 78% of adult birds showed fidelity to the patch where they were originally captured. Moreover, natal dispersers tended to move farther than breeding dispersers (corrected natal median = 1.7 km ± 0.37; corrected breeding median = 0.23 km ± 0.10). We used our estimates of natal dispersal and annual apparent survival to estimate true survival at 0.11 (95% CI 0.07–0.18) for juveniles in their first year. However, this estimate was only applicable for birds dispersing within 7 km of their natal patches. Interpatch movements of radio‐marked Yellow‐breasted Chats were not uncommon, with 13 of 37 males located in more than one habitat patch. Overall, we observed low natal philopatry, but high adult site fidelity for shrubland birds in our study area. Considering the frequency of short‐distance movements observed (median = 531 m, range = 88–1045 m), clustering of patches within 1 km might facilitate use of shrubland habitat.     

A comparison of techniques for assessing dispersal behaviour in gundis: revealing dispersal patterns in the absence of observed dispersal behaviour

Knowledge of the dispersal status of group members is important to understanding how sociality may have evolved within a species. I assessed the effectiveness of four techniques for elucidating dispersal behaviour in a rock-dwelling rodent ( Ctenodactylus gundi ) with small group sizes (2–10 animals): genetic parentage assignment, haplotype data and kinship analyses, assignment testing, and F -statistics. The first two methods provided the greatest insight into gundi dispersal behaviour. Assignment testing and F -statistics proved of limited use for elucidating fine-scale dispersal, but could detect large-scale patterns despite low sex-biased dispersal intensity (1.9 : 1) because of moderate genetic differentiation among groups ( F _ST = 0.10). Findings are discussed in light of current dispersal theory. In general, gundi dispersal is plastic, and seems to be dependent on body weight (for males), group composition, and scale of analysis (total dispersal events recorded within the population were almost twice the immigration rate into the population). Most groups were comprised of a single matriline and one immigrant male. Immigrant rather than philopatric males bred with group females. Dispersal among groups was male-biased, but dispersal or philopatry could occur by either sex. During a drought, both sexes delayed dispersal and cooperative social units formed. Whether such behaviour resulted directly from the drought or not remains unclear, however, since comparative information was not available from nondrought years. Combining fine-scale analyses with information on large-scale patterns provided substantial insight into gundi dispersal behaviour despite the limited movement of animals during a drought, and may prove useful for elucidating dispersal behaviour in other social animals.