Stepping stones of life: natal dispersal in the group-living but noncooperative speckled warbler

In most cooperatively breeding birds the offspring of one sex, usually male, delays dispersal to remain on the natal territory and helps its parents to rear subsequent young. Thus delayed dispersal could be the first step in the evolution of cooperative breeding. We studied natal dispersal in a population of the group-living speckled warbler, Chthonicola sagittata, based on observations of a colour-banded population over 3 years. Unlike other group-living members of the Acanthizinae, all juvenile males in this population dispersed to settle on foreign territories as subordinates, which do not help rear the young. Speckled warblers showed all the life history traits that are thought to result in a saturated habitat and lead to delayed dispersal: they were sedentary, had high adult survival and had a male-biased sex ratio. However, they differed from other acanthizids in occurring at low density (0.18 birds/ha) on large breeding territories (6-12 ha), with a maximum of two males per territory. This may allow subordinates to live on foreign territories yet avoid aggression from dominants. A benefit of dispersal is that it provides an additional route to gaining a breeding vacancy. Dispersers can acquire vacancies on their new territory or on a neighbour's, but incest avoidance would be likely to constrain nondispersing males to neighbours' territories. A model of relative lifetime success showed that the survival benefits of natal philopatry are unlikely to outweigh this benefit of dispersal.     

The first UK survey and population estimate of breeding Snow Bunting Plectrophenax nivalis

Capsule: The first national survey for Snow Bunting Plectrophenax nivalis in the UK was carried out in 2011 and estimated the breeding population at 60 territories (95% confidence intervals?=?48–83).

Aims: To estimate breeding population size for Snow Buntings in the UK by surveying all sites with a history of breeding season occupation.

Methods: Surveys were carried out in June 2011 to detect males on territory at sites where Snow Bunting had been recorded during the breeding season since 1970. Each site was visited at least once during the survey period; suitable habitat was searched and vantage point watches were conducted in order to detect singing males. Repeated visits to a sample of sites allowed a correction factor to be calculated in order to account for birds undetected during surveys.

Results: In 2011, the number of Snow Bunting breeding in the UK (including adjusting for imperfect detection) is a minimum of 60 territories (95% CI?=?48–83) using confirmed and probable breeding records of males. A less conservative estimate of 99 territories (95% CI?=?88–114) results from including all records of males in suitable habitat. The vast majority of the population was found in the Cairngorm region, with isolated records in the north and west Highlands.

Conclusion: The results of the 2011 survey are consistent with well-informed estimates of the Snow Bunting population made previously. This work provides a baseline and repeatable fieldwork and analytical methods enabling future change in the population to be quantified more rigorously.     

Routes to breeding in cooperatively breeding pied babblers Turdoides bicolor

In cooperatively breeding and other family living species, there are often more individuals of reproductive age than available breeding positions. Asking how individuals attain reproductive status is therefore crucial if we are to understand the selection pressures that operate in these groups. Here, we present data on routes to breeding in pied babblers Turdoides bicolor, cooperatively breeding passerines from the Kalahari Desert. Individuals of both sexes remained on the natal territory into adulthood, despite being relatively unlikely to breed there. Instead, individuals seemed to use the natal territory as a base to monitor the availability of breeding positions elsewhere. Both sexes were most likely to attain breeding status by moving into vacant breeding positions on non‐natal territories, although females also occasionally seized breeding positions by overthrowing breeding females on foreign territories. We discuss these patterns in the context of existing theoretical and empirical data.     

Age-dependent prospecting and recruitment to a breeding colony of Short-tailed Shearwaters Puffinus tenuirostris

In a small colony of Short-tailed Shearwaters Puffinus tenuirostris , monitored annually since 1947, many of the young ringed as nestlings returned to their natal colony for one or more years before breeding for the first time. These 'prospectors' were first recorded at 4.1 ± 0.1 (range 2–7) years old; they started breeding at 7.0 ± 0.2 (4–14) years old. Overall, 31% of all prospectors bred on their natal island with no significant annual variation in this proportion. However, 8% of all natal recruits started breeding without having been recorded prospecting and bred first when significantly younger (5.6 ± 0.4 years old) than those first recorded prospecting. Shearwaters which subsequently bred at their natal colony started prospecting when significantly older (4.3 ± 0.1) than those that did not breed at their natal colony (4.0 ± 0.1 years). Non-natal recruits spent significantly less time prospecting (1.0 ± 0.1 years) than prospectors born on the island (1.9 ± 0.1 years). The shearwaters appeared to become progressively more faithful to the colony during their prospecting period.     

Sex-bias and timing of natal dispersal in cooperatively breeding Puff-throated Bulbuls Alophoixus pallidus

While natal dispersal can have a significant impact on population dynamics, it is typically difficult to quantify. We investigated timing of natal dispersal of the cooperatively breeding Puff-throated Bulbul Alophoixus pallidus in a tropical evergreen forest by modelling the probability of staying in or dispersing from their natal territory whilst taking into account the effects of sex, group size, and the presence of helper(s). Birds did not disperse until the beginning of and during the breeding season following the hatching year. Dispersal was strongly female-biased both in frequency and distance: most females (95%) dispersed away from their natal territories, and of those relocated, traversed 2–7 territories. In contrast, 50% of males remained in the natal territory as helpers in their second year, while relocated dispersing males crossed 1–2 territories. Natal dispersal was not influenced by either group size or the presence of helpers. Males that fledged earlier in the breeding season exhibited higher rates of philopatry than the males that fledged later, but no correlation between fledging date and philopatry was observed in females. The probability of staying in the natal territory during the second year was 0.58 ± 0.14 SE and 0.05 ± 0.04 for males and females, respectively. These findings may add to our understanding of how natal dispersal can reflect social patterns and kin structure in cooperative breeding species from a little-studied tropical forest region.     

NATAL DISPERSAL AND POPULATION STRUCTURE IN A MIGRATORY SONGBIRD,THE INDIGO BUNTING

Male and female indigo buntings (Passerina cyanea) were equally likely to return and breed in their natal areas. The distances and number of territories between natal and breeding sites were similar between the sexes. The breeding site was not limited by prior occupation of sites by breeding adults closer to the natal territory. Dispersal distances were independent of whether parents or siblings of either sex returned in the same year. Variation in distance within the natal area appeared to be independent of local population density, social competition, active kin recognition, and avoidance of incest, but was affected by date of birth. The local distribution of dispersal distances approximated a neutral model with a decreasing probability of settling with distance from the natal site. A population inbreeding coefficient ΔF of 0.01 was estimated from known genealogies and matings. The proportion of nestlings recaptured in a later year on their natal area was 1.65% of 1,212 nestlings at the George Reserve and 8.78% of 1,332 nestlings at Niles. Locally born birds comprised 1.6% and 13.0% of the breeding population in areas of 10 and 4 km². Evidently most buntings settle and breed more than 2 km from their natal site. The results are inconsistent with predictions of social and avoidance-of-inbreeding hypotheses that are based on the local natal demographic environment. The results are consistent with a model of neutral dispersal within a genetically open population.     

Sex biased natal dispersal in a closed, saturated population of Seychelles warblers Acrocephalus sechellensis

The distances that individuals disperse, from their natal site to the site of first breeding and between breeding sites, have important consequences for the dynamics and genetic structure of a population. Nearly all previous studies on dispersal have the problem that, because the study area encompassed only a part of the population, emigration may have been confounded with mortality. As a result long-distance dispersers may have been overlooked and dispersal data biased towards short distances. By studying a virtually closed population of Seychelles warblers Acrocephalus sechellensis we obtained almost unbiased results on several aspects of dispersal. As in the majority of other avian species, natal dispersal distance was female biased in the Seychelles warbler. Female offspring also forayed further from the natal territory in search of breeding vacancies than male offspring. The sex bias in natal dispersal distance did, however, depend on local breeding density. In males, dispersal distance decreased as the number of territories bordering the natal territory increased, while in females, dispersal distance did not vary with local density. Dispersal by breeders was rare and, unlike in most species, distances did not differ between the sexes. We argue that our results favour the idea that the sex bias in natal dispersal distance in the Seychelles warbler is due to inbreeding avoidance and not resource competition or intrasexual competition for mates.     

Floater interference reflects territory quality in the Spanish Imperial Eagle Aquila adalberti: a test of a density‐dependent mechanism

We report on an 11‐year study of floater interference in a population of Spanish Imperial Eagles Aquila adalberti. We analysed changes over the years in the productivity of 15 territories to test predictions of two hypotheses of density‐dependent productivity in relation to the presence of floaters (birds without territories). According to the ‘interference' hypothesis, the frequency of intrusion by floaters increases with density, resulting in a decrease in productivity. Thus, in a high‐density population a negative relationship between floater intrusions and productivity of the territory is expected. In contrast, under the ‘habitat heterogeneity' hypothesis, as density increases a higher proportion of individuals is forced to occupy lower quality habitats. Support of this hypothesis requires that floaters detect differences in quality among territories and preferentially visit the better quality territories. Consequently, a positive relationship between floater intrusions and productivity is expected. Results showed that floaters tended to visit their natal area at the beginning of the breeding season. Among floater Eagles, males made significantly more intrusions per day than did females, but females stayed in the natal population for longer each year than males. Floater intrusions and productivity were highly positively correlated, supporting the ‘habitat heterogeneity' hypothesis; individuals were apparently able to assess the quality of a territory and, at the frequencies observed, their interference with the breeding pair had no obvious negative effect on productivity.     

Statilia maculata (Thunberg, 1784) – the first invasive praying mantis (Mantodea,Mantidae) in the fauna of Russia

Summary

Recent years have seen an increasing number of alien praying mantis species being introduced and establishing populations across Europe. Here we add to this count, reporting a stable and spreading population of an Asian species, Statilia maculata (Thunberg, 1784), in Krasnodar Krai of Southern Russia. This is the first introduced praying mantis species in the Russian fauna and the first representative of the genus Statilia Stål, 1877 in Europe. We review what is known about biology of this species and provide diagnostic characters to distinguish nymphs, adults and oothecae from native and introduced European species of praying mantis. Our attempts at captive breeding identify humidity as one of the most important factors limiting possible spread of S. maculata. Invasion to neighbouring territories and other countries with a humid subtropical climate remains a very real possibility with an unknown outcome for local ecosystems.     

Turnover and dispersal in a Peregrine Falco peregrinus population

In south Scotland, most Peregrines returned to the same territories to breed in successive years, though a few females changed territory from one year to the next.
Annual mortality among breeding birds was at most 9% among females (or 11% in both sexes combined). There may have been considerable annual variation, however, and excluding one exceptional year out of five reduced the estimate for females to 7%. These estimates are maxima, but are still considerably lower than those obtained from ring recoveries of dead birds reported by members of the public.
Among trapped birds, four males first bred at age two years, one at three and another at four or five; two females first bred at one year, 13 at two years old and one at three. Five other females which were seen to be in first-year plumage but were not trapped, also laid eggs, and 12 other such paired females held territory but did not lay. Only one paired male held territory in first-year plumage.
In their movements between natal and breeding territories, some females moved further than males, with median distances of 83 and 58 km respectively. In addition, of birds trapped breeding in the study area, a greater proportion of the males than of the females had been born locally, despite an equal sex ratio among fledglings; this was also consistent with a greater dispersal of females. In general, Peregrines made much longer movements in their first year of life than subsequently. Movements were in any direction.     

Dispersal strategies in Tasmanian native hens (Gallinula mortierii)

Individuals in cooperatively breeding species face a complexset of decisions when they reach reproductive maturity. Duringan 8-year study, we examined the histories of 214 Tasmaniannative hens (Gallinula mortierii) from hatching to examinethe strategies they used to acquire breeding positions andthe reproductive success they experienced in those breedingpositions. Two-thirds of young delayed dispersal from theirnatal groups for at least a year. Ecological constraints werea partial cause of delayed dispersal; high-quality territorieswere rare and remained occupied due to high adult survivorship.There were also clear benefits of philopatry. Individuals thatinherited breeding positions on their natal territories gainedbetter quality positions and experienced higher reproductivesuccess in their first breeding attempts than did individualswho dispersed to other groups. Multivariate analyses showedthat the method of acquisition of breeding positions was theonly factor significantly related to the quality of the breedingpositions attained. Males were more likely to inherit breeding positions in their natal groups than were females. The compositionsof individuals' natal groups had no effect on whether theyinherited breeding positions or dispersed. In contrast, thecompositions of groups did appear to affect whether other birdsdispersed into them, with birds rarely moving into groups thatcontained breeders or nonbreeders of the same sex as the potential dispersers. Short-term removals of breeders confirmed this finding.These results suggest that both ecological constraints andbenefits of philopatry explain delayed dispersal in this species.     

Dispersal and philopatry in the European badger, Meles meles

In comparison with other carnivores, European badgers, Meles meles L., show an unusually high degree of natal philopatry. In this paper, we present data on temporary and permanent movements between groups, in both male and female badgers, in a moderately high density population. A relatively small proportion of males dispersed, alone, to neighbouring territories. Dispersing males were larger than those remaining in their natal groups, and following dispersal they had higher testosterone titres and maintained testicular activity for a greater part of the year. Circumstantial evidence suggests that immigrants were the principal breeding males in their new territories. Dispersal was slightly more common in females, which dispersed away from large groups, where their chances of breeding were relatively low. Females dispersed in coalitions of 2–3, over longer distances, to territories occupied by single females. Resident females disappeared following the arrival of the immigrants, suggesting that territory 'takeovers' may have occurred. Members of both sexes also made temporary 'visits' to neighbouring territories, probably to obtain extra-group matings. Comparison with other badger populations suggests that the frequency of male dispersal declines at high population densities. In contrast, there is no effect of density on female dispersal, which occurs only rarely in some other populations. We suggest that the pattern of female/female competition is too complex to be explained solely in terms of variation in population density.     

Dispersal influences genetic and acoustic spatial structure for both males and females in a tropical songbird

Animals exhibit diverse dispersal strategies, including sex‐biased dispersal, a phenomenon common in vertebrates. Dispersal influences the genetic structure of populations as well as geographic variation in phenotypic traits. Patterns of spatial genetic structure and geographic variation may vary between the sexes whenever males and females exhibit different dispersal behaviors. Here, we examine dispersal, spatial genetic structure, and spatial acoustic structure in Rufous‐and‐white Wrens, a year‐round resident tropical bird. Both sexes sing in this species, allowing us to compare acoustic variation between males and females and examine the relationship between dispersal and song sharing for both sexes. Using a long‐term dataset collected over an 11‐year period, we used banding data and molecular genetic analyses to quantify natal and breeding dispersal distance in Rufous‐and‐white Wrens. We quantified song sharing and examined whether sharing varied with dispersal distance, for both males and females. Observational data and molecular genetic analyses indicate that dispersal is female‐biased. Females dispersed farther from natal territories than males, and more often between breeding territories than males. Furthermore, females showed no significant spatial genetic structure, consistent with expectations, whereas males showed significant spatial genetic structure. Overall, natal dispersal appears to have more influence than breeding dispersal on spatial genetic structure and spatial acoustic structure, given that the majority of breeding dispersal events resulted in individuals moving only short distances. Song sharing between pairs of same‐sex animals decreases with the distance between their territories for both males and females, although males exhibited significantly greater song sharing than females. Lastly, we measured the relationship between natal dispersal distance and song sharing. We found that sons shared fewer songs with their fathers the farther they dispersed from their natal territories, but that song sharing between daughters and mothers was not significantly correlated with natal dispersal distance. Our results reveal cultural differences between the sexes, suggesting a relationship between culture and sex‐biased dispersal.     

5. GENERAL NOTES

Olive Thrushes Turdus olivaceus olivaceus in Grahamstown, South Africa, were present in their territories throughout the year. Mist-net captures showed no seasonal fluctuation in the population density of adults. The breeding season had a main peak from August to November and a minor peak in April. Song output was greatest at the beginning of the breeding periods, when territorial boundaries were most keenly contested. There was a positive correlation between seasonal variation in breeding intensity and song output. The adult survival rate was estimated at 80%, and 56% of the fledglings were alive in their natal territories at the age of independence. In this study area, only females built nests and brooded nestlings. Only males sang. Both males and females defended their territories.     

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.     

Dispersal,ranging and settling behaviour of Marsh Tits Poecile palustris in a fragmented landscape in lowland England

Capsule Natal dispersal was rapid and distances were short. Winter ranging and breeding dispersal were limited. Few birds undertook large movements.

Aims To investigate the natal and breeding dispersal of Marsh Tits, including the timing of dispersal movements.

Methods Nestlings, juveniles and adults were ringed and searched for over 4500 ha during summer, autumn–winter, and spring over six years. Dispersal distances were measured as metric distances and multiples of territory widths. Ranging distances were compared with dispersal distances.

Results Median distances of natal dispersal were 2.6 territory widths for males (704.5 m) and 3.1 territory widths for females (1065.0 m). Median distances of breeding dispersal were 0.2 territory widths for males and females (58.6 and 53.1 m respectively). Most natal dispersal was completed soon after independence, with further movement in spring. Breeding dispersal was also detected during these periods. Median ranging distances were short, and some winter floaters were identified.

Conclusion Marsh Tits had short dispersal distances, with most dispersal activity occurring in June. Results suggested that dispersal behaviour was sensitive to habitat fragmentation, resulting in poor settling success outside of the natal wood. Habitat fragmentation may, therefore, be a contributory factor in the decline of the Marsh Tit population in Britain.     

Hatching date influences age at first reproduction in the black-headed gull

In long-lived colonial birds, age at recruitment is an important life-history character. Variation in this parameter may reflect differences in several factors, including competitive ability and breeding strategies. Further, these differences may be due to timing of hatching (for instance through differences in competitive ability). We investigated the age of first-time breeders in relation to hatching date in a black-headed gull Larus ridibundus colony situated in central France, from 1979 to 1993. Age at first breeding was estimated for four groups of individuals (total n=550) according to their hatching date, using a recent capture-recapture methodology which allowed us to estimate recruitment rate without the limiting assumptions of methods relying on simple return rates. The age at first breeding was negatively correlated with the hatching date of individuals: individuals hatched earlier in the season started breeding at a younger age than individuals born later. Proportionally more 2-year-old late-hatched individuals were seen breeding on small peripheral colonies than young early-hatched individuals. This difference disappeared after age 3 years. These results strongly suggest that individuals hatched late in the season start to breed on peripheral colonies before recruiting to their natal colony. A difference of few weeks in hatching date has consequences which can last for several years.     

Genetic monogamy in single-male groups of acorn woodpeckers, Melanerpes formicivorus

Acorn woodpeckers have one of the most complex social systems of any bird species. Breeding units range in size from monogamous pairs to groups of 15 birds that include multiple breeding males and females as well as nonreproductive helpers-at-the-nest. Groups form when young remain at their natal nest to help their parents breed or when single-sex coalitions of siblings disperse to fill a reproductive vacancy on another territory. Plural breeding and helping behaviour are thought to be favoured through indirect fitness benefits for individuals that would otherwise be unable to breed due to a shortage of reproductive vacancies on territories with acorn stores. We report the results of multi-locus DNA fingerprinting of 51 offspring from 18 nests of 16 socially monogamous pairs of acorn woodpeckers. If socially monogamous females mate outside the pair-bond, indirect fitness benefits for cobreeders and helpers will be significantly reduced. Monogamous pairs accounted for all but one of the 51 offspring we tested; the single exception was apparently sired by the putative father, but the putative mother was excluded from maternity. Our results indicate that individuals remaining on their natal territories as helpers are generally the genetic offspring of the pair they help. They also suggest that single-sex coalitions offspring dispersing together from nests of socially monogamous pairs will be full-siblings.     

Role of breeding and natal movements in lifetime dispersal of a forest‐dwelling rodent

The lifetime movements of an individual determine the gene flow and invasion potential of the species. However, sex dependence of dispersal and selective pressures driving dispersal have gained much more attention than dispersal at different life and age stages. Natal dispersal is more common than dispersal between breeding attempts, but breeding dispersal may be promoted by resource availability and competition. Here, we utilize mark–recapture data on the nest‐box population of Siberian flying squirrels to analyze lifetime dispersal patterns. Natal dispersal means the distance between the natal nest and the nest used the following year, whereas breeding movements refer to the nest site changes between breeding attempts. The movement distances observed here were comparable to distances reported earlier from radio‐telemetry studies. Breeding movements did not contribute to lifetime dispersal distance and were not related to variation in food abundance or habitat patch size. Breeding movements of males were negatively, albeit not strongly, related to male population size. In females, breeding movement activity was low and was not related to previous breeding success or to competition between females for territories. Natal philopatry was linked to apparent death of a mother; that is, we did not find evidence for mothers bequeathing territories for offspring, like observed in some other rodent species. Our results give an example of a species in which breeding movements are not driven by environmental variability or nest site quality. Different evolutionary forces often operate in natal and breeding movements, and our study supports the view that juveniles are responsible for redistributing individuals within and between populations. This emphasizes the importance of knowledge on natal dispersal, if we want to understand consequences of movement ecology of the species at the population level.     

Territorial Organization of the White Fronted Bee-eater in Kenya

White fronted bee-eaters (Merops bullockoides) live in extended family clans that aggregate to roost and nest in large colonies. Members of a given clan also share a common foraging territory, spatially segregated from the colony, to which they commute daily. The size of this foraging territory is positively related to clan size. Clan foraging territories are divided into a number of loosely overlapping foraging home ranges (FHRs), each occupied by an individual or mated pair of birds. Bee-eaters feed solitarily, flycatching to snap up large insects from widely dispersed perches. Each bird tolerates intrusion on its FHR by various members of its own clan, but aggressively excludes individuals belonging to other clans. Birds defend only their own FHR; however, because of the high amount of FHR overlap, the result is a loose form of group defense of the larger clan feeding area. For this reason we refer to the system as one of clan foraging territories. Birds occupying clan foraging territories located more than 1.5 to 2 km from a colony temporarily abandoned them while feeding nestlings. At such times, these birds provisioned their young by foraging near the colony. Birds that abandoned territories foraged less efficiently, provisioned nestlings at a lower rate, and had lower breeding success than did birds that continued use of their foraging territories. A model is developed relating territory abandonment to the energetics of central place foraging. Bee-eaters typically shift colony locations between successive breeding seasons. Foraging territory locations, in contrast, remain largely stable, resulting in large and unpredictable changes in the quality of any given foraging territory across years (quality being defined as distance from the currently active nesting colony). When a pair bond forms in bee-eaters, one member typically remains in its natal clan while the other moves into the clan of its partner. At this time, the new pair also establishes its own FHR, generally located within or on the periphery of the clan foraging territory of the natal member. The result of this settlement pattern is that white fronted bee-eaters live their lives spatially surrounded by members of their natal or their matrimonial clan. This, in turn, increases the likelihood of both mutualistic and nepotistic interactions among clan members. Such benefits include shared territory defense, enhanced security against predation, and maintenance of close social bonds with potential helpers. We hypothesize that the adaptive value of clan foraging territories lies in long-term familiarity with a foraging area. Such familiarity was demonstrated to lead to improved foraging efficiency and hypothesized to provide both increased security from predation and a more accurate means of monitoring temporal changes in environmental quality. The system of clan foraging territories found in white fronted bee-eaters differs from the all-purpose group territories of most other cooperative breeders studied to date in two important ways. First, foraging territories were not limiting in the sense of restricting dispersal and “forcing” offspring to remain with their natal clans. Unoccupied areas of seemingly suitable habitat were present throughout the study area at all times. Birds also showed no tendency to expand their boundaries or move into areas vacated when neighboring clans decreased in size or died off. Second, breeding status and foraging territory ownership are not linked in Merops bullockoides. All pairs defended foraging areas, yet only about 3/4 of them bred in any given year. This percentage did not differ significantly between pairs occupying high quality foraging territories (located near the active nesting colony) and pairs forced to abandon low quality foraging territories located more distantly. We conclude that foraging territories are not a critical ecological constraining factor for white fronted bee-eaters in Kenya.