Natal Colony Research Articles

Adult and pre-breeding survival estimates of the Whiskered Tern Chlidonias hybrida breeding in southern Poland

We present the first-ever survival estimates of the Whiskered Tern Chlidonias hybrida, based on the analysis of capture–recapture data (403 adults and 1,484 chicks ringed) collected between 1993 and 2011 in an increasing breeding population in southern Poland. Data were modelled using multistate models with an unobservable state, accounting for the period during which young terns remain at their winter quarters. Model-averaged pre-breeding and breeding survival were estimated to be 0.54 [standard error (SE) 0.28] and 0.80 (SE = 0.05), respectively. All models were in agreement that the relative proportion of breeders was nearly zero in the second calendar year, increasing to reach values close to 0.8 in the fifth calendar year, which confirms the observation of a much delayed maturation of the Whiskered Tern. Our data indicate that most Whiskered Tern start to breed about 1 year earlier than members of genera Sterna and Onychoprion. However, the precision of the estimates for the parameter describing the transition probability from the unobservable pre-breeding to the observable breeding state was extremely poor; therefore, these estimates should be treated as tentative until more data are collected. The three best-supported models indicated significant annual variation in recapture probability. The results also suggested that forced exchange of breeding colonies is frequent in the study area; consequently, a large proportion of birds ringed as chicks are breeding in colonies other than their respective natal colony. This exchange is best explained not by the trapping and ringing activity but by human management of the environment, such as water level changes in dam reservoirs and carp Cyprinus carpio farming at fish ponds, both of which result in breeding habitats becoming unstable and periodically unavailable, possibly forcing birds to change breeding sites.

Readers and Writers in Colonial Natal (1843–1910)

The purpose of this essay is to present a broad outline of ways in which literary or imaginative texts were circulated and consumed in Natal Colony in the years 1843–1910. It shows how, at least initially, the majority of these texts originated abroad, but how increasingly colonials began to supply their own literary marketplace. While recognising that the thematic preoccupations of Natalian writers potentially offer a fruitful field for further research, these are not my immediate concern. My essay will be concerned instead with reading practices within the colony and those writing practices that aimed to satisfy a local appetite for imaginative texts.

Learnt information in species-specific ‘trail pheromone’ communication in stingless bees

Specificity in biological signalling systems is often important to keep information private. Foragers of several species of stingless bees deposit chemical marking signals to guide nestmates to food sources. The markings show species- and colony-specific compositions and primarily attract a bee's nestmates. An interesting question is whether the bees innately recognize specific trail markings or learn their particular composition from nestmates. To investigate this question, we tested whether Scaptotrigona pectoralis and Scaptotrigona subobscuripennis workers taken from their mother colonies and workers that emerged from combs transferred to foster colonies of the congeneric species are attracted to the marking compounds of workers from their natal colony or from the foster colony. A significant majority of workers were attracted to extracts prepared from foragers of the nest they inhabited, regardless of whether this was the original mother or the congeneric foster colony. Thus, the preference of stingless bee workers for specific food-marking scent mixtures is not innate, but is influenced by the odour they experience within their colony. Despite marked differences in the chemical composition of the scent marks in labial gland secretions of the two investigated species they also shared some main components. We hypothesize that recruitment trail information in stingless bees is composed of one or a few key pheromone compounds acting in conjunction with an additional signature mixture that is species and colony specific and must be learnt by recruited workers.

Migration and dispersal patterns of bats and their influence on genetic structure

Abstract Bats are important ecosystems service providers, make a significant contribution to biodiversity and can be important pests and disease vectors. In spite of this, information on their migration and dispersal patterns is limited. In temperate bats, migration is most evident in females. This reflects seasonal differences in their habitat requirements, and the fact that seasonally suitable sites can be geographically distant. Tropical bats mainly migrate to track variation in food availability. Little direct information is available on the patterns and drivers of bat dispersal, although drivers may include mate competition and inbreeding avoidance. In many temperate species, differential energy requirements and local resource competition among the sexes drive sexual segregation in the summer: females remain philopatric to their natal region, and frequently to their natal colony, while males disperse. In contrast, many tropical Pteropodidae form single‐male/multi‐female groups in which local resource defence contributes to female‐biased or all‐offspring dispersal from the natal site. Population genetic studies are the most common source of evidence used to infer the spatial dynamics of bats. As expected, migratory species tend to have less genetically structured populations over large geographical scales due to mating outside of breeding areas, weak migratory connectivity and long‐distance movements. In contrast and as expected, populations of sedentary species tend to be more differentiated at smaller geographical scales. Despite this general pattern, a range of factors, including historical events, dispersal capabilities, and behavioural, ecological and geographical barriers, are implicated in the genetic partitioning of bat populations, irrespective of movement patterns. These factors limit the study of bat movements using only genetic methods. Combining population genetics with other methods, such as mark–recapture, tracking or stable isotope analysis, should provide more insight into the movements of these ecologically and economically important species.

Molecular Evidence for Gender Differences in the Migratory Behaviour of a Small Seabird

Molecular sexing revealed an unexpectedly strong female bias in the sex ratio of pre-breeding European Storm Petrels (Hydrobates pelagicus), attracted to playback of conspecific calls during their northwards migration past SW Europe. This bias was consistent across seven years, ranging from 80.8% to 89.7% female (mean annual sex ratio ± SD = 85.5% female ±4.1%). The sex ratio did not differ significantly from unity (i.e., 50% female) among (i) Storm Petrel chicks at a breeding colony in NW France, (ii) adults found dead on beaches in Southern Portugal, (iii) breeding birds attending nest burrows in the UK, captured by hand, and (iv) adults captured near a breeding colony in the UK using copies of the same sound recordings as used in Southern Europe, indicating that females are not inherently more strongly attracted to playback calls than males. A morphological discriminant function analysis failed to provide a good separation of the sexes, showing the importance of molecular sexing for this species. We found no sex difference in the seasonal or nocturnal timing of migration past Southern Europe, but there was a significant tendency for birds to be caught in sex-specific aggregations. The preponderance of females captured in Southern Europe suggests that the sexes may differ in migration route or in their colony-prospecting behaviour during migration, at sites far away from their natal colonies. Such differences in migration behaviour between males and females are poorly understood but have implications for the vulnerability of seabirds to pollution and environmental change at sea during the non-breeding season.

Carry‐over effects of spring hunt and climate on recruitment to the natal colony in a migratory species

Summary In long‐lived species, temporal variation in recruitment, defined as the entry of new individuals into the breeding population, can have a large effect on population growth rate. While hunting, as a management tool, is generally expected to control population size via increased mortality, it may also act by affecting recruitment. Although the impact of hunting on survival is well studied, less attention has been paid to the non‐lethal impacts of hunting on recruitment. To control the population size of the greater snow goose Chen caerulescens atlantica, an overabundant arctic‐nesting species, a spring hunting season was implemented from 1999 onwards in addition to the traditional autumn and winter hunting seasons. We investigated the potential carry‐over effect of spring hunting on recruitment of females to their natal colony on Bylot Island, Nunavut, Canada from 1992 to 2005 while accounting for other potential confounding factors, primarily climatic effects. We applied a multistate capture‐Mark‐Recapture recruitment model to a dataset of known‐age individuals (n = 12 100), combining live recaptures at the breeding colony with dead recoveries from hunters. Annual variation in recruitment probability was best explained by spring hunt and a synthetic variable combining the climatic conditions experienced during migration (extreme values of the North Atlantic Oscillation index) with conditions upon arrival at the breeding grounds (snow cover). This model accounted for 58% of the temporal variation in recruitment, while the harvest rate or the climatic index taken alone accounted for 38% each. In the year with the highest spring hunting pressure (adult harvest rate ≈6%), recruitment was reduced by up to 50% compared to years with no hunt and similar average climatic conditions. Synthesis and applications. We conclude that there was a negative impact of the spring hunt not only on survival but also on recruitment in greater snow geese. These non‐lethal effects of hunting must be considered in management decisions aimed at controlling overabundant populations where recruitment is an important driver of population growth, as occurs in geese. Our study is also relevant to other situations such as in threatened species still exposed to hunting, as consideration of non‐lethal effects of hunting may be critical for their conservation.

Laying date, body mass and tick infestation of nestling tropical Roseate Terns Sterna dougallii predict fledging success, first‐year survival and age at first return to the natal colony

Both intrinsic and extrinsic factors recorded at individual nests can predict offspring fitness and survival but few studies have examined these effects in the tropics. We recorded nestling survival, post‐fledging survival and age at first return of Roseate Terns breeding at Aride Island, Seychelles, over a 12‐year period (1998–2009). Nest data recorded at the egg, nestling and fledging stages were collected during six breeding seasons (1998, 2001–2005) and a capture‐mark‐recapture dataset of six cohorts of fledglings was obtained from 2001–2009. Logistic regression models were used to assess the predictive effect of reproductive variables on fledging success, while multistate capture‐mark‐recapture models were used to estimate post‐fledging survival and return–recruitment probabilities to the natal site. Nestling survival probability increased with earliness of laying and was negatively affected by tick infestation during the growth period (0–23 days). Fledging probability was also positively related to chick body condition, whereas other pre‐fledging reproductive parameters such as clutch size and egg size were not influential. A multistate modelling of age‐specific survival and return–recruitment (transition) rates found that first‐year survival differed between cohorts and was also negatively affected by tick infestation. Annual survival stabilized from age 2 onwards at 0.83 ± 0.02. Transition rates were positively related to body condition at fledging, with heavier individuals returning for the first time to the natal colony at a younger age compared with lighter individuals. These results highlight the importance of local conditions encountered by tropical seabirds during the breeding season in shaping demographic parameters.

Learned vocal group signatures in the polygynous bat Saccopteryx bilineata

Vocal group signatures facilitate group cohesion or the exclusion of nongroup members and thus greatly affect the social system of any given species. This is especially significant for highly mobile animals such as bats. The greater sac-winged bat, Saccopteryx bilineata, lives in a harem-based resource defence polygyny with patrilineal kin groups and female-biased natal dispersal. Pups of both sexes produce isolation calls to elicit maternal care. We analysed isolation calls from 25 pups born in seven different social groups in search of vocal signatures. In addition to a constant individual signature, isolation calls exhibited a group signature that became more prominent during ontogeny. Call convergence of fellow pups was independent of relatedness among pups and not driven by maturation effects, showing that the group signature was acquired through social modification, a form of vocal production learning. Behavioural observations of free-living bats indicated that isolation calls were used by adult males to appease more dominant males and to court unfamiliar females. The learned group signature in isolation calls may function as a ‘password’ that reliably associates individuals with their natal colony. This, in turn, could facilitate male harem acquisition and female inbreeding avoidance in the polygynous S. bilineata. The flexibility inherent in the vocal-learning process guarantees that crucial information can be promoted even under shifting social circumstances.

The professionalisation efforts of accountants in the Orange Free State, 1907–1927: An exploration of their first twenty years

Professionalisation forms an important domain in the accounting history arena. The geographical spread of professional organisations occurred via the relay of empire and the movement of international capital. Outcomes of professionalisation endeavours are strongly connected to the social and political context in which they occur. The mineral discoveries towards the end of the 19th century established South Africa’s first industrial community. As the country’s economy expanded, the virtues of simple living and conduct of business passed and there was a growing need for the services of individuals who had knowledge of accounting and of commerce. Most of the skilled accountants who migrated were of British descent. These accountants contributed to the development of the profession in South Africa. The Transvaal, Cape Colony, Natal and Orange River Colony (ORC) each established accounting societies around this time in response to the new industries and business. The Society of Accountants in the Orange River Colony was established in November 1907, five years after the conclusion of the South African War, by seven English gentlemen practising as accountants in Bloemfontein. This was the smallest society in comparison to the other colonies in Southern Africa at the time, and had grown from merely 16 foundation members in 1907 to 60 in 1927 with the passing of the Chartered Accountants Designation Act. The Society of Accountants and Auditors in the Orange River Colony (SAAORC) was a voluntary body, unlike the Transvaal and Natal societies. Accountants in the ORC could conduct their business as accountants and auditors and advertise themselves as such, whether they were members of the SAAORC or not. This article investigates the formation years of the accountants’ society in the Free State and explains the difference between this development path and that of the earlier preceding societies. The article explains the establishment of a British profession in a former Boer Republic and the mechanisms of professional closure implemented to safeguard the status of the profession.

Dispatches

Dispatches

Population Dynamics of Hawaiian Seabird Colonies Vulnerable to Sea‐Level Rise

Globally, seabirds are vulnerable to anthropogenic threats both at sea and on land. Seabirds typically nest colonially and show strong fidelity to natal colonies, and such colonies on low-lying islands may be threatened by sea-level rise. We used French Frigate Shoals, the largest atoll in the Hawaiian Archipelago, as a case study to explore the population dynamics of seabird colonies and the potential effects sea-level rise may have on these rookeries. We compiled historic observations, a 30-year time series of seabird population abundance, lidar-derived elevations, and aerial imagery of all the islands of French Frigate Shoals. To estimate the population dynamics of 8 species of breeding seabirds on Tern Island from 1980 to 2009, we used a Gompertz model with a Bayesian approach to infer population growth rates, density dependence, process variation, and observation error. All species increased in abundance, in a pattern that provided evidence of density dependence. Great Frigatebirds (Fregata minor), Masked Boobies (Sula dactylatra), Red-tailed Tropicbirds (Phaethon rubricauda), Spectacled Terns (Onychoprion lunatus), and White Terns (Gygis alba) are likely at carrying capacity. Density dependence may exacerbate the effects of sea-level rise on seabirds because populations near carrying capacity on an island will be more negatively affected than populations with room for growth. We projected 12% of French Frigate Shoals will be inundated if sea level rises 1 m and 28% if sea level rises 2 m. Spectacled Terns and shrub-nesting species are especially vulnerable to sea-level rise, but seawalls and habitat restoration may mitigate the effects of sea-level rise. Losses of seabird nesting habitat may be substantial in the Hawaiian Islands by 2100 if sea levels rise 2 m. Restoration of higher-elevation seabird colonies represent a more enduring conservation solution for Pacific seabirds.

To leave or not to leave: survival trade‐offs between different migratory strategies in the greater flamingo

1. The balance between costs and benefits of migration under different environmental, density-dependent and individual conditions may promote a broad range of migratory behaviours. We studied the factors influencing first-year migration and subsequent fidelity or dispersal among wintering areas, and the survival costs of different wintering behaviours in the greater flamingo (Phoenicopterus roseus). 2. We analysed by multievent capture-recapture modelling among-site dispersal/fidelity and site-dependent survival probabilities from 22 671 flamingos ringed in the Camargue (France) between 1977 and 2010 and resighted subsequently in their wintering grounds classified as France, Iberian Peninsula, Italy and North Africa. 3. We found that first- and second-year birds either resident or wintering at medium distances from their birth place, survived better than those wintering further afield. However, under severe winter conditions (extremely cold winter 1984-1985), individuals with the sedentary strategy suffered the highest levels of mortality. From the third winter onwards, the pattern of survival reversed: the long-distance wintering individuals (i.e. North Africa) survived better. 4. The proportion of first-year birds migrating for wintering was highly variable among cohorts and increased with favourable environmental conditions (wet years). After the first winter, birds showed high fidelity (>90%) to their previous wintering area and wintered preferably near their natal colony when they became adults (>2 years). 5. Survival estimates suggest that long-distance migration was costly for young and inexperienced individuals. Nonetheless, for adults, the most southern wintering areas seem to offer the most favourable local conditions for overwinter survival. 6. The higher availability of intermediate stopover sites during wet years may facilitate first-year migration. Then, once they have some wintering experience, flamingos appear to favour the known wintering grounds. As they grow older, dispersing towards the vicinity of the natal colony may provide higher breeding prospects for individuals wintering closer to this high-quality and saturated breeding ground, as predicted by the arrival-time hypothesis.

Colony pollen reserves affect body size, sperm production and sexual development in males of the stingless bee Melipona beecheii

The production of male sexual offspring by social insect colonies is often strongly seasonal or resource-dependent. In stingless bees, males are produced in smaller numbers under conditions of low colony food reserves; whether such males are negatively affected in traits related to reproductive success is not known. We compared body size, sperm production and sexual maturity in Melipona beecheii males reared with experimentally supplemented or reduced pollen reserves, but with otherwise equal numbers of workers and equal quantities of honey reserves. We also studied the same traits in males collected from non-manipulated colonies with pollen reserves intermediate between the supplemented or reduced groups but with more workers and honey reserves. Males reared under experimentally reduced pollen reserves had significantly smaller bodies and lower sperm counts compared to those reared in colonies with experimentally supplemented pollen reserves. There was also a significantly positive relationship between the number of sperm and body size in males across all colony treatments. The maximum number of sperm in seminal vesicles was recorded 2 days later in males from colonies with reduced pollen compared to males from colonies with supplementary pollen. Males from non-manipulated colonies were intermediate in size, sperm count and speed of maturation. Our study documents for the first time the existence of large size variation in males of stingless bees that is related with the amount of pollen reserves in their natal colony. We conclude that a colony’s pollen reserves have a major impact on male body size, sperm production and speed of sexual maturity in this stingless bee, which may be the case in other social insects. Stingless bees are a good model system to study the balance between colony-level selection and individual-level selection on male sexually selected traits such as body size.

No island hopping for Hawaiian petrels

Understanding the mechanisms of population differentiation is critical to studying evolutionary ecology, speciation and population connectivity. Gene flow via dispersal ultimately determines the levels and patterns of population differentiation for any species. Seabirds present an enigma with respect to dispersal potential and realized gene flow. They are capable of traveling tens of thousands of kilometers either on single foraging trips or during the non-breeding season, yet they are highly philopatric often returning not only to their natal island, but to their natal colony to breed. Their longevity (some live >50 years) and delayed sexual reproduction make using traditional mark-recapture methods to study dispersal more challenging. Molecular markers allow researchers to study multigenerational movements by measuring gene flow. Most of the population genetic studies on seabirds have found evidence of gene flow among breeding sites at small geographic scales (Friesen et al., 2007a). In order for populations to become, and remain, genetically homogenous, only a few individuals per generation need to be exchanged between breeding sites. Some seabirds do show evidence of restricted gene flow, however, these are often geographically clustered (for example, New Zealand seabirds), species with restricted dispersal (for example, flightless cormorant) or species with temporally segregated breeding (for example, band-rumped storm petrel) (Friesen et al., 2007a and references therein; Duffie et al., 2009; Friesen et al., 2007b).

Small-scale spatial variation in evolvability for life-history traits in the storm petrel

The evolutionary potential in the timing of recruitment and reproduction may be crucial for the ability of populations to buffer against environmental changes, allowing them to avoid unfavourable breeding conditions. The evolution of a trait in a local population is determined by its heritability and selection. In the present study, we performed pedigree-based quantitative genetic analyses for two life-history traits (recruiting age and laying date) using population data of the storm petrel over an 18-year period in two adjacent breeding colonies (only 150 m apart) that share the same environmental conditions. In both traits, natal colony effect was the main source of the phenotypic variation among individuals, and cohort variance for recruitment age and additive genetic variance for laying date were natal colony-specific. We found significant heritability only in laying date and, more specifically, only in birds born in one of the colonies. The difference in genetic variance between the colonies was statistically significant. Interestingly, selection on earlier breeding birds was detected only in the colony in which heritable variation in laying date was found. Therefore, local evolvability for a life-history trait may vary within a unexpectedly small spatial scale, through the diversifying natural selection and insulating gene flow. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 439–446. ADDITIONAL KEYWORDS: adaptability – animal model – evolution – heritability – laying date – recruiting age – selection.

Prey Abundance, Intraguild Predators, Ants and the Optimal Egg-laying Strategy of a Furtive Predator

Larval performance can have a great influence on female oviposition choice, especially in insects where the newly hatched offspring are unable to move any great distance to find an appropriate food source. For furtive predators, like the predatory midge Aphidoletes aphidimyza which preys on aphids while simultaneously residing and remaining undetected within their colonies, oviposition behaviour is crucial because these slow moving offspring are restrained to their natal colony. Here we develop a new model for predicting the optimum number of eggs that a furtive predator should lay in an aphid colony, based on: (1) the number of available prey (aphids); (2) the protection from predation conferred by “hiding” in the colony and (3) the effects of interspecific and intraspecific competition. We also explore the effect of aphid attendance by ants on oviposition behavior. We compare model predictions with empirical field observations of the clutch sizes of A. aphidimyza in apple orchards. The simplest of the four models best fits the observed data and provides the first field evidence that a furtive predator adjusts its clutch size as a function of prey density. The slope of the relationship between clutch size and aphid number is quite close to that predicted by our models suggesting that intra-clutch competition is the main factor governing furtive aphid midge oviposition choice.

BAMBATHA AT MPANZA: THE MAKING OF A REBEL

Bambatha is widely known as the chief who led a group of men to confront the Natal colonial government in protest against poll tax. He lived in a broken, sandy and stoney area known as Mpanza valley, to the north of Greytown, in the Natal colony of the former British Empire. The inhabitants of this valley were the Zulu tribe called Amazondi (officially called Abasengome). This land was dry and poor for cultivation and for game. It was a farmland owned by white men but settled by the Amazondi since 1854 as a “private location” of indigenous people who did not live in an officially designated Native Location (an exclusive site for the settlement of indigenous people). The white people were called the thorns. Bambatha led the last armed resistance of the Africans before the establishment of the Union of South Africa in 1910. He was eventually captured and beheaded. He provided the source of strength to boost the morale of those who continued with the struggle for liberation in subsequent years. This is the perception around Bambatha and his rebellion in 1906. But how exactly did it happen that he became a defiant chief who did not acquiesce to the demands of the colonial government? This book provides a descriptive analysis of the career of Bambatha until his flight to Zululand after the failure of his endeavour-armed resistance.

Kinship, parentage, and temporal stability in nursery colonies of Leisler’s bat (Nyctalus leisleri)

Levels of genetic relatedness within bat colonies are often unknown, and consequently the reasons for group formation and social organization are unclear. The Leisler’s bat (Nyctalus leisleri), like most temperate bat species, forms nursery colonies in summer. We used microsatellite markers to examine identity and to attempt to estimate relatedness among females within a nursery colony, over 2 consecutive years, to ascertain whether females show kinship and natal philopatry, testing the hypothesis that this is the basis of colony formation. Parentage and relatedness of young born within a colony was assessed to investigate mating patterns via male reproductive skew and whether males achieve mating success within their natal colony. While there was evidence for female philopatry, levels of genetic relatedness within colonies were low. This suggests that kinship is not a major determinant in group formation, as roosts also comprise a large number of distant relatives or non-kin. Roost switching and gene flow are likely to be high. Both sexes reproduced in their first year, whereas males appear to be the more dispersive sex. We argue that the physical environment as well as information sharing provided by communal roosting are likely to be important factors for the formation of these large natal colonies in N. leisleri and possibly other lineages of bats.

Black-footed ferret areas of activity during late summer and fall at Meeteetse, Wyoming

Radiotelemetry was used during 1983 and 1984 to collect information on short-term areas of activity for blackfooted ferrets (Mustela nigripes) near Meeteetse, Wyoming. This population ultimately provided ferrets for the captive-breeding program that bred and released offspring into the wild since 1991. We fitted 5 adult ferrets and 13 juveniles with radiotransmitters and followed their movements during late summer and fall. Adult males had 7-day areas of activity that were .6 times as large as those of adult females. Activity areas of adult males varied little in coverage or location on a weekly basis, but females sequentially shifted their areas. Unlike juvenile females, juvenile males tended to leave their natal colonies.

Recoveries of juvenile Giant Petrels in regions of ocean productivity: potential implications for population change

Explaining long-term population change for migratory seabirds such as Giant Petrels (Macronectes spp.) has proven elusive because only aspects of adult life-histories have been studied. There is a paucity of demographic data for juveniles however; there is a considerable amount of leg-band recovery location data for younger age-classes. Nestlings were leg-banded at two sub-Antarctic islands, and at two higher latitude Antarctic breeding colonies. Bands were most often recovered in winter within six months of liberation. Banded fledglings were recovered in known productive upwelling biomes. The birds had travelled between 350 and 6150 km downwind from their natal colonies to reach these biomes. The distances fledglings travelled to reach the biomes were correlated with the observed population trends at their natal colonies; negative/positive population trends were correlated with great/lesser distances travelled. This study highlights the potential importance juvenile life-history attributes when considering population change for long-lived seabird species, and identifies rich upwelling regions such as the Humboldt and Benguelen Currents that might be important foraging areas for this and other Procellariiform species with high conservation values.