Occurrence Of Breeding Research Articles

Wetland Selection by Breeding and Foraging Black Terns in the Prairie Pothole Region of the United States

Abstract. We examined wetland selection by the Black Tern (Chlidonias niger), a species that breeds primarily in the prairie pothole region, has experienced population declines, and is difficult to manage because of low site fidelity. To characterize its selection of wetlands in this region, we surveyed 589 wetlands throughout North and South Dakota. We documented breeding at 5% and foraging at 17% of wetlands. We created predictive habitat models with a machine-learning algorithm, Random Forests, to explore the relative role of local wetland characteristics and those of the surrounding landscape and to evaluate which characteristics were important to predicting breeding versus foraging. We also examined area-dependent wetland selection while addressing the passive sampling bias by replacing occurrence of terns in the models with an index of density. Local wetland variables were more important than landscape variables in predictions of occurrence of breeding and foraging. Wetland size was more important t...

Field Evidence for Colony Size and Aseasonality of Breeding and in Ansell's Mole-Rat,Fukomys anselli(Rodentia: Bathyergidae)

Ansell's mole-rat, Fukomys anselli, is a cooperatively breeding bathyergid endemic to the Lusaka Province of Zambia. During a 12-month field study involving the capture of 33 colonies of mole-rats, the number of occupants, breeding females and sex ratio within colonies were recorded. While thirty of these social groups contained a single breeding queen, three were found to exhibit plural breeding among females, having two queens present simultaneously. Mean ± S.E.M. colony size was 8.7 ± 2.2 (range 6–16, n = 33). The occurrence of plural breeding and small group size is consistent with the predictions of the aridity food distribution hypothesis for social species inhabiting mesic habitats. The sex ratio of the population was skewed towards females at 1.2:1. The mean mass of adult males was 63.0 ± 18.3 g (range 36.7–110.3, n = 87) while that for adult females was 52.9 ± 11.8 g (range 35.1–77.8, n = 86). Pregnant and lactating females were found throughout the study period from February 2009 to February 2010, indicating an aseasonal pattern of breeding in this species. Autopsy of individuals (n = 288) from the 33 colonies revealed a total of 19 pregnant females. Nine of these were in the latter stages of pregnancy and mean litter size was determined as 2.7 pups (range 1–4). Collectively, these new data reveal that Fukomys anselli share many similarities in life history and reproductive traits with the phylogentically closely related giant Zambian mole-rat, Fukomys mechowii.

Field evidence for colony size and aseasonality of breeding and in Ansell’s mole-rat, Fukomys anselli (Rodentia: Bathyergidae)

Ansell’s mole-rat, Fukomys anselli, is a cooperatively breeding bathyergid endemic to the Lusaka Province of Zambia. During a 12-month field study involving the capture of 33 colonies of mole-rats, the number of occupants, breeding females and sex ratio within colonies were recorded. While thirty of these social groups contained a single breeding queen, three were found to exhibit plural breeding among females, having two queens present simultaneously. Mean±S.E.M. colony size was 8.7±2.2 (range 6–16,n=33). The occurrence of plural breeding and small group size is consistent with the predictions of the aridity food distribution hypothesis for social species inhabiting mesic habitats. The sex ratio of the population was skewed towards females at 1.2:1. The mean mass of adult males was 63.0 ± 18.3 g (range 36.7–110.3, n=87) while that for adult females was 52.9±11.8 g (range 35.1–77.8, n=86). Pregnant and lactating females were found throughout the study period from February 2009 to February 2010, indicating an aseasonal pattern of breeding in this species. Autopsy of individuals (n=288) from the 33 colonies revealed a total of 19 pregnant females. Nine of these were in the latter stages of pregnancy and mean litter size was determined as 2.7 pups (range 1–4). Collectively, these new data reveal that Fukomys anselli share many similarities in life history and reproductive traits with the phylogentically closely related giant Zambian mole-rat, Fukomys mechowii.

Cooperative breeding by Buff-throated Partridge Tetraophasis szechenyii: a case in the Galliformes

Cooperative breeding is rarely found in the Galliformes. We report a case in Buff-throated Partridge Tetraophasis szechenyii, a sexually monochromatic Galliform species endemic to western China. A total of 68 groups were detected in the 2006–2009 breeding seasons, and cooperative breeding was observed to be facultative, with 64.7% (44/68) of pairs having up to three helpers of either sex (but predominantly male). Groups usually remained stable within the breeding season. Sampling revealed that all adult members exhibited behavioral efforts in terms of brooding, vigilance, and territorial display (including calling and fighting), with helpers especially focusing on territorial fighting. No evidence was found to suggest that the presence of helpers significantly enhanced a group’s breeding success and productivity compared to unaided pairs. Further studies, particularly intraspecific comparative analyses (for example, between populations or between sites) and those measuring the relatedness between helpers and other group members, are needed to understand the occurrence of cooperative breeding in this species.

Maternal weight, offspring competitive ability, and the evolution of communal breeding

Despite the widespread occurrence of communal breeding in animal societies, the fitness consequences for mothers are poorly understood. One factor that may have an important influence on the net benefits mothers gain from breeding communally is the competitive ability of their offspring, as mothers are likely to gain substantial advantages from producing young who can outcompete the offspring of other females for access to resources. Here, we investigate the factors that influence offspring competition in the communally breeding banded mongoose (Mungos mungo). We show that heavy offspring are more likely to win competitive interactions with their littermates. Heavy offspring also receive more care and are more likely to survive to independence in large communal litters where competition is most intense. Our results also indicate that offspring weight at emergence is positively correlated with the weight of the mother at conception. As a consequence, the offspring of heavy mothers are likely to enjoy marked competitive advantages during early life. Together, our findings strongly suggest that the competitive ability of offspring will influence the costs and benefits that females experience while breeding communally and highlights the need for closer examination of the factors that influence offspring competitive ability and the influence this may have on the evolution of communal breeding. Key words: aggression, cooperative breeding, joint nesting, maternal effects, plural breeding, reproductive skew. [Behav Ecol]

Large-scale climatic patterns forcing desert locust upsurges in West Africa

The desert locust represents a serious threat to food security in many African, Middle Eastern, and Southwest Asian countries. Desert locust breeding, maturation, and diffusion are strongly influenced by local environmental parameters, mainly rainfall, temperature, wind, and related features such as soil humidity and vegetation development. The recurring simultaneous occurrence of outbreaks and seasonal breeding over wide regions suggests the existence of large-scale forcing due to climatic anomalies. Even if the connections between climate anomalies and desert locust upsurges have been hypothesized in the literature, no inference has been demonstrated for large-scale climatic processes, allowing their potential use as predictors. In the present study we assessed a historical data series on desert locust population dynamics by integrating several data sources. A climatic analysis was carried out on a monthly basis covering the period 1979–2005 using the global NCEP-DOE Reanalysis dataset. The Wilcoxon non-parametric test was used to establish whether identified West African atmospheric patterns in upsurge years present significant differences compared to recession years. The analysis suggests a significant role of a weaker easterly flow at the core of the African Easterly Jet during spring, coupled with stronger westerly moisture advection. These climatic features may indeed explain meteorological conditions supporting many contemporaneous outbreaks, eventually developing into an upsurge (i.e. widespread rainfall events over key areas).

Low levels of extra-pair paternity in southern emu-wrens (Aves : Maluridae)

The frequency of extra-pair paternity (EPP) among birds varies considerably, with the highest rates (56–76%) reported in several species of fairy-wren (Maluridae). According to the ‘constrained female’ hypothesis, such high frequencies arise when females are emancipated from constraints on mate choice because they have access to alternative sources of parental care (cooperative breeding). We investigated the genetic mating system of a close relative of the fairy-wrens within the Maluridae, the southern emu-wren (Stipiturus malachurus). Southern emu-wrens share several life-history attributes with the fairy-wrens, but show relatively low levels of cooperation, providing an opportunity to assess how the frequency of cooperative breeding correlates with the frequency of EPP. We assessed paternity for 50 offspring within 27 emu-wren broods using species-specific microsatellite markers. Overall, only 12% of genotyped offspring resulted from extra-pair paternity, and 15% of broods contained at least one extra-pair offspring. We argue that opportunities for mate choice by female emu-wrens are restricted by their dependence on paternal care for offspring survival, as suggested by the constrained female hypothesis. The low occurrence of cooperative breeding in the southern emu-wren may thus help explain the extreme variation in the frequency of extra-pair paternity within this family.

Group size and composition are correlated with population density in the group‐territorial blue korhaan (Eupodotis caerulescens)

AbstractThe blue korhaan (Eupodotis caerulescens) is a poorly known bird endemic to the grasslands of southern Africa. It lives in permanently held territories defended by groups of individuals. During 2001 and 2002, 61 transects were carried out along 544 km of roads in Mpumalanga province (South Africa) to collect data on territory density and group size and composition in this species. Habitat, altitude and topography variables were measured to evaluate their influence on population density. Average territory density was 1.56 ± 0.19 (SE) territories per 5 km and maximum densities attained 5.6 territories per 5 km. Within its area of occurrence, higher densities occurred along transects with larger proportion of short grassland (either burned or grazed) and flatter topography. Mean group size was 3.03 ± 0.11 birds (n = 119), with 87.4% of the groups having one to four birds. Most common group composition was one male and one female‐like (34.5%), followed by two male and one female‐like (17.2%) and two male and two female‐like (13.8%). Single individuals were always males, and the male/female‐like ratio peaked at a group size of three and decreased thereafter. Mean group size increased with territory density (rs = 0.42, P = 0.007, n = 41). There were no differences in group size across habitat types. The occurrence of habitat saturation and cooperative breeding in this species could explain the observed results.

Fall Breeding of the Southern Leopard Frog (Rana sphenocephala) in Northeastern Arkansas

Abstract Our study appears to represent the western-most report of autumn breeding within this species' range, the first report of potential environmental cues stimulating the occurrence of fall breeding, and the first examination of egg clutches and spermatogenesis from fall breeding populations. We conducted calling surveys throughout the year over a 4 year period extending from 1999–2002 to determine the frequency of fall breeding in this species. Southern Leopard Frogs bred 20 September 2002 during heavy rains. Although we observed sporadic individual calling males in other years, lack of rain seemed to suppress breeding activities despite the presence of flooded agronomic fields and ditches in the region. We characterized 11 egg masses and the testicular condition of three males during years when fall breeding was observed. The number of eggs per mass in the fall was similar to that observed during the spring, but mass-per-egg was nearly twice that observed in studies of spring breeding frogs. The ha...

Help or disperse? Cooperation in termites influenced by food conditions

Ecological factors have been claimed paramount for the evolution and maintenance of cooperative group living in eusocial termites, as well as in cooperatively breeding birds and mammals. However, a clear demonstration of the role of any specific ecological factor in termites has been lacking. In the termite Cryptotermes secundus, individuals have two options, staying as helpers at the natal nest or developing into winged sexuals that disperse to found new colonies. An important ecological factor expected to influence the course of termite development is food availability; C. secundus nests inside a single piece of wood that serves as the sole source of food for the duration of the colony. As wood is consumed, the longevity of the colony is reduced, thus diminishing the potential fitness gains of staying at the nest. We experimentally investigated the occurrence of cooperative behavior and development under abundant- and limited-food conditions. Workers exposed to food-limited conditions were more likely to develop into dispersing sexuals and increased “selfishly” their food-acquisition behaviors. Proximately, a reduced frequency of proctodeal trophallaxis may have interfered with the distribution of pheromones that inhibit sexual development. Ultimately, decreased inclusive fitness benefits in food-limited, and thus short-lived nests, appear to explain the development of dispersing sexuals, supporting (1) the benefits-of-philopatry hypothesis as developed for the occurrence of cooperative breeding in vertebrates, and (2) predictions of reproductive skew theories.

Occurrence of acarid mites and breeding of Tyrophagus similis Volgin in rotten straws of rice

We let straws piled up and rot in the field, and investigated occurrence of acarid mites on them and fresh ones of rice. As a result, the number of acarid mites (Tyrophagus putrescentiae (Schrank)) reached its peak two months later, and decreased three months later on both straws. The number on the rotten straws was less than fresh straws. Then, we bred Tyrophagus similis Volgin by the rotten straws for 28 days at 24°C, 14L10D, starting with 20 mites. While the number of acarid mites on fresh straws amounted to about 1000 to 3700, it was 150 to 200 on rotten straws piled for three months. It may be possible to control their number by using rotten straws instead of fresh straws.

Occurrence and Evolution of Cooperative Breeding among the Diurnal Raptors (Accipitridae and Falconidae)

Occurrence and Evolution of Cooperative Breeding among the Diurnal Raptors (Accipitridae and Falconidae)

Occurrence and Evolution of Cooperative Breeding Among the Diurnal Raptors (Accipitridae and Falconidae)

Abstract Cooperative breeding, in which more than two individuals live in a group and raise offspring, usually in a single nest, is found in only 3% of avian species. On the basis of a review of the literature, we found reports of groups (usually trios) at nest sites in 42 species of diurnal raptors. At least one example of cooperative breeding was found in 29% of genera and 14% of species, distributed in both Accipitridae and Falconidae. Given the difficulty of obtaining behavioral observations necessary to detect cooperative breeding in most raptor species, combined with the large number of species that have been poorly studied, cooperative breeding in diurnal raptors may be more common than our data indicate. However, when data on the sex of the extra bird(s) or relationships among group members were available, patterns were quite varied. For 7 of 13 species, groups primarily contained multiple adult males, though three of those species also had groups formed from offspring that had delayed dispersal; three species had a low, but regular, occurrence of multiple females (females of groups laid eggs in the same nest); and the remaining three species were characterized by having extra birds that were yearlings or subadults. In over half of species, groups did not appear to be composed of related individuals, contrary to many cooperatively breeding passerine species where groups are primarily composed of offspring that have delayed dispersal. Our review suggests that the evolution of group living in many raptors may be independent of delayed dispersal, and that the factors important in explaining the evolution of that behavior depend upon the benefits of group living.

Age-Assortative Mating Related to Reproductive Success in Black-Crowned Night Herons

-Age-assortative mating occurs frequently in birds, and may be produced by active selection for older and more successful mates, but also simply by age-related differences in breeding time, or by mate fidelity, without age-related selection. We describe the occurrence of age-assortative breeding in the Black-crowned Night Heron (Nycticorax nycticorax) near Wuxi, China. Throughout the whole breeding season, 59% of the breeders were adults i.e., birds older than two years, and 41% were younger birds injuvenile plumage i.e., birds in their second year. Most of 206 pairs were strictly assorted by age, and only 2.4% had one adult and one juvenile. A part of this assortment was due to age-related differences in the breeding period, but even when this seasonality is accounted for, the observed frequency of mixed pairs is much lower than expected. Mate fidelity is not likely to account for the observed assortment. We conclude that the strict age assortment we observed in Black-crowned Night Herons is to be ascribed to active mate selection by age. Reproductive success was higher for pairs of adults than for those in juvenile plumage, while no difference was found for egg size, chick condition or asymmetry. Pairing between adults may therefore be adaptive because it enhances reproductive success. The high frequency of Black-crowned Night Herons breeding in juvenile plumage in China (41%) contrasts sharply with the situation in other parts of the species range, where birds injuvenile plumage rarely breed, are even seldom seen near colonies, and are believed to remain in their wintering areas. Received 2 February 2001, accepted 25 March 2001.

Breeding Biology of the White-fronted ChatEphthianura albifronsin a Saltmarsh near Melbourne

A colour-banded population of White-fronted Chats was studied to determine parental roles, the occurrence of multiple breeding, mate and site fidelity, the length of the breeding season, nest-site natural history and parameters of reproductive output. Apart from nocturnal incubation and brooding, which was performed by females, both sexes shared nesting duties equally and remained together throughout the breeding season. The breeding season was long (4.2 'equally good' months) and repeat nesting, up to at least five times, was common after successful and unsuccessful nests. Clutch size was small (2.75 eggs), reproductive success was low (18.5% of eggs laid) and most losses (83%) were due to predation. Nest predation may be an important factor in the evolution of the life histories of White-fronted Chats and other Australian bird species.

Behavioral Heterochrony and the Evolution of Birds' Helping at the Nest: An Unselected Consequences of Communal Breeding?

Helping behavior in communal or cooperative breeders is presumed by most researchers to have evolved as a direct result of natural selection. Hence, helping in different communal-species contexts is explained in terms of its adaptive or functional significance for the helper. The hypothesis that the expression of provisioning behavior by nonbreeding auxiliaries is an unselected consequence of the evolution of communal breeding is presented as an alternative to the functional hypotheses. First, I argue that the functional significance of nonbreeders' feeding offspring is irrelevant with respect to the evolutionary origin of the behavior because provisioning offspring is a constraint of many present-day species of birds, including those with helpers at the nest. I present a model that depicts provisioning by nonbreeding auxiliaries as an expression of a heterochronic change in ontogeny brought about as a result of a shift in life-history pattern (i.e., reduced breeding dispersal and parental tolerance). Because the cost to nonbreeding birds of exhibiting provisioning may be low relative to the benefits of (normal) parental provisioning, selection pressure on "helping" may be negligible. However, further evidence suggests that even if the costs were high, evolving the ability to discriminate between the contexts of the stimuli evoking the provision response would be difficult. Furthermore, even though the occurrence of communal breeding correlates almost perfectly with the occurrence of helping, estimates of inclusive fitness cannot be used to argue that there has been (separate) selection for provisioning by helpers. This problem arises because researchers have failed to distinguish between the causes and effects of natural selection. The "unselected hypothesis" is considered to have greater explanatory power than the various functional hypotheses because it provides a single explanation for provisioning by kin and non-kin in communal breeders and for the infrequent incidents of provisioning by individuals other than parents in non-communal species.

Plural Breeding in the Splendid Fairy‐wren, Malurus splendens (Aves: Maluridae), a Cooperative Breeder

AbstractGroups of the cooperatively breeding splendid fairy‐wren Malurus splendens may include more than one female. Previously this species has been described as singular breeding (only one female breeds). This paper describes the occurrence of plural breeding (PB) groups in 10% of group years, in which two females had separate nests. In all cases, the secondary female (Y) was related to the primary breeding female (X) and was generally a 2‐year old female which had helped in the group during the previous breeding season. Plural breeding was correlated with an increase in population density and in the number of female helpers; PB groups were larger than singular‐breeding groups. In most cases, the X female was occupied with her own nest or offspring when the Y female began to nest, and there was no aggression between them. Which birds helped the Y female to feed at her nest depended on the time between the hatching of the two nests. If the interval was small, some group members helped at each nest; with longer intervals, the group members began to feed at the earlier nest, and the other female was left to raise her brood alone. Female helpers were very active in feeding at single nestings, and the cost to an X female of a Y female breeding was mainly a loss of this assistance. The success of individual X nests was not affected. Effects on productivity were slight, but fewer X females in PB groups raised second broods than did experienced singular breeding females. Y females were less productive than X females, but no less productive than singular breeding novice females without helpers. It is not known whether Y females copulated with primary or secondary males within their group, or with males from outside the group. Certainly, they did not form an observable pairing with any male in the group. Plural breeding occurred in a minority of group years in response to extrinsic conditions and the current demographic situation, and shows the extreme plasticity of the mating system in M. splendens.

Synchronization of ovarian cycles within and between social groups in golden lion tamarins (Leontopithecus rosalia).

Synchronization of ovarian events has been reported in a number of primate species, with the temporal resolution of synchrony ranging from the occurrence of seasonal breeding within the annual cycle to a close matching of ovarian events within a single ovarian cycle. However, ovarian synchrony has not been reported in a New World primate. The temporal association of ovarian events was examined in female golden lion tamarins (Leontopithecus rosalia) living in the same or different social groups. Ovarian cyclicity was monitored by measuring the excretion of urinary estrogen metabolites. There was a high degree of synchronization in the occurrence of urinary estrogen peaks for females in different social groups (mean peak discrepancy = 2.1 days) and in females housed in the same social group (mean peak discrepancy = 1.3 days). Contrary to previous reports on callitrichid primates, daughters housed in their natal family group exhibited cyclic patterns of urinary estrogen excretion. These findings represent the first explicit demonstration of ovarian synchrony in a New World primate, and the tight coupling of ovarian cycles in female tamarins resembles the nature of menstrual synchrony in human females.

Evidence of itinerant breeding of the Red‐billed Quelea Quelea quelea in the Ethiopian Rift Valley

This paper provides evidence for itinerant breeding by Red‐billed Quelea Quelea quelea in the Ethiopian Rift Valley. Queleas were mass‐marked with aerially applied fluorescent particles in two separate nesting areas in southwestern Ethiopia during June 1981. Marked adults from both areas were recovered from nesting colonies in the Awash River Valley during August and September, up to 100 days post‐spray and between 500 and 700 km to the north of the spray sites. In the Awash colonies, the presence of marked adults in breeding plumage with interrupted primary wing‐moult, together with two age classes of juveniles, suggests that this was the second nesting. The progress of both the post‐breeding and post‐juvenal primary moults was consistent with an earlier breeding in May and June. The timing of the arrival and departure of birds from these nesting areas also supported the occurrence of double breeding by the same birds. Furthermore, the composition of black facial mask types of adult males was more similar between samples from the southern Ethiopian Rift and Awash Valley than between samples from either of these areas and samples from outside the Rift, providing additional evidence that the same population of birds bred in these two areas of the Rift Valley.Nesting colonies in both areas were scattered in time and space. Colonies in the Awash were distributed for more than 300 km and were established over a two‐month period, which coincided with local differences in the timing of the seeding in grasses. This wide distribution probably increases nesting success in such areas of locally variable rainfall. This contrasts with a stategy of mass migration, where concentrated breeding occurs where and when suitable conditions are first encountered.Knowledge of the location and timing of previously successful nesting areas may increase the success of itinerant breeding, as Queleas seem to use the same areas in successive years if conditions are favourable. Recoveries of marked birds in the Awash were segregated according to both spray site and sex, suggesting some degree of group cohesion by sex from the first to the second nesting. We speculate that post‐nesting group cohesion of adults may provide a means to maintain the integrity of collective group information on seasonal movements. Group cohesion may be facilitated by the high degree of nesting synchrony within colonies.

Weather and the Harvest of Cottontails in New Jersey

Correlations between harvest of cottontails (Sylvilagus floridanus) and weather variables during the breeding season were examined. The harvest variable was a standardized measure of the number of rabbits killed/hunter on selected public hunting areas of New Jersey on the opening day of small-game season. Weather variables included measures of rainfall and temperature during the previous breeding season. Multiple regression analysis indicated two rainfall variables significantly related to harvest: (1) the summation of March and September rainfall was highly significant (F1, 4-= 24.79; r' = 0.36) and probably reflected the importance to the fall harvest of first-litter survival coupled with survival of young produced by the breeding of first-litter survivors, and (2) April through August rainfall contributed to the model in an additive manner. The number of months during this period with 12.5 cm or more of rainfall was significantly related to harvest (F2,, 1 = 3.80) and accounted for an additional 4 percent of variability in opening-day harvest. J. WILDL. MANAGE. 40(4):658-662 The harvest of cottontail rabbits can vary a great deal from year to year (Wight 1959). This variability frequently is attributed to the effect of weather on breeding success during the previous season (Smith 1966:366), but a survey of the literature revealed no studies that have identified quantitative variables with predictive value. Meslow and Keith (1971) demonstrated a relationship between juvenile mortality and weather variables in snowshoe hares ( Lepus americanus), but such a relationship has not been demonstrated for cottontails. Life tables for cottontails (Lord 1963:79), however, indicate that 75 percent of rabbit mortality occurs within the first 4 months of life, suggesting that factors affecting juvenile survival would have a significant effect on the population and subsequent harvest of cottontails. The cottontail rabbit begins breeding in late February or early March, with the first litter generally born in March (Conaway and Wight 1962). Subsequent litters are produced at approximately monthly intervals throughout the summer, owing to a postpartum estrus and 28-day gestation period (Casteel 1967); the last litter usually is born in late August or early September (Lord 1963). The occurrence of juvenile breeding in the cottontail is well documented (Negus 1959, Lord 1963, Casteel and Edwards 1964), and the importance of juvenile breeding to the fall harvest has been postulated (Lord 1958, 1963). Kibbe and Kirkpatrick (1971) suggested that most juvenile breeding may involve only first-litter juveniles. The relative survival of this first litter thus has the potential of contributing exponentially to the fall rabbit population, whereas success of all other litters contributes only in an additive man-