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We describe the diet of Thamnophis melanogaster on the Mexican plateau, including geographic variation between populations in the Lerma and Tula drainages (represented by 39 localities), annual and seasonal variation in an isolated population in the Nazas drainage, and sexual and size-related variation in all three drainages. The Mexican Black-bellied Gartersnake inhabits banks of streams, rivers, canals, ponds, and lakes, where it captures fishes, leeches, crayfishes, tadpoles, earthworms, and frogs by foraging underwater. There was no geographic variation between the Lerma and Tula populations in proportions of prey taxa consumed, but whereas primary and secondary tadpole stages were consumed by snakes in Lerma, only secondary stages were consumed by snakes in Tula. Crayfishes, novel prey for this genus, were consumed over a restricted zone in the contiguous headwaters of the Lerma and Tula drainages. Interannual and seasonal variation in proportions of annelids and anurans ingested was documented in the Nazas population, and attributed to temporal change in relative abundance of prey taxa and snake size classes. Snake size was a major determinant of diet in all three drainages, affecting proportions of different prey taxa consumed and the upper limits on the mass of ingested prey. In the three drainages, sexes were similar in body size and consumed the same prey taxa in similar proportions and masses. We discuss proximate and functional determinants of diet and suggest that the observed interannual and seasonal variation observed in Mexican Black-bellied Snakes is due mostly to temporal variation in prey availability and proportions of snake size classes. [ABSTRACT FROM AUTHOR]

Experiments on birds, fish and mammals have shown that adverse conditions during infancy can produce diverse long-term and delayed deficits during adulthood, prejudicing both the individual and its offspring. Natural selection should prepare animals to cope with adversity of the type, magnitude and timing that commonly occur in their natural habitat, but very little is known about such evolved developmental buffering against natural 'poor starts' in life. In two-chick broods of the blue-footed booby Sula nebouxii, the junior (younger) chick usually experiences aggressive subordination, reduced nutrition and growth and elevated circulating corticosterone. To test whether this poor start produces long-term, delayed or intergenerational deficits in body size, body condition or cell-mediated immune response, we measured 3-8 yr old female breeders banded as chicks, and their infant offspring. Results failed to support our predictions. Compared to former seniors and former singletons (solitary nestlings), former juniors showed no deficit in cell-mediated immune response at any age. They showed an 8.04% deficit in body condition at age 4-6 yr but this deficit disappeared completely by age 7-8 yr. Furthermore, their offspring showed no deficits in body size, body condition or immune response. Junior chicks are affected by their poor start, but their developmental resilience, also confirmed by studies of post-fledging survivorship, recruitment, natal dispersal, aggressive nest defense and reproduction, is evidence of evolved developmental buffering against predictable adversity during infancy. [ABSTRACT FROM AUTHOR]

The behaviour that mediates divorce and partner change in socially monogamous species is largely unstudied and unknown, although roles and adaptive functions in some birds have been inferred from breeding outcomes, partial behavioural records and captive studies. Here, roles and functions of natural within-season mate switching of a colonial bird were characterized by describing interactions over many days during the whole daylight period. Switching occurred in 5.9% of bluefooted booby pairs and was initiated by desertion of males or, less commonly, females. Three male desertions were consistent with either the Errors of Mate Choice or Incompatibility hypotheses but were better explained by our new Unfaithful Mate hypothesis because infidelity of the mate preceded desertion. Another two male desertions were more consistent with the Better Options hypothesis because the males switched to their ongoing extra-pair (EP) partners. One female desertion was consistent with the Errors of Mate choice or Incompatibility hypotheses, and another with the Better Options hypothesis. All five deserted females switched promptly to their EP partners. Thus, most switches consisted of (1) males replacing a possibly unsatisfactory partner with a new (already identified or to be identified) partner, or (2) deserted females pairing with their EP partners. [ABSTRACT FROM AUTHOR]

A survey of the helminth fauna of the blue-footed booby, Sula nebouxii, on Isla Isabel, off the Pacific coast of Mexico, is presented. Eight parasite species were found: 4 digeneans (Galactosomum puffini, Mesostephanus microbursa, Opisthometra planicollis, and Renicola thapari), 3 nematodes (Contracaecum sp., Porrocaecum sp., and Tetrameres sp.), and 1 cestode {Tetrabothrius sp). All these species are reported for the first time in the blue-footed booby, and they represent 8 new locality records as well. Species accumulation curves suggest these 8 parasite species comprise the total helminth fauna of this population of boobies. The most frequent and abundant parasite was R. thapari, inhabiting the kidney of its host. In male boobies, a significant negative correlation was found between abundance of R. thapari and host body condition. [ABSTRACT FROM AUTHOR]

There is increasing interest in the impacts of El Niño Southern Oscillation (ENSO) on reproduction of apical predators such as seabirds and marine mammals. Long-term studies documenting ENSO effects on reproduction of seabirds in the warm tropics are scarce, and differential sensitivity of breeding parameters to ENSO has rarely been explored. Analysis of 18 years of breeding data from a colony of the blue-footed booby Sula nebouxii (Milne-Edwards) showed a delay in onset of breeding when the global Southern Oscillation Index was negative; each unit of the atmospheric pressure differential (hPa) across the Pacific Ocean meant a delay of 7 days. ENSO conditions also produced declines in breeding participation, clutch size, brood size, hatching success and fledging success, especially when surface waters surrounding the colony were warmer during winter and spring. Each additional degree (°C) of water temperature produced a reduction of 0·45 fledglings per nest. Different breeding parameters were sensitive to ENSO indices in different blocks of months. Warming of local waters during the winter was associated with decline in ocean productivity in the current year and the following year, consistent with ENSO impacts on breeding parameters being mediated by effects on local productivity and prey availability. However, there was no evidence of lagged effects of ENSO on any breeding parameter. Comparison of 5 years revealed that when local surface waters were warm, chicks grew more slowly, but no effects of ENSO on weight and size of eggs were evident in data of 9 and 7 years, respectively. Our findings extend evidence of impacts of ENSO on seabird reproduction to the eastern tropical Pacific and indicate that several breeding parameters of blue-footed boobies (but not egg size) are affected in the short term by ENSO conditions, particularly by local anomalies in sea surface temperature associated with decline in ocean productivity. [ABSTRACT FROM AUTHOR]

Theories of ageing predict that early reproduction should be associated with accelerated reproductive senescence and reduced longevity. Here, the influence of age of first reproduction on reproductive senescence and lifespan, and consequences for lifetime reproductive success (LRS), were examined using longitudinal reproductive records of male and female blue-footed boobies ( Sula nebouxii) from two cohorts (1989 and 1991). The two sexes showed different relationships between age of first reproduction and rate of senescent decline: the earlier males recruited, the faster they experienced senescence in brood size and breeding success, whereas in females, recruiting age was unrelated to age-specific patterns of reproductive performance. Effects of recruiting age on lifespan, number of reproductive events and LRS were cohort- and/or sex-specific. Late-recruiting males of the 1989 cohort lived longer but performed as well over the lifetime as early recruits, suggesting the existence of a trade-off between early recruitment and long lifespan. In males of the 1991 cohort and females of both cohorts, recruiting age was apparently unrelated to lifespan, but early recruits reproduced more frequently and fledged more chicks over their lifetime than late recruits. Male boobies may be more likely than females to incur long-term costs of early reproduction, such as early reproductive senescence and diminished lifespan, because they probably invest more heavily than females. In the 1991 cohort, which faced the severe environmental challenge of an El Niño event in the first year of life, life-history trade-offs of males may have been masked by effects of individual quality. [ABSTRACT FROM AUTHOR]

In marine ecosystems climatic fluctuation and other physical variables greatly influence population dynamics, but differential effects of physical variables on the demographic parameters of the two sexes and different age classes are largely unexplored. We analyzed the effects of climate on the survival and recruitment of both sexes and several age classes of a long-lived tropical seabird, the Blue-footed Booby (Sula nebouxii), using long-term observations on marked individuals. Results demonstrated a complex interaction between yearly fluctuations in climate (both local and global indexes, during both winter and breeding season) and the sex and age of individuals. Youngest birds' survival and. recruitment were commonly affected by local climate, whereas oldest birds' parameters tended to be constant and less influenced by environmental variables. These results confirm the theoretical prediction that sex- and age-related variation in life-history demographic traits is greater under poor environmental conditions, and they highlight the importance of including variability in fitness components in demographic and evolutionary models. Males and females showed similar variation in survival but different recruitment patterns, in relation to both age and the spatial scale of climatic influence (local or global). Results indicate different life-history tactics for each sex and different ages, with birds likely trying to maximize their fitness by responding to the environmental contingencies of each year. [ABSTRACT FROM AUTHOR]

Senescence could depress prenatal and postnatal capacities of mothers to invest in offspring. Longitudinal observations on the blue-footed booby (Sula nebouxii) revealed a quadratic effect of female age on fledgling production and cohort differences in rate of reproductive decline. By swapping clutches between females of different ages, we tested whether reproductive senescence is due to decline in egg quality or capacity to care. As laying mothers aged, egg size, ulna length of 5-day-old chicks, and ulna growth of second chicks up to age 30 days declined, and as rearing mothers aged, ulna growth and cellular mediated immune response of second chicks diminished. Oddly, senescent females (>11 years) produced more fledglings when rearing offspring of middle-aged females (8-11 years) than when rearing offspring of senescent or young females. Thus, senescence reduced egg quality and rearing capacities, and reproductive success of senescent mothers depended on prenatal effects associated with the age of the laying mother. Reproductive senescence of boobies may involve constraints on resources allocated to reproduction as well as adaptive adjustment of provision and care according to offspring value, implying that negative effects of senescence on offspring survival can be ameliorated by plasticity in postlaying or postnatal care. [ABSTRACT FROM AUTHOR]

In multitudinous breeding colonies, kin interactions could go unnoticed because we are unaware of the kinship among adults we observe. Evidence of cooperation and competition between close adult kin in a blue-footed booby colony was sought by analyzing patterns of natal dispersal and proximity of nests. Male and female recruits nested closer to their own natal sites than to their parents’ current sites. Males (only) dispersed less far when both parents were present than when no parent or one parent was present, but not selectively close to fathers versus mothers when these were divorced. Neither parental presence nor parental proximity affected breeding success of recruits of either sex. Although distances between the nests of simultaneously recruiting broodmates were unrelated to their sex, males dispersed 13.1 m less when a sister was present than when a brother was present. Neither sex was affected in its dispersal distance by the presence or hatching order/dominance of a broodmate. Neither sex was affected in its breeding success by the presence versus absence of a broodmate, although female success increased with proximity of their brothers. Parents and sisters may actively or passively help males establish their first territories near their natal sites and nearby brothers may help females in their first breeding attempts; otherwise, boobies do not influence each other’s natal dispersal and first breeding success. It appears that boobies do not nest selectively close to or far from their parents, offspring, or broodmates. Why there is apparently so little cooperation and altruism between close adult relatives in booby colonies is puzzling. [ABSTRACT FROM AUTHOR]

Contradictory patterns of density-dependent animal dispersal can potentially be reconciled by integrating the conspecific attraction hypothesis with the traditional competition hypothesis. We propose a hypothesis that predicts a U-shaped relationship between density and both natal and breeding dispersal distance. Using 10 years of observations on a breeding colony of the Blue-footed Booby (Sula nebouxii), the hypothesis was confirmed by documenting simultaneous positive and negative density-dependent dispersal distances in natal and breeding dispersal of males and breeding dispersal of females within the colony. Point-pattern analyses demonstrated that the breeding sites of Blue-looted Boobies were highly aggregated in all years within a large study area. and aggregation presumably resulted in heterogeneity in patch density throughout the colony. As predicted, at moderate to high densities, dispersal distances showed positive density dependence, with individuals moving to lower density patches. In contrast, at low to moderate densities, dispersal distances showed negative density dependence, with individuals moving to higher density patches. In both sexes of the 1994 cohort, the higher the mean density in patches used by an individual over the long term (up to age I 1 years), the fewer fledglings it produced. A positive effect of density on long- term reproductive success was not detected, possibly because birds that failed during pair formation or incubation were not sampled. Density of conspecifics may be an important influence on habitat selection of breeders, and dispersal may tend to carry individuals to patches where pair formation opportunities are better and negative effects of competition on reproductive success are reduced. [ABSTRACT FROM AUTHOR]

In some vertebrate species, parents create a large brood or litter then, in the event of unfavourable ecological conditions, apparently allow the number of offspring to be adaptively reduced through siblicide. But how is sibling aggression regulated so that deaths occur only in unfavourable conditions? One proposed mechanism is brood size-dependent aggression. Two experiments tested for this mechanism by reducing three-chick broods of blue-footed boobies either during or after the period of dominance hierarchy establishment. In neither experiment did aggression of the two eldest and highest ranking chicks decline after removal of the youngest broodmate, in comparison with controls. These results suggest that dominant booby chicks do not become less aggressive to each other after disappearance of their youngest broodmate and that this species does not show brood size dependent aggression. Elder blue-footed booby chicks increase their attacks on broodmates when they receive less food, and this mechanism may be sufficient to tailor brood size to food availability. [ABSTRACT FROM AUTHOR]

The titles reviewed in this section of Ibis are available for reference at the Alexander Library of the Edward Grey Institute of Field Ornithology, Department of Zoology, South Parks Road, Oxford, UK. The library is open to Ibis readers, Monday to Friday (09:00–17:00 h). Please write, telephone (+44 (0)1 865 271143) or email ( or ) prior to your visit to ensure the library is open. The aim of the Alexander Library is to build up a comprehensive collection of literature as a service to ornithologists. Its holdings include an extensive range of periodicals and a large number of reprints drawn from many sources: additional reprints of readers’ papers are always welcome. The library has always greatly benefited from its close relationship with the BOU. For many years, all journals received in exchange for Ibis have been deposited in the library, as have most of the books sent for review, through the generosity of reviewers and publishers. In return, as a service to readers, this review section of Ibis is organized and edited by Michael G. Wilson and Professor Ben Sheldon of the Edward Grey Institute, with the help of a panel of contributors. They are always grateful for offers of further assistance with reviewing, especially with foreign-language titles. Books for review: publishers are kindly asked to send two copies of each title to Ibis Book Reviews, Alexander Library, EGI, Dept of Zoology, Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK. This book review section is supported by Subbuteo Natural History Books. Subbuteo are an international mail-order book company stocking over 2000 titles covering all natural and environmental sciences. They can also source titles from around the world. Titles reviewed in Ibis can be ordered from Subbuteo and payment can be made by credit card or cheques in £/$. Postage, packing and insurance is £1.99 per order. International postage is charged at cost; please contact Subbuteo for a quote. Subbuteo Natural History Books Ref. 0252, The Rea, Upton Magna, Shrewsbury SY4 4UR, UK. Tel: +44 (0)870 010 9700 Fax: +44 (0)870 010 9699 Email: Website: [ABSTRACT FROM AUTHOR]

We examined androgens in clutches of two booby species that differ in their sibling conflict. Blue-footed booby Sula nebouxii chicks show an aggression-submission relationship, aggression is normally moderate and siblicide is facultative. Brown booby Sula leucogaster chicks show an aggression-aggression relationship, aggression of both chicks can be relentless and siblicide is obligate. The parental favoritism hypothesis predicts that egg mass, yolk mass and yolk androgens should decline with laying order less in the blue-footed booby than in the brown booby, to promote the survival of the former's junior chick. The eggs of the blue-footed booby had higher yolk concentrations of 5α-dihydrotestosterone (DHT) and lower concentrations of testosterone (T); both species had similarly high yolk concentrations of androstenedione (A). Intra-clutch variation in yolk DHT, T and A failed to support our predictions. In both species, first and second eggs showed similar concentrations of all three hormones and were of similar size, although in the blue-footed booby (only) yolk masses declined with laying order. Brown booby mothers make junior chicks vulnerable to siblicide by hatching them 5 d after their broodmates, but not by differential allocation of egg androgens or nutrients. Blue-footed booby mothers appear to prepare junior chicks for thriving in a subordinate non-provocative role by hatching them 4 d after their broodmates and providing them with 10% less yolk. To orchestrate agonism within the brood, these boobies may rely more on hatch intervals and yolk provision than on androgens. [ABSTRACT FROM AUTHOR]

In many parentally fed species, siblings compete for food not only by begging and scrambling, but also by violently attacking each other. This aggressive competition has mostly been studied in birds, where it is often combined with dominance subordination, aggressive intimidation, and siblicide+ Previous experimental and theoretical studies proposed several life-history, morphological, and behavioral variables that may facilitate the evolution of broodmate aggression, and explain its taxonomic distribution. Here we apply phylogenetic comparative analyses for the first time to test the influence of five hypothesized facilitators of the evolution of broodmate aggression, analyzing 69 species in seven avian families using two quantitative measures of aggression: incidence and intensity. We show that incidence and intensity of aggression increase with long nestling periods and indirect feeding, and small brood size is associated with intense aggression. Large food parcels were not correlated with either the incidence or intensity of aggression. Our study suggests that indirect feeding, long nestling periods, and small broods, possibly in combination with other factors, have tended to favor the evolution of aggressive broodmate competition. [ABSTRACT FROM AUTHOR]

1. Understanding the effects of individual and population factors on variation in breeding dispersal (the movement of individuals between successive breeding sites) is key to identifying the strategies behind breeders’ movements. Dispersal is often influenced by multiple factors and these can be confounded with each other. We used 13 years of data on the locations, mates, breeding success and ages of individuals to tease apart the factors influencing breeding dispersal in a colonially breeding long-lived seabird, the blue-footed booby Sula nebouxii. 2. Breeding dispersal varied among and within years. Males dispersed further in years of higher population density, and late breeding males and females dispersed further than early breeders. This temporal variation related to changes in competition for territory was taken into account in all tests of individual factors influencing breeding dispersal. 3. Individuals that retained their mates from the previous year dispersed shorter distances than those that changed their mates. 4. The effect of previous breeding success depended on mate fidelity. Unsuccessful breeding induced greater dispersal in birds that changed their mates but not in birds that retained their mates, indicating that breeders who change mates may take their own previous breeding experience into account during habitat selection. Faithful individuals may have to stay close to their previous sites to encounter their mates. 5. Male divorcees dispersed over shorter distances than their former mates, possibly because males contribute more than females to establishing territories. 6. Dispersal of males and females declined with increasing age over the first 10–11 years of life, then increased in old age, possibly due to senescent decay in the ability to compete for mates and territories. [ABSTRACT FROM AUTHOR]

To determine whether solicitation by blue-footed booby chicks accurately encodes their need for food, we independently manipulated the body condition and recent food ingestion of singleton chicks and recorded three measures of begging. Variations in the three measures of begging covaried only partially, but in general, chicks begged more intensely when they were in poor body condition and also when suffering recent food deprivation. Effects of body condition and recent food deprivation on begging were broadly additive, although deprived chicks in poor condition failed to beg more intensely than those in good condition. Protracted short-term deprivation may create such a high level of need that the body condition component of need becomes temporarily unimportant. Parents more frequently fed chicks that begged more intensely, chicks in poor condition, and chicks suffering food deprivation. Deprived chicks in poor condition received more food than deprived chicks in normal condition even though they did not beg more intensely, possibly because parents responded not only to current begging but also to begging earlier in the day, or to other cues to body condition. These results support the hypothesis that begging of boobies represents honest signaling of need. [ABSTRACT FROM AUTHOR]

The Feeding Method hypothesis (FMH) proposes that the way parents transfer food to chicks influences whether broodmates compete for it aggressively or non-aggressively. The FMH assumes that aggression is more efficient for securing a large share of food when prey items pass from bill to bill (direct feeds) than when prey is deposited on the nest floor (indirect feeds). In species with a developmental transition from indirect to direct feeding, the hypothesis predicts more aggression during direct than indirect feeds and an increase in rates of aggression as feeding becomes increasingly direct. We quantified development of aggression and feeding in two-chick cattle egret (Bubulcus ibis) broods in order to test the FMH's assumption and its two developmental predictions. We also examined whether changes in rates of aggression early in the nestling period are better predicted by the Feeding Method, Food Amount or Early Dominance Establishment hypotheses. Neither the assumption nor either of the predictions of the FMH was supported and, if anything, senior broodmates were more aggressive early in the nestling period when feeding was indirect. These observations cast doubt on the ultimate influence of feeding method on use of aggression and, especially, on the role of direct feeding as a proximate trigger for aggression. Rates of aggression better fitted the temporal patterns predicted by Early Dominance Establishment and Food Amount hypotheses. [ABSTRACT FROM AUTHOR]

According to the desperado sibling hypothesis, chicks of obligately siblicidal species kill their junior broodmates as early as possible because junior broodmates face dire ecological prospects and are consequently predisposed to aggressively overthrow elder broodmates by all-out aggression. The agonistic behavior of junior chicks is virtually unknown because they die so young. We investigated the agonistic behavior of hypothetical desperados by fostering junior brown boobies (Sula leucogaster, an obligately siblicidal species) into nests of the blue-footed booby (S. nebouxii, a facultatively siblicidal species) containing an older singleton blue-foot chick. Controls were junior blue-footed boobies fostered into the same situation. Junior brown boobies were 7 times more aggressive than controls and most of them dominated their elder and larger nestmates. Four of nine brown booby juniors showed relentless aggression, delivering up to 711 pecks, bites and pushes (including "expulsion pushes") per hour, thereby overwhelming nestmates 90% heavier and permanently expelling one of them from the nest. Similarly, in natural broods of two surviving brown booby chicks, the losing chick was 13 times as aggressive as blue-foot subordinates, up to at least age 7 weeks. Contrast of the two species of booby suggests the evolution of agonistic roles within broods may be partly driven by selection on potential victims to express a level and type of aggressiveness appropriate to their status-related ecological prospects. [ABSTRACT FROM AUTHOR]

The dual concern model suggests that pairs of animals can use four different behavioural strategies to resolve disputes that arise when making joint decisions. Based on their reproductive biology, we predicted that mated pairs of blue footed boobies would use one of these strategies, collaboration, when deciding on a location for their nest. Many of the behaviour tactics diagnostic of collaboration were observed in boobies. For instance, nestsite selection was accompanied by extensive exchanges of a specialized communication signal (nestpointing), rates of nestpointing at a given site were strongly related to the likelihood that a pair would select that site for their nest, couples in which the male and female 'disagreed' about the merits of an initial site went on to investigate additional sites together ('expanding the pie'), individuals pointed at maximal rates at a site only after their partner had already pointed at that same site ('feeling out procedures'), and both sexes appeared to have 'veto power' over potential nestsites, in the sense that a site was virtually never accepted for the nest if one of the two partners failed to point at that site prior to clutch initiation. These results support the hypothesis that mated pairs of blue footed boobies may use collaborative tactics when selecting a nestsite; descriptive accounts suggest that similar tactics may occur in other birds in which mated pairs jointly decide on the location for their nest. [ABSTRACT FROM AUTHOR]

Focuses on the size dimorphism in avian blue-footed booby. Increase in mass and ulna rates in female offspring of the blue-footed bobby; Similarity in the parental feeding rates to fledgling sons and daughters; Significance of faster motor development in male species.

When the costs of rearing males and females differ progeny sex ratios are expected to be biased toward the less expensive sex. Blue-footed booby ( Sula nebouxii) females are larger and roughly 32% heavier than males, thus presumably more costly to rear. We recorded hatching and fledging sex ratios in 1989, and fledging sex ratios during the next 5 years. In 1989, the sample of 751 chicks showed male bias at hatching (56%) and at fledging (57% at ˜90 days). Fledging sex ratios during the five subsequent reproductive seasons were at unity (1 year) or male-biased, varying from 56% to 70%. Male bias was greater during years when mean sea surface temperature was warmer and food was presumably in short supply. During two warm-water years (only) fledging sex ratio varied with hatching date. Proportions of male fledglings increased with date from 0.48 to 0.73 in 1994, and from 0.33 to 0.79 in 1995. Similar results were obtained when the analysis was repeated using only broods with no nestling mortality, suggesting that the overall increase in the proportion of males over the season was the result of sex ratio adjustments at hatching. The male-biased sex ratio, and the increased male bias during poor breeding conditions supports the idea that daughters may be more costly than sons, and that their relative cost increases in poor conditions. [ABSTRACT FROM AUTHOR]

Weather conditions can profoundly affect avian reproduction. It is known that weather conditions prior to and after the onset of reproduction can affect the breeding success of birds. However, little is known about how seasonal weather variability can affect birds' breeding performance, particularly for species with a slow pace of life. Long-term studies are key to understanding how weather variability can affect a population's dynamics, especially when extreme weather events are expected to increase with climate change. Using a 32-year population study of the Blue-footed booby (Sula nebouxii) in Mexico, we show that seasonal variation in weather conditions, predominantly during the incubation stage, affects offspring survival and body condition at independence. During most of the incubation period, warm sea surface temperatures were correlated with low hatching success, while rainfall in the middle of the incubation stage was correlated with high fledging success. In addition, chicks from nests that experienced warm sea surface temperatures from the pre-laying stage to near-fledging had lower body condition at 70 days of age. Finally, we show that variable annual SST conditions before and during the incubation stage can impair breeding performance. Our results provide insight into how seasonal and interannual weather variation during key reproductive stages can affect hatching success, fledging success, and fledgling body condition in a long-lived neotropical seabird. [ABSTRACT FROM AUTHOR]

The article discusses research on the effect of age and reproductive effort of male blue-footed boobies to their sexual attractiveness. A long-term dataset revealed that the expression of foot colour, which reflects the sexual attractiveness of the male boobies, deteriorates as animals age and accumulate reproductive events. The authors report that their results support the idea that sexual attractiveness is limited by the allocation of resources to reproduction.

Assortative mating by telomere lengths has been observed in several bird species, and in some cases may increase fitness of individuals. Here we examined the relationship between telomere lengths of Blue-footed Booby (Sula nebouxii) mates, long-lived colonial seabirds with high annual divorce rates. We tested the hypothesis that interactions between maternal and paternal telomere lengths affect offspring and parental survival. We found that relative telomere lengths (RTL) were strongly positively correlated between members of a breeding pair. In addition, RTL of both parents interacted to predict fledgling recruitment, although fledglings with two very long-RTL parents performed only averagely. Telomere lengths also predicted adult survival: birds with long telomeres were more likely to survive, but birds whose mate had long telomeres were less likely to survive. Thus, having long telomeres benefits survival, while choosing a mate with long telomeres benefits reproductive output while penalizing survival. These patterns demonstrate that while a breeder's RTL predicts offspring quality, assortative mating by RTL does not enhance fitness, and a trade-off between different components of fitness may govern patterns of assortative mating by telomere length. They also illustrate how testing the adaptive value of only one parent's telomere length on either survival or reproductive success alone may provide equivocal results. [ABSTRACT FROM AUTHOR]