Using closed-circuit infrared camera to assess biparental provisioning behaviour and foraging pattern of house-farmed swiftlets (Aerodramus sp.)

Constraints in the capacity to brood, specifically supplying oxygen to aggregated embryo masses, is one of the mechanisms invoked to explain the association between small body size and brooding exhibited by marine invertebrates. We hypothesized that brooding costs may affect the capacity to supply oxygen to the brood, therefore constraining brooding to small body size. We ana- lyzed female brooding behaviour and patterns of oxygen availability in embryo masses of females carrying early and late stage embryos in 2 species of small size crabs: Pisoides edwardsi and Acan- thocyclus gayi. These species are between 3 and 10 times smaller than previously studied crab spe- cies. The costs of incubation were estimated by comparing oxygen consumption of nonbrooding and brooding females in each crab species. The same brooding behaviours reported for large body size species were performed by the 2 small species studied. However, behavioural patterns throughout embryo development were different between small and large body size species. Oxygen availability (% air saturation) never showed limitations in embryo aggregations in the 2 small crab species, in contrast to results from previous studies on large crabs. Another clear difference between brooders with small and large body size is the cost of oxygen provision, as no differences in oxygen consump- tion of brooding and nonbrooding females were found in the 2 small species. In contrast, oxygen con- sumption of brooding females is twice that of nonbrooding females in crabs of large body size. Our results provide direct evidence for the effects of adult size on the costs of providing oxygen to the brood, suggesting that brooding at large body sizes may not be related to the capacity to hold a brood, but to the capacity to provide oxygen to the embryos, and to the associated cost. Further, we discuss the effect of embryo size on female brooding behaviour and brooding costs.

Summary 1. Synchrony in the timing of births is thought to have evolved as a general predator avoidance strategy. In turtles, synchronous hatching may facilitate group emergence from the nest, which in turn, may limit predation by diluting an individual’s risk of predation or by simply swamping predators upon emergence. However, synchronizing hatching should not be easily achieved in natural nests because of thermal gradients affecting developmental rates. 2. We evaluated pipping synchrony in the painted turtle (Chrysemys picta), where the drive to hatch synchronously may be reduced, because in many populations, hatching and emergence are dissociated through hatchlings overwintering within a nest. 3. We also assessed developmental mechanisms through which synchrony occurs and explored potential trade‐offs between pipping synchrony and individual fitness by determining potential short and long‐term neuromuscular developmental costs to hatching prematurely. These data were also used to develop a theoretical model to determine how differential embryonic maturation rates affect hatching synchrony. 4. Underdeveloped embryos pipped much earlier than expected and at similar times to their more advanced sibs. In addition, a trade‐off between hatching synchronously and neuromuscular development (motility) was evident several days after hatching and up to 9 months later, after the overwintering period. 5. Synchronous hatching is an ancestral trait in turtles, but its relevance today is not solely for predator avoidance in all species. 6. Abiotic factors during incubation (e.g. temperature regime and moisture) have long‐term effects on reptiles during ontogeny but it is also clear that incubation behaviour is major factor for the persistence of these developmental costs.

We studied parental care in the Jacky Winter Microeca fascinans at Gluepot Reserve, South Australia, for one breeding season from 16 August to 9 November 2001, supplemented by observations on breeding and social behaviour in September 2012. We monitored ten nests in 2001, nine of which were attended by pairs and one by three adults, and watched three nests for a total of c. 117 hours. Female incubation constancy was 69%, duration of incubation sessions averaged 4.58 minutes and absences from the nest 2.07 minutes. Mean number of nest visits per hour by two pairs during the incubation period was 10.6 and for a group of three adults (two males, one female) was 15.8. Female care included brooding, feeding of nestlings, and nest-hygiene. Male care included delivering food to the sitting female, feeding the nestlings, nest-hygiene, nest-defence, and territoriality. Mean female brooding constancy was 55%. Mean number of feeding trips per hour by male and female combined for the entire nestling period was 14.6. Older young, 12, 13 and 14 days of age, received 21, 20, and 29 feeds/h respectively or one feed about every 2 minutes. Mean number of visits per hour by male and female combined to a nest with two young was 16.5 for Days 1–10 and 20.4 for Days 11–18 of the nestling period. High nest-predation is discussed in relation to nest placement and concealment, high nest visitation during incubation and nestling stages, anti-predator behaviour, nest-defence and types of predators, and re-nesting capacity, and compared with other Australasian robins and northern temperate and tropical songbirds. The small nest, small clutch-size, high nest failure, and anti-predator posture and mottled plumage of nestlings suggest that nest-predation is a strong selective pressure in the Jacky Winter. However, the moderately long nestling period, brood-size reduction, high rates of feeding young and nest visits by both male and female, and short and frequent incubation and brooding bouts on and off the nest relative to other robins are not consistent with nest-predation theory, and suggest behavioural responses to food availability and an ultimate response to food limitation. Incubation behaviour on and off the nest, parental care of young, nest visitation and other life-history traits that influence reproductive effort are discussed to elucidate the breeding strategy compared with other Australasian robins.

Assessing stress in wild populations is important in many ecological and conservation contexts because the physiological responses of individuals to stressors can be used to identify at-risk populations and the ability to respond appropriately to stressors is related to individual quality and fitness. Yet, one of the great challenges in ecophysiology is linking physiological measures in wild animal populations with changes in individual fitness. Here, we examined two indices of stress, namely, circulating baseline corticosterone concentration ([Cort]) and the heterophil:lymphocyte (H/L) ratio, in a long-lived seabird, the Nazca booby (Sula granti) and their relationship with current individual state and subsequent survival and residual and lifetime reproductive success. [Cort] was related to sex, age, and current reproductive effort in in that males, older birds, and birds currently engaged in a breeding attempt birds had higher [Cort]. [Cort] was negatively associated with survival to the next breeding season. The H/L ratio was not associated with the current state of birds but predicted cohort-specific long-term survival. Lifespan and reproductive performance are correlated in Nazca boobies; therefore, our results suggest that the H/L ratio may be useful as an indicator of overall fitness, while [Cort] can be used to predict current or near-term fitness in this species. We further propose the H/L [or neutrophil/lymphocyte (N/L)] Ratio-Fitness Hypothesis, which posits that this ratio is repeatable within individuals and are negatively associated with fitness. This hypothesis needs to be tested in Nazca boobies and other species, and when supported by empirical evidence, then these ratios could be a powerful monitoring tool for assessing population health or identifying at-risk populations.

Most birds incubate their eggs to allow embryo development. This behaviour limits the ability of adults to perform other activities. Hence, incubating adults trade-off incubation and nest protection with foraging to meet their own needs. Parents can either cooperate to sustain this trade-off or incubate alone. The main cause of reproductive failure at this reproductive stage is predation and adults reduce this risk by keeping the nest location secret. Arctic sandpipers are interesting biological models to investigate parental care evolution as they may use several parental care strategies. The three main incubation strategies include both parents sharing incubation duties (“biparental”), one parent incubating alone (“uniparental”), or a flexible strategy with both uniparental and biparental incubation within a population (“mixed”). By monitoring the incubation behaviour in 714 nests of seven sandpiper species across 12 arctic sites, we studied the relationship between incubation strategy and nest predation. First, we described how the frequency of incubation recesses (NR), their mean duration (MDR), and the daily total duration of recesses (TDR) vary among strategies. Then, we examined how the relationship between the daily predation rate and these components of incubation behaviour varies across strategies using two complementary survival analysis. For uniparental and biparental species, the daily predation rate increased with the daily total duration of recesses and with the mean duration of recesses. In contrast, daily predation rate increased with the daily number of recesses for biparental species only. These patterns may be attributed to two independent mechanisms: cryptic incubating adults are more difficult to locate than unattended nests and adults departing the nest or feeding close to the nest can draw predators' attention. Our results demonstrate that incubation behaviour as mediated by incubation strategy has important consequences for sandpipers’ reproductive success.

Summary1. Adolescent female ring doves (Streptopelia risoria) were injected with progesterone, estrogen or a combination of the two. Progesterone did not increase oviduct weights over the controls. Estrogen caused moderate increase, while the maximum increase was caused by synergism between estrogen and progesterone. 2. Eight-day priming with estrogen, followed by 2-day treatment with the estrogen-progesterone combination, caused oviduct growth as great as that caused by the 10-day treatment with the combined dose. On the other hand, priming with progesterone did not significantly augment the effect of 2-day treatment with the combination. 3. On the basis of these data and of a discussion of the mechanisms of nest-building and incubation behavior, it is suggested that the normal cycle includes a period of estrogen secretion (concurrent with nest-building) followed by progesterone secretion (associated with egg-laying maximal oviduct growth, and incubation behavior).

In the age of machine learning, building programs that take advantage of the speed and specificity of algorithm development can greatly aid efforts to quantify and interpret changes in animal behavior in response to abiotic environmental factors, like temperature. For both endotherms and ectotherms, temperature can affect everything from daily energy budgets to nesting behaviors. For instance, in birds environmental temperature plays a key role in shaping parental incubation behavior and temperatures experienced by embryos. Recent research indicates that temperatures experienced by embryos affect viability and are important in shaping fitness-related traits in young birds, sparking renewed interest in relationships among environmental factors, parental incubation behavior, and incubation temperature. Incubation behavior of birds can be monitored non-invasively by placing thermal probes into the nest and analyzing temperature fluctuations that occur as parents attend and leave the nest (on- and off-bouts, respectively). When other measures of temperature (e.g., ambient air or operative temperature) are collected simultaneously with incubation temperature it is possible to compare shifts in behavior with environmental changes. To improve analysis of incubation behavior using these large thermal data sets we developed a program, NestIQ, that uses machine learning to guide parameter optimization allowing it to track the behavior of diverse species. NestIQ's algorithm was tested using six species incubating in lab or field scenarios, that exhibit unique incubation patterns. This stand-alone and open source software is operated through a graphical user interface (i.e., no user programming is required) that provides important behavioral and thermal output statistics. Further, measures of environmental temperature can be imported alongside nest temperature into the program, which then reports various attributes of environmental temperature during shifts in parental behavior. This program will improve the ability of avian ecologists to interpret a critical parental care behavior that can be used across diverse incubation scenarios and species. Although specifically designed for quantifying avian incubation, NestIQ has the potential for broader applications, including basking and nesting behaviors of non-avian reptiles in relation to ambient temperature.

Aim To explore the determinants of island occupancy of 48 terrestrial bird species in an oceanic archipelago, accounting for ecological components while controlling for phylogenetic effects.Location The seven main islands of the Canary archipelago.Methods We obtained field data on population density, habitat breadth and landscape distribution in Tenerife, Fuerteventura and La Palma, aiming to sample all available habitats and the gradient of altitudes. In total, 1715 line transects of 0.5 km were carried out during the breeding season. We also reviewed the literature for data on occupancy, the distance between the Canary Islands and the nearest distribution border on the mainland, body size and endemicity of the 48 terrestrial bird species studied. Phylogenetic eigenvector regression was used to quantify (and to control for) the amount of phylogenetic signal.Results The two measurements of occupancy (number of occupied islands or 10 × 10 km UTM squares) were tightly correlated and produced very similar results. The occupancy of the terrestrial birds of the Canary Islands during the breeding season had a very low phylogenetic effect. Species with broader habitat breadth, stronger preferences for urban environments, smaller body size, and a lower degree of endemicity had a broader geographical distribution in the archipelago, occupying a larger number of islands and 10 × 10 UTM squares.Main conclusions The habitat‐generalist species with a tolerance for novel urban environments tend to be present on more islands and to occupy a greater area, whereas large‐sized species that are genetically differentiated within the islands are less widespread. Therefore, some properties of the ranges of these species are explicable from basic biological features. A positive relationship of range size with local abundance, previously shown in continental studies, was not found, probably because it relies on free dispersal on continuous landmasses, which may not be applicable on oceanic islands.

Climate-driven advances in the start of spring may result in a phenological mismatch between peak-prey abundance and the breeding season of secondary consumers. Phenological mismatch has been well-studied in insectivorous birds for which reproductive productivity is strongly linked to caterpillar abundance. The effects of mismatch on the productivity of dietary generalists, that forage on several types of prey, are less well-understood. Further, few studies have addressed questions about the effects of mismatch on survival, an important component of fitness that can be affected by breeding in sub-optimal conditions. We examined the relationship between phenological mismatch and fitness for a widespread generalist raptor, the American kestrel (Falco sparverius). In the first chapter, we collected productivity data from nest observations across the contiguous US and southern Canada and quantified phenological mismatch on each nest as the difference in days between the start of spring and clutch initiation. Then, we examined the relationship between mismatch, location, and productivity. Also, we investigated whether incubation behavior leading to hatching-asynchrony was related to phenological mismatch. Kestrels that laid eggs after the start of spring had fewer nestlings and higher rates of nest failure compared to kestrels that laid eggs before the start of spring. The strength of the mismatch effect depended on location. In the northeast, the number of fledglings per brood and rates of nest success were high for pairs nesting before the start of spring, but the effect of phenological mismatch was strongest here, with rapid declines in nest success associated with mismatch. Whereas, in the xi southwest, early-laying pairs had lower productivity and success relative to the northeast, but the effects of phenological mismatch were not as strong as the northeast. The effect of location is likely related to climatic constraints on the growing season and the time window for kestrel breeding that are becoming stronger in the northeast and weaker in the southwest. The timing of male incubation behavior was associated with hatching asynchrony, and males breeding after the start of spring were more likely to initiate incubation early as opposed to males breeding before the spring index date, suggesting that hatching asynchrony is a possible mechanism to cope with phenological mismatch. In the second chapter, we investigated the relationships between phenological mismatch and survival using mark-and-recapture data from two distinct, long-term study sites in Idaho and New Jersey where kestrel exhibit difference migration strategies. We created a multistate mark-recapture models to estimate the annual survival of adult (afterhatch- year) and juvenile (hatch-year or yearling) kestrels. For the multistate framework, we categorized the phenological mismatch of nests at each site “earlier” or “later” relative to the yearly median difference in days between clutch initiation date and the start-of-spring date, which was estimated at each nest box location. In addition, we included covariates for nesting success, sex, and minimum winter temperature anomaly in our survival models. Mismatch was associated with the survival of kestrels that produced young; however, the direction of this effect differed between populations. In Idaho, successful kestrels had higher survival when they bred “earlier” rather than “later.” In New Jersey, successful kestrels had higher survival when they bred “later” rather than “earlier." Differences in survival between sites may reflect differences in seasonality, climate change patterns, or consequences of migration strategies. For partially migrant xii populations (i.e, Idaho kestrels), mismatch may rapidly drive directional selection for birds to breed earlier by favoring survival and productivity, but for fully migrant populations (i.e., New Jersey) that have a limited window of time to reproduce, mismatch may create trade-offs between reproduction and survival. Mismatch did not affect the survival of adult birds with failed nests, and there was no difference in survival between hatch-year birds produced from “earlier” or “later” nests. In Idaho, males had higher survival rates than females and warmer winter temperatures positively correlated with survival in all age and sex classes. In New Jersey, sex and winter temperature did not explain survival. In sum, we found negative consequences of phenological mismatch on the fitness of American kestrels, generalist predator. For both productivity and survival, the effect of mismatch was more severe for kestrels in the northeast, where the breeding season is shorter and kestrels more migratory when compared to the west. These results demonstrate that duration of breeding season is an important factor to consider when assessing vulnerability to climate change, and that a generalist diet does not ensure resilience to phenological mismatch.

Incubation is an important component of avian parental care and slight changes in incubation temperature can affect offspring phenotype. Although many extrinsic and intrinsic factors may generate variation in incubation temperature, they remain underexplored under natural conditions. Using a robust data set encompassing 55 nests, 22 816 behavioral observations, and > 1 million paired ambient and egg temperatures, we describe the relationships among abiotic factors, female incubation behavior, incubation temperature, and incubation period for tree swallows Tachycineta bicolor . We report a large amount of individual variation in incubation behaviors and average incubation temperatures for our study population. The average on‐bout incubation temperature was 34.1°C, with daily egg temperatures ranging from 18.0–39.2°C. Females modulated the number of times they left the nest and the amount of time they stayed off the nest according to interactions between precipitation and temperature patterns. Models generated from our observations predicted that the number of female off‐bouts was the lowest under warm and dry conditions while more off‐bouts were taken under cold and dry or warm and wet conditions. During cold and dry conditions, females stayed off their nest ∼4 times longer than under warm and dry conditions. However, this pattern was reversed under periods of rainfall; females tended to take shorter off‐bouts when it was rainy and cold compared to longer off‐bouts during warmer rain events. Furthermore, variation in female behavior was associated with differences in overall incubation temperature such that females that maintained greater incubation constancy produced higher incubation temperatures at a given ambient temperature than those that displayed lower incubation constancy. Our results provide perspective on the timing of breeding, as some of the advantages of breeding early may be countered by cooler, early season temperatures and precipitation that cause reproducing females to favor self‐maintenance at a potential cost to optimal incubation temperatures for offspring development.

Coronary heart disease (CHD) originates early in life and numerous studies have shown inverse associations between body size at birth and CHD in adult life. Recently it has been shown that the increased risk for CHD associated with a small body size at birth is modified by growth during childhood. The greatest risk for CHD is noted in individuals with small body size at birth and who 'catch-up' in weight and body size during childhood. An increase in body weight and body mass index during the first year of life is however associated with a reduced risk of CHD. These recent findings add to the evidence that optimizing early growth is an important area in primary prevention of CHD. There are several potential mechanisms explaining the association between a non-optimal early growth and CHD. Behavioral, physiological, hormonal and genetic factors influence growth. Although socio-economic factors influence the risk of CHD, the association between slow fetal growth and CHD is not caused by confounding socio-economic factors. Biological programming -- the process whereby a stimulus during critical periods of development has long lasting or lifelong effects on metabolism -- is proposed to mediate the effects between early growth and adult diseases.

We studied avian breeding and molting activity in relation to rainfall, temporal fluctuations in food resource abundance, and food exploitation by birds, in four arid and semiarid tropical habitats in Venezuela. Twice a month we used mist to monitor changes in breeding and molting conditions of captured birds and forced them to regurgitate to determine their diet and feeding guild membership. Food abundance was assessed by measuring the flowering and fruiting seasonality of marked plants and by evaluating arthropod abundance with four different trapping methods. Flowering activity was limited largely to the wet season. Fleshy fruits, although produced year—round, were also more abundant in the rainy period. Anthropod abundance followed the same general pattern with numbers highest in the wet season and lowest in the dry season. Birds of all feeding guilds predominantly bred and molted during the wet season, synchronously with the highest abundance of most food resources. However, the diet analysis revealed a higher occurrence of arthropods coupled with a sharp decrease in the intake of vegetable matter during birds' breeding season. Consequently, we suggest that arthropod abundance is a crucial factor governing the timing of breeding activities, even in species that normally include a high proportion of nectar and fruits in their diet. We also postulate that, in tropical habitats receiving >1500 mm of rain per year, breeding in nectarivores and frugivores in the dry season may be related to the lower reduction in arthropod numbers over the less severe drought period.

Body size at birth has implications for the quality of individuals throughout their life. Although large body size is generally considered an advantage, the relationship between body size at birth and long-term fitness is often complicated. Under spatial or temporal variation in environmental conditions, such as the seasonally changing densities of Fennoscandian vole populations, selection should favor variation in offspring phenotypes, as different qualities may be beneficial in different conditions. We performed an experiment in which a novel hormonal manipulation method was used to increase phenotypic variance in body size at birth in the bank vole (Myodes glareolus). The effects of body size on the future fitness of young males and females were then studied at varying population densities in outdoor enclosures. Our results show that small body size at birth and high breeding density increase the survival costs of reproduction. However, there was no interaction between the effects of body size and density on survival, which suggests that the fitness effects of body size were strong enough to persist under environmental variation. Moreover, litter size and the probability of breeding were more sensitive to variation in breeding density than offspring size. Therefore, it is unlikely that individual fitness could be optimized by adjusting offspring body size to the prevailing population density through adaptive maternal effects. Our results highlight the significance of the costs of reproduction in the evolution of life-history traits, and give strong experimental support for the long-term fitness effects of body size at birth.

Diel changes in vertical and horizontal distribution of cladocerans in two deep lakes during early and late summer

From deer antlers to crab claws, weapons are some of the most elaborate and enormous structures in the animal kingdom. Within a species, weapon size generally increases with the size and condition of an individual, and those with larger weapons are usually better at fending off more diminutive competitors. Although it may seem desirable for all individuals to have large weapons, size varies greatly within a species. The ‘handicap principle’ proposes that the cost of bearing a weapon dictates the variation in weapon size. Smaller or less fit individuals pay more for weapons than larger or fitter animals, so smaller individuals tend to grow smaller weapons. Although popular, only a handful of studies have demonstrated experimental evidence that supports this theory. To test the handicap principle, Dinh and Patek studied a group of crustaceans known as snapping shrimp. Each shrimp has one enlarged claw that it uses as a weapon to fire imploding vapor bubbles at opponents during fights. Larger snapping shrimp have bigger enlarged claws and tend to win more contests. Males also have larger weapons than females, and this sex difference is amplified during the breeding season. Dinh and Patek studied weapon size in several species of snapping shrimp. Measurements showed that after controlling for body size, individuals with larger weapons had smaller abdomens, suggesting there is a tradeoff between weapon size and abdomen size. Furthermore, small males exhibited the steepest tradeoff, in line with the handicap principle. Snapping shrimp also showed sex-specific costs and benefits. After controlling for body size, females with larger weapons produced fewer and smaller eggs, while males with larger weapons were more likely to be paired with females and generally paired with larger females. This suggests that weapons are particularly burdensome to female shrimp and particularly beneficial to males, especially during the breeding season. These findings provide elusive evidence for the handicap principle and extend the theory to explain sex and seasonal differences in the size of snapping shrimp weapons. More broadly, the findings highlight the value of studying both male and female animal weapons when, historically, the focus has been on male weaponry.