Nest Visits Research Articles

Multi-level social organization and nest-drifting behaviour in a eusocial insect.

Stable social groups usually consist of families. However, recent studies have revealed higher level social structure, with interactions between family groups across different levels of social organization in multiple species. The explanations for why this apparently paradoxical behaviour arises appear to be varied and remain untested. Here, we use automated radio-tagging data from over 1000 wasps from 93 nests and social network analyses of over 30 000 nest visitation records to describe and explain interactions across levels of social organization in the eusocial paper wasp Polistes canadensis. We detected three levels of social organization (nest, aggregation and community) which exchange ‘drifter’ individuals within and between levels. The highest level (community) may be influenced by the patchiness of high-quality nesting habitats in which these insects exist. Networks of drifter movements were explained by the distance between nests, the group size of donor nests and the worker-to-brood ratios on donor and recipient nests. These findings provide some explanation for the multi-level social interactions, which may otherwise seem paradoxical. Fitness benefits across multiple levels of social organization should be considered when trying to understand animal societies.

Evidence of nest material kleptoparasitism in Worm-eating Warblers (Helmitheros vermivorum) in east-central Arkansas, USA.

Nest material kleptoparasitism likely evolved in birds to reduce the cost of searching for and collecting material themselves. Although nest material kleptoparasitism has been reported commonly in colonially nesting species, reports for solitary breeding species are infrequent, especially for neotropical migratory species. Here, we report potential and actual nest material kleptoparasitism in the Worm‐eating Warbler (Helmitheros vermivorum). We deployed video camera systems at passerine nests (n = 81) in east‐central Arkansas during summers 2011–2012. In one video, we observed a Worm‐eating Warbler stealing nesting material from a Hooded Warbler (Setophaga citrina) nest. One day later, we later observed a Worm‐eating Warbler landing within 0.5 m of the same warbler nest when the female was incubating, which possibly deterred a second theft of nesting material. In a third video recording, we observed another Worm‐eating Warbler landing within 1 m of an Indigo Bunting (Passerina cyanea) nest. As far as we could determine, neither of these latter two nest visits resulted in nest material kleptoparasitism. Potential benefits of nest material kleptoparasitism include reduced competition for limited nest materials, easy access to suitable material, reduced travel distance, and reduction of nest predation risk; however, costs include risk of attack by host or introducing parasites to one's nest. Importantly, this behavior could ultimately affect the behavioral and life history evolution of a species. We suggest further work should be conducted to determine the prevalence of nest material kleptoparasitism in Worm‐eating Warblers and other solitary breeding passerines, including efforts to quantify the benefits and costs of this behavior.

Sex Differences in Anti-Predatory Behaviour in Lined Seedeaters Sporophila lineola

Altricial birds face the challenge of defending their offspring against potential threats in a fixed location: their nest. In species with biparental care, both parents have an equal interest in defending their nest, although the sexes may differ in their investment in anti-predatory behaviours. We conducted a field experiment to investigate sex-asymmetry in anti-predatory behaviours in a breeding population of Lined Seedeaters Sporophila lineola, a small passerine that exhibits sexual dimorphism in adult plumage colour, in south-eastern Brazil. In Lined Seedeaters females are known to be solely responsible for nest building and incubation. Males help to feed the nestlings and are expected to assume the main role in performing anti-predatory behaviours. We presented stuffed models of nest predators (toucans Ramphastidae) and non-predators (pigeons Columbidae) at active nests and measured the number of alarm calls per minute, number of visits during the trial and latency to resume nest visits after the trial. Our results show that birds emitted alarm calls at higher rates when facing a predator than a control stimulus. Moreover, males generally emitted more alarm calls than females, irrespective of the treatment. Both parents did not visit the nest during the predator trials and they took longer to return to the nest after the model had been concealed than during the control trials. Although males seem to take the main role when it comes to responding to intruders (predator and non-predator), further studies, testing a bigger array of predatory stimuli, are needed to better test and understand sex asymmetry in risk-taking behaviours.

Why do nestling birds fledge early in the day?

In altricial birds, leaving the nest is a key life history transition associated with a high risk of mortality. Studies of numerous species have shown that young typically fledge early in the day, and it is often asserted that early fledging is important for survival; however, evidence for this hypothesis is limited. We used an automated monitoring system to obtain precise fledging times of 1582 young blue tits, Cyanistes caeruleus , from 230 nests. As expected, nestlings primarily fledged early in the day (84% fledged before midday). However, we found no evidence that early fledging was associated with higher postfledging survival (i.e. recorded the following autumn or later). We propose two alternative explanations for the morning peak in fledging. Hypothesis 1 is that some offspring reach a developmental threshold for fledging overnight and leave the nest early the next day. This is supported by our observation that offspring that fledged early in the day tended to be more developed than those that fledged later in the day, that is, they were older and had a high body mass (measured at 14 days of age) for their fledging age. Hypothesis 2 is that the timing of fledging is related to parental provisioning behaviour. Our results do not support this hypothesis. Parents reduced their nest visit rate over the course of the day, but offspring did not fledge earlier when their parents decreased their visit rate more strongly with time of day. In conclusion, our results do not support the notion that the time of fledging affects survival but suggest a link with nestling development. • In altricial birds, nestlings typically fledge early in the day. • This is often assumed to improve survival, but with little supporting evidence. • We monitored the precise fledging times of 1582 blue tits from 230 nests. • Fledging time was not associated with the probability of local survival. • Instead, fledging time was related to the developmental stage of nestlings.

Nestling Physiology Is Independent of Somatic Development in a Common Raptor, the American Kestrel (Falco sparverius).

AbstractAlthough many studies have documented the developmental trajectory of somatic traits in birds, few measure physiological traits, and even fewer document individual variation in developmental trajectory across ecological context. Hematological traits underlying aerobic capacity can be predictive of nestling survival, fledgling flight ability, and ultimately recruitment. This study aimed to assess individual variation in the developmental trajectory of two physiological traits that underlie aerobic capacity, hematocrit and hemoglobin concentration, in relation to somatic development and ecological context. Our study species, the American kestrel (Falco sparverius), is sexually dimorphic and therefore likely to show sexual variation in developmental trajectory and nestling maturity. We used lay date, year, brood size, nestling sex ratio, and parental nest visit rate to assess ecological context. Although somatic traits showed similar trajectories across nestlings, developmental trajectory for hematocrit and hemoglobin concentration showed individual variation not previously documented. This individual variation in developmental change, or trajectory, for physiological traits could not be explained by somatic development, sex, parental nest visit rate, lay date, year, brood size, or nestling sex ratio. However, we did find higher final hemoglobin concentration in 2018 and in nests with earlier lay dates. These findings demonstrate the importance of assessing physiological traits that capture aspects of individual quality distinct from somatic traits. Future studies are needed to understand the causes of individual variation in developmental trajectory, which cannot be explained by the ecological variables presented here, and the potential fitness consequences of this variation.

Sex‐specific effects of predation risk on parental care in a sexually dichromatic Neotropical songbird

Predation risk affects a broad range of bird behaviours, especially parental care. The adaptive behavioural changes presented by both parents, however, may differ according to different levels of predation risk suffered by each sex. This is especially prominent in sexually dichromatic species, where one of the sexes is more visually conspicuous and hence vulnerable to increased nest predation risk during nest visits. Here, we experimentally investigated how predation risk affects the parental behaviour of a sexually dichromatic Neotropical passerine, the blue‐black grassquit Volatinia jacarina. We used playbacks of known predators and non‐predatorial control sympatric species near nesting pairs in the field. Results show that grassquits modify their behaviour according to predation risk and that this behavioural response is sex‐dependent. Males decrease their nest visit times, become more discreet when moving towards the nest, and stop performing sexual displays after leaving the nest. In contrast, females tend to decrease latency to visit the nest and increase the duration of brooding bouts. These different sex responses reduce nest visual and acoustic detectability, since conspicuous males are readily spotted on nests and cryptic females camouflage nestlings and suppress begging calls. Although these behavioural changes might reduce predation risk, there might be a cost of reduced food load to nestlings and increased brood starvation risk. These changes in nesting activities illustrate the behavioural adaptability of passerines to ensure offspring survival in tropical high predation risk environments.

Threat recognition and response in an avian brood-parasite host from New Caledonia

AbstractNest predation and avian brood parasitism are the main sources of nest failure in many passerine birds. Large predators threaten both brood and parents, whereas brood parasites pose only a danger to eggs or nestlings. The fan-tailed gerygone Gerygone flavolateralis from New Caledonia is subjected to high rates of nest predation by the New Caledonian crow Corvus moneduloides (responsible for about 20–40% of predation) and moderate rates of brood parasitism by the shining bronze-cuckoo Chalcites lucidus (parasitizing about 18% of nests), which also depredates nests that are too advanced for parasitism (13% of nests). To test if fan-tailed gerygones are able to discriminate predators from brood parasites, we presented 3 bird models at active gerygone nests: a brood parasite/small nest predator (shining bronze-cuckoo), a large nest predator (crow), and a small non-native bird (common chaffinch Fringilla coelebs), which is unknown to the gerygone, as a control. We assessed the response of adult gerygones to the presentation of each model by measuring the minimum approach distance, number of alarm calls, number of attacks, and time to first nest visit after the presentation (latency). Adult gerygones often attacked the cuckoo, approached but never attacked the chaffinch and always avoided the crow. Latency was shorter after an attack response and during brooding, but similar among models. We did not find any link between the cuckoo model presentation and later ejection of cuckoo nestlings. We conclude that adult fan-tailed gerygones discriminate between different models and respond accordingly to the level of threat, but do not show awareness of parasitism risk and increase of nestling ejection rates following exposure to the cuckoo model.

Do Parental Feeding Rate and Feeding Synchrony Affect Nest Survival in a Songbird?

Nest predation risk is an important factor that may promote the evolution of adaptive parental reproductive strategies in animals. In altricial birds, where parents feed their offspring at the nest for a period of time, parent birds must balance the benefit from increased nest visits and the cost from increased nest predation resulting from their nest visits being detected by predators. Empirical evidence has shown a relationship between parental nest visits and nest predation risks, and parents have been found to be able to reduce the chance of being detected by predators by synchronizing their feeding visits while maintaining feeding rate unchanged. However, it remains poorly understood whether the relationships are universal to all species. We investigated whether nest survival is correlated with parental feeding rate and feeding synchrony in the silver-throated tit (Aegithalos glaucogularis), a songbird endemic to China. We found that parental feeding rate varied by brood size, nestling age and the time during the day, but feeding synchrony was unrelated to the above factors. Moreover, we showed no effect of parental feeding rate or synchrony on nest survival. The failure to find a relationship between parental feeding synchrony and nest survival seems exceptional because it is contrary to findings of previous studies. While there was likely a publication bias regarding previous studies, it is also possible that the evolution of feeding synchrony in different species has different explanations, or the complexity of the predator community and other factors affecting nest survival need to be considered in the analyses.

Urban resources limit pair coordination over offspring provisioning

The amount of care parents provide to the offspring is complicated by an evolutionary conflict of interest (‘sexual conflict’) between the two parents. Recent theoretical models suggest that pair coordination of the provisioning may reduce this conflict and increase parent and offspring fitness. Despite empirical studies showing that pair coordination is common in avian species, it remains unclear how environmental and ecological conditions might promote or limit the ability of parents to coordinate care. We compared the level of pair coordination, measured as alternation and synchrony of the nest visits, of house wrens Troglodytes aedon pairs breeding in a rural (10 nests) and a suburban (9 nests) site and investigated how differences in parental behaviours were related to habitat composition, prey abundance and how they ultimately related to reproductive success. We found that parents alternated and synchronized their nest visits more in the rural site compared to the suburban one. The suburban site is characterized by a more fragmented habitat with more coniferous trees and less caterpillar availability. Offspring from the rural site were heavier at fledging than at the suburban site. Taken together, these results suggest that environmental conditions play an important role on the emergence of coordinated parental care and that considering environmental variables is pivotal to assess the fitness consequences of parental strategies.

Flupyradifurone reduces nectar consumption and foraging but does not alter honey bee recruitment dancing

Foraging is essential for honey bee colony fitness and is enhanced by the waggle dance, a recruitment behavior in which bees can communicate food location and quality. We tested if the consumption of nectar (sucrose solution) with a field-realistic concentration of 4 ppm flupyradifurone (FPF) could alter foraging behavior and recruitment dancing in Apis mellifera. Foragers were repelled by FPF. They visited the FPF feeder less often and spent less time imbibing sucrose solution (2.5 M, 65% w/w) with FPF. As a result, bees feeding on the FPF treatment consumed 16% less nectar. However, FPF did not affect dancing: there were no effects on unloading wait time, the number of dance bouts per nest visit, or the number of dance circuits performed per dance bout. FPF could therefore deter bees from foraging on contaminated nectar. However, the willingness of bees to recruit nestmates for nectar with FPF is concerning. Recruitment can rapidly amplify the number of foragers and could overcome the decrease in consumption of FPF-contaminated nectar, resulting in a net inflow of pesticide to the colony. FPF also significantly altered the expression of 116 genes, some of which may be relevant for the olfactory learning deficits induced by FPF and the toxicity of FPF.

Do repeated captures and handling affect phenotype and survival of growing Snow Petrel (Pagodroma nivea)?

In vertebrates, developmental conditions can affect not only fledging success but also the phenotype of the offspring, with potential long-term consequences on adult performance. However, surprisingly the potential impact of anthropogenic disturbance on developing chicks is rarely investigated, notably in Antarctic wildlife. In this study, we specifically investigated the effects of repeated nest visits, capture, and handling on offspring survival and several complementary offspring phenotypic traits in the Snow Petrel (Pagodroma nivea) chicks after thermal emancipation. We did not find any significant effect of our disturbance protocol on the morphology (body size, body mass, body condition), the physiology (breath rate, stress-induced corticosterone levels) and the behaviour (defense behaviour) of developing Snow Petrels. This specific disturbance protocol did not have any significant effect on chick survival, but there was a non-significant trend towards a lower survival for the disturbed group (p = 0.1006), which showed an especially high mortality during a period of repeated snow storms. To conclude, investigator disturbance seems to have little effect on Snow Petrel chicks after thermal emancipation, but to remain cautious, we recommend to avoid capture and handling of Snow Petrel chicks during or soon after inclement weather.

Ecology of the Golden Eagle in Mongolia, Part 2: Prey

From nearly 600 prey remains collected in 95 nest visits from extreme eastern to extreme western Mongolia, we found that Golden Eagles (Aquila chrysaetos) consumed a high percentage (20%) of predatory birds and mammals. The prey delivered to nests was also very diverse. As expected, the eagles preyed on hares (Lepus tolai, 12%) and marmots (Marmota spp., 38%), but 15% of their prey were foxes (Vulpes spp.). We identified 30 species of birds, including six species of raptors, among the prey remains. Surprisingly, ground squirrels (Spermophilus spp., 5%) were underrepresented and even in vole (Lasiopodomys and kin) irruption years/zones, voles and other small rodents (4%) were seldom found in the nests. Loss of rodents and other prey due to aerial broadcasting of rodenticides likely affects Golden Eagles in Mongolia, as do persecution, mortality from electrocution, and removal of eagles for falconry and tourist trade. All these need careful quantification.

Evaluation of nesting behavior of individual laying hens in an enriched colony housing by using RFID technology

The US egg industry is progressively adopting alternative housing systems for laying hens. Provision of nesting places accommodates natural behaviors and may improve the welfare of the laying hen. However, some fundamental questions remain about nesting behaviors of hens under different housing conditions, which would impact system design and management. For instance, how long does a hen use nest per day for egg laying or nest exploration? How many hens nest simultaneously? In such schemes, information on hens’ behavioral and production responses of hens remains relatively sparse. The primary objective of this work was to demonstrate that RFID technology can be used to continuously quantify dynamic nesting behaviors of individual laying hens in a 60-hen enriched colony housing (ECH). Results show that hens spent on average 63.7±1.4 min (mean±SE) in the nest box and made 23.4±0.7 nest visits during a 16 h daily light period. Time spent in and visits to the nest box during the 6 h laying period accounted for 56% and 45% of the light-period value, respectively. Maximum nest occupancy was 29.0%±0.4%. Three distinct phases of egg production in nest boxes were observed: initial (1.5 h), peak (3.2 h, egg laying rate of 0.24±0.01 eggs/min), and late (1.3 h). The majority (95.1%±0.6%) of the daily eggs were laid in the nest box. Considerable variations in nesting behavior among individual hens and day-to-day variations for a given hen were observed. The RFID system will enable researchers to examine the impacts of resource allocations on nesting behaviors of laying hens in alternative hen housing. Keywords: animal welfare, egg production, RFID, alternative hen housing, individual behaviors DOI: 10.25165/j.ijabe.20191206.5129 Citation: Oliveira J L, Xin H W, Wang K L, Zhao Y. Evaluation of nesting behavior of individual laying hens in an enriched colony housing by using RFID technology. Int J Agric & Biol Eng, 2019; 12(6): 7–15.

Distribution of Experimentally Increased Costs of Parental Care Among Family Members Depends on Duration of Offspring Care in Biparental Birds

Biparental care systems are a valuable model to examine conflict, cooperation, and coordination between unrelated individuals, as the interactions between the parents determines their fitness. Temporarily handicapping one parent induces a higher cost of providing care and is a widespread experimental technique for testing coordinated responses to changes in the costs of parental care in birds. However, dissimilarity in experimental designs of handicapping studies has hindered interspecific comparisons of the patterns of cost distribution between parents and their offspring. Here we apply a comparative approach by handicapping a parent at nests of five altricial bird species using the same experimental treatment. Across species, handicapped parents reduced their nest visitation rate, indicating increased costs of parental care for the manipulated parent. Unexpectedly, the partners of handicapped individuals did not compensate for the reduction in care, and the increased costs were subsequently passed to their offspring. The strength of this effect was mediated by the total duration of offspring care; in species with long care periods, the offspring were passed a greater share of the additional cost. This effect was evident in both changes to nest visitation rates and the body mass gain of the nestlings. Surprisingly, these responses were independent of life history pace (i.e., adult survival and fecundity). While most studies of the costs of parental care focus on the trade-off between current and future reproduction or survival (intra-individual trade-offs), our study highlights that a greater attention to inter-generational trade-offs is warranted, particularly in species with prolonged parental care. Moreover, our findings demonstrate that parental care decisions may be weighed more against physiological workload constraints than against future prospects of reproduction, supporting evidence that avian species may devote comparable amounts of energy into survival, regardless of life history pace.

Do Parents Synchronise Nest Visits as an Antipredator Adaptation in Birds of New Zealand and Tasmania?

Birds with altricial offspring need to feed them regularly, but each feeding visit risks drawing attention to the nest and revealing its location to potential predators. Synchronisation of visits by both parents has been suggested as a behavioural adaptation to reduce the risk of nest predation. Under this hypothesis, higher risk of nest predation favours greater synchrony of parental feeding visits. We investigated this prediction over three timescales using nestling provisioning data from 24 passerine species in Tasmania and New Zealand. We estimated the extent to which parents actively synchronised their visits to the nest by comparing observed patterns of synchrony with those expected to occur at random. We found that in general, species did not synchronise visits more often than expected by chance. Species varied in the tendency to synchronise visits, but this variation was not explained by likely predation pressure in the distant evolutionary past: New Zealand endemic species, which evolved in the absence of mammalian nest predators, synchronised their visits as often as species which evolved with more diverse predatory guilds. Nest predation risk has increased over time in New Zealand due to introduced predators, but synchrony in visits also was not explained by manipulated predation risk: visit synchrony was equivalent between a predator-removal site and a site where predators remained. However, within one New Zealand species, visit synchrony was higher for mainland populations, which have been exposed to predatory mammals for c.800 years, than for a population on an offshore island to which predatory mammals were never introduced. We conclude that breeding birds may have some capacity to adapt the synchrony with which they provision over short evolutionary timescales. However, the lack of synchrony in most species suggests that either asynchrony provides benefits that outweigh the greater risk of predation, or synchrony incurs costs not compensated by reduced predation.

Who pays the bill? The effects of altered brood size on parental and nestling physiology

Current life history theory suggests that during times of extreme energetic demand, animals may need to trade off physiological capacity of certain functions to maintain other more important biological functions. This might be especially true during reproduction, as parents try to balance their current reproductive demands with the maintenance of themselves and their offspring, while also considering their future fitness. Here, we experimentally manipulated the brood size of black-capped (Poecile atricapillus) and boreal (Poecile hudsonicus) chickadees, giving them ± 2 nestlings (increased/decreased group) or leaving their nest at the same size (without manipulation; natural comparator group). Parents did not adjust their field metabolic rate to reflect the new brood size; however, nest visitation rate was higher in the decreased group. We found little difference between groups in terms of parental body composition or inflammatory response, with the exception that parents in the decreased group had a higher mass. Nestlings in the increased brood group had lower masses over the course of growth, including right before fledging. The manipulation also appeared to have an impact on tarsus length, but was best explained by a combination of group, species, hatch order and interactions. Nestlings in the decreased group had lower circulating IgY antibodies , but the manipulation had a minimal impact on inflammatory response. We found that, when parents were challenged to work harder, instead of altering aspects of their own physiology, the parents pushed the costs onto their nestlings, resulting in lower quality offspring.

Light data from geolocation reveal patterns of nest visit frequency and suitable conditions for efficient nest site monitoring in Common Swifts Apus apus

ABSTRACTCapsule: We developed a protocol for efficient monitoring of potential Common Swift Apus apus nest sites which considers variation in nest visit frequency across the breeding season and in relation to time of day and weather.Aims: To investigate patterns of nest visit frequency in Common Swifts in order to improve the efficiency and reliability of the monitoring of nest sites threatened by building renovations.Methods: We derived information on nest attendance from light data recorded by geolocators from ten adult Common Swifts during three breeding seasons (n = 686 individual sampling days) and analysed how nest visit frequency varied across the breeding season and in relation to time of day and weather.Results: The mean nest visit frequency was 5.63 visits per bird per day (0.32 visits per hour of daylight). The daily number of visits was highest at the beginning of July during chick-rearing. Moreover, it was positively correlated with temperature and negatively correlated with rainfall and wind speed. Nest visit frequency showed a distinct peak around sunset, while also being relatively high in the morning and around noon.Conclusion: We recommend monitoring potential Common Swift nest sites in Central Europe between the end of June and mid-July during good weather between 0.50 and 7.75 h after sunrise or between 3.00 h before sunset and sunset, when observation bouts of 0.5–2.0 h provide an encounter probability greater than 90%. Our study shows that repurposing geolocator light data – usually used to study bird migration – for investigating nest attendance in cavity-breeding birds can provide important information for bird conservation.

Use of passive radio frequency identification technologies to monitor nest usage in the northern carmine bee-eater (Merops n. nubicus).

The use of radio frequency identification (RFID) technology is common in animal-monitoring applications in the wild and in zoological and agricultural settings. RFID is used to track animals and to collect information about movements and other behaviors, as well as to automate or improve husbandry. Disney's Animal Kingdom® uses passive RFID technology to monitor nest usage by a breeding colony of northern carmine bee-eaters. We implemented RFID technologies in various equipment configurations, initially deploying low-frequency (LF) 125 kHz RFID and later changing to high-frequency (HF) 13.56 MHz RFID technology, to monitor breeding behavior in the flock. We installed antennas connected to RFID readers at the entrances of nest tunnels to detect RFID transponders attached to leg bands as birds entered and exited tunnels. Both LF-RFID and HF-RFID systems allowed the characterization of nest visitation, including the timing of nest activity, breeding pair formation, identification of egg-laying females, participation by nonresidents, and detection of nest disruptions. However, we collected a substantially larger volume of data using the increased bandwidth and polling speed inherent with HF-RFID, which permitted tag capture of multiple birds simultaneously and resulted in fewer missed nest visits in comparison to LF-RFID. Herein, we describe the evolution of the RFID setups used to monitor nest usage for more than 7 years, the types of data that can be gained using RFID at nests, and how we used these data to gain insights into carmine bee-eater breeding behavior and improve husbandry.

Alternation of nest visits varies with experimentally manipulated workload in brood-provisioning great tits

In species with biparental care, the amount of care devoted to offspring is affected by the negotiation rules that the parents adopt. Recently, turn taking in provisioning visits has been proposed as a negotiation rule by which parents respond to their partner's behaviour, which results in a perfect alternation of the nest visits by the parents. Empirical evidence suggests that parents do not strictly alternate their visits, and, so far, this imperfect alternation has received no experimental investigation. In this study, we tested whether alternation of nest visits might be subject to time constraints affecting the ability of parents to strictly take turns. We manipulated the workload of 15 great tit, Parus major, pairs using a short-term brood size manipulation. Parental nest visits alternated more in reduced than control and enlarged broods. To understand whether this variability could be caused by changes in turn taking, we explored the rate and regularity of the parents' intervisit intervals. Treatment differences in alternation were still present when controlling for the rate and regularity of the visits by each of the two parents, suggesting that workload also affected alternation via the temporal sequence of the intervals (e.g. via turn taking). Our results show that alternation of nest visits varies in response to workload and is not merely a by-product of variation in visit rate or regularity.

Pair coordination is related to later brood desertion in a provisioning songbird

Raising a family is not free of conflict for parents, as each parent benefits when its partner provides more care for the offspring. Resolving this conflict requires cooperation between the parents. One way to achieve such cooperation might be to coordinate parental provisioning by synchronizing (i.e. returning to the nest at the same time) or alternating (i.e. taking turns) offspring provisioning at the nest. Empirical studies in birds indicate that pair coordination of the nest visits is common; however, it is unknown whether this behaviour is directly related to different outcomes of sexual conflict, such as brood desertion. We used the rock sparrow, Petronia petronia, a species with high levels of sexual conflict, to explore whether alternation and synchrony of the nest visits were related to later brood desertion. Pairs with no desertion alternated and synchronized their nest visits more than pairs in which one sex deserted. This difference in coordination was not simply a by-product of differences in provisioning by the parents. Synchrony of the visits also increased with offspring age in the pairs with no desertion. We provide evidence, for the first time to our knowledge, that the degree of parental coordination is strongly associated with the ultimate consequence of sexual conflict, brood desertion, supporting the idea that coordination in parental behaviour might promote conflict resolution.