Much of the literature on owner-dog attachment and the influence of personality on the owner-dog relationship has originated in Europe, with few studies in North America. To address this imbalance, 29 owner-dog dyads from a Canadian population were tested in the Strange Situation Test (SST) and owners completed assessments of their own personalities (NEO-FFI-3), the personalities of their dogs (MCPQ-R), and their level of attachment to their dogs (DAQ). Attachment scores were comparable to those in previous research, and all owner-dog dyads were deemed to be securely attached. However, no predicted “matching” of seemingly analogous personality traits (e.g., human and dog Neuroticism) was found, and there was no relationship between dog personality and attachment behaviours during the SST. In contrast, owners with higher Extraversion scores initiated more contact with their dogs in the first reunion episode of the SST (following separation). Owners scoring low on Openness and/or Neuroticism had dogs with higher scores for Training Focus, suggesting that these dogs could more easily attend to a calm, stable owner. Owners who scored high in Openness had dogs with lower Amicability scores, possibly indicating more tolerance of a less desirable dog trait by such owners. Differences between the findings of this study and those conducted in Europe suggest that more emphasis should be given to the possible impact of cultural variation on the behaviours of and perceived relationships between owners and their dogs.

Kleptoparasitism is a foraging strategy where one individual steals a procured food item from another individual. Individual kleptoparasites can optimize their foraging strategy by targeting more profitable hosts or by modifying their behaviour to expend less energy than they would by foraging independently. Herring gulls, Larus argentatus, kleptoparasitize Atlantic puffins, Fratercula arctica, by intercepting adults as they return to their burrows with fish for their chicks. While this system has been studied extensively, much remains unknown, particularly from the herring gull's perspective. We tested predictors of herring gull host choice and the probability of success during kleptoparasitic attacks by conducting 73 30-minute focal samples of individual herring gulls at a breeding colony in Newfoundland, Canada. We recorded each puffin that approached the focal gull, categorizing them according to prey type carried, whether or not they landed, and whether or not they were attacked. For those puffins that were attacked, we also noted whether the gull succeeded in obtaining prey. Herring gulls did not attack puffins at random, but, rather, preferentially attacked puffins that carried larger prey, had already completed their landing, and landed closer to and/or in front of the gull. Gulls tended to be more successful at stealing a puffin's food when they attacked landed puffins and made physical contact with the puffin, but not when the puffin landed closer to them or when they were oriented towards the puffin. These findings suggest that herring gulls optimize their kleptoparasitic foraging strategy by targeting more profitable hosts. (C) 2020 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Mates of biparental species share parental care but they are also predicted to try, within limits, to push for more offspring care from their partners. Here we test (a) whether mates will attempt to exploit their partners less often when resources are scarce so as to not push their partners to their abandonment threshold and (b) whether there are differences in exploitation and compensation strategies of low and high quality partners where the quality assessment is based on within-pair differences in chick-provisioning rates. The same 14 pairs of common murres were observed in a year when capelin fish (the main prey species) were abundant (match year) and in a second year when capelin did not arrive inshore to spawn until the second week after hatching (mismatch year). One murre parent always attends the chick and, in the most common type of interaction, the returning parent feeds the chick, and takes over the brooding role. We consider nest relief interactions to be irregular if they did not follow this sequence for determining which parent will continue or take on the lower-energy brooder role. Two types of irregular nest reliefs were examined: (a) the returning bird does not bring a fish and (b) the brooding bird does not allow a brooding changeover even when the returner brings a fish. Rates of irregular nest reliefs and total visit time increased in the mismatch year after capelin arrived inshore, suggesting that longer co-attendance in good conditions reflects negotiation, rather than the increased resting or “loafing” time as previously proposed. High provisioners initiated fewer irregular nest reliefs than their low provisioning partners during favorable conditions but increased to comparable levels when resources were scarce. Partners' attempts to brood without provisioning were less often refused during unfavorable feeding conditions, suggesting that murres compensated for their mates when they could. The observation that rates of irregular nest reliefs changed with resource availability suggests that negotiation occurs throughout chick rearing and is not a set “sealed bid” at the onset.

We outline the progress on the hormonal basis of human paternal behavior during the past twenty years. Advances in understanding the roles of testosterone, prolactin, oxytocin and vasopressin in fathering behavior are described, along with recent research on hormonal interactions, such as those between testosterone and cortisol, and testosterone and the peptide hormones. In addition, we briefly describe the recent leaps forward in elucidating the neurobiological and neuroendocrine basis of fatherhood, made possible by fMRI technology. Emerging from this literature is a developing and complicated story about fatherhood, highlighting the need to further understand the interplay between behavior, physiology, social context, and individual genetic variation. Given the changing roles of parents in many societies, the continued growth of this research area will provide a strong empirical knowledge base about paternal behavior on which to create policies promoting fathers' involvement in their infants' lives.

Behaviorally, attachment is demonstrated when one individual maintains close proximity to another individual and shows distress upon separation. For 29 owner-dog dyads, we employed a modified Ainsworth’s Strange Situation Test (SST) to investigate whether both members would show a physiological reaction to separation. Dogs experienced a series of separation from and reuniting events with their owners and were introduced to a stranger. Before and after the SST, saliva samples were taken from each dyad to measure stress-related analytes: cortisol (CORT) and chromogranin A (CgA). Dogs exhibited attachment behaviors toward owners as evidenced by more time spent in close proximity, more contact initiated and less time spent near the door, compared to episodes with the stranger. Dogs that initiated more contact with their owners in re-uniting episodes had lower CgA than dogs that initiated less contact, but their owners had higher CgA levels. Also during re-uniting episodes, dogs and owners spent more time near each other when owner CgA levels were low, owner CORT levels were high, and the dog had owner-reported separation anxiety. During the episodes alone with the stranger, dogs with higher CORT spent more time with the stranger. Finally, dogs’ initial CgA levels were correlated with their owner’s initial CORT levels, and dog final CORT levels were correlated with their owners’ final CORT levels, suggesting some hormonal synchrony within the dyad. As all owner-dog dyads were assessed as securely attached, attachment style differences could not explain variation in hormonal or behavioral results. These results suggest that dogs may respond to owner hormonal state and/or behavior and demonstrate that individual differences in responses to a behavioral challenge reflect the stress physiology of both dogs and their owners.

Prey availability around seabird breeding colonies is often unpredictable, with prey fluctuating in both abundance and distribution. This study examined the effects of natural and experimentally altered food intake on growth and physiological condition in Atlantic puffin Fratercula arctica chicks during 3 breeding seasons. Previous studies have shown that food-supplemented chicks generally do not gain more mass than control chicks, because parents of food-supplemented chicks reduce their provisioning effort in response to the decreased food requirements of their offspring. In contrast, food-supplemented chicks in this study gained significantly more mass per day and had greater tarsus and wing growth than control chicks. Consistent with available information on capelin spawning, our results suggest that prey availability was generally so poor that parents could not reduce provisioning effort, even when extra food was provided. Corticosterone was significantly higher in control chicks compared with food-supplemented chicks, which is consistent with some, but not all, previous studies. Chicks had lower mass when prey availability was poor, but this was associated with high corticosterone levels only when weather conditions were also poor. These results suggest that measuring multiple fitness indices can be useful for determining overall environmental conditions and can provide insight into how puffins are adjusting to changes within their ecosystem.

Seabird parents use a conservative breeding strategy that favours long-term survival over intensive parental investment, particularly under harsh conditions. Here, we examine whether variation in several physiological indicators reflects the balance between parental investment and survival in common murres (Uria aalge) under a wide range of foraging conditions. Blood samples were taken from adults during mid-chick rearing from 2007 to 2014 and analysed for corticosterone (CORT, stress hormone), beta-hydroxybutyrate (BUTY, lipid metabolism reflecting ongoing mass loss), and haematocrit (reflecting blood oxygen capacity). These measures, plus body mass, were related to three levels of food availability (good, intermediate, and poor years) for capelin, the main forage fish for murres in this colony. Adult body mass and chick-feeding rates were higher in good years than in poor years and heavier murres were more likely to fledge a chick than lighter birds. Contrary to prediction, BUTY levels were higher in good years than in intermediate and poor years. Murres lose body mass just after their chicks hatch and these results for BUTY suggest that mass loss may be delayed in good years. CORT levels were higher in intermediate years than in good or poor years. Higher CORT levels in intermediate years may reflect the necessity of increasing foraging effort, whereas extra effort is not needed in good years and it is unlikely to increase foraging success in poor years. Haematocrit levels were higher in poor years than in good years, a difference that may reflect either their poorer condition or increased diving requirements when food is less available. Our long-term data set provided insight into how decisions about resource allocation under different foraging conditions are relating to physiological indicators, a relationship that is relevant to understanding how seabirds may respond to changes in marine ecosystems as ocean temperatures continue to rise.

In species with biparental care, pairs share a cooperative interest in offspring survival but may be in conflict over their relative investments, as reported in recent turn-taking studies of chick-provisioning birds. Turn-taking in Common Murres (Uria aalge) involves the foraging bird returning to the colony to provision the chick and the brooding parent departing. We examined whether Common Murres in poor condition had slower or more irregular turn-taking behavior, as has been documented in Common Murres equipped with geologgers. Irregularities include the brooding bird not trading parental roles with its returning mate or a bird returning to the colony without a fish. Irregular turntaking sequences generally took longer than normal turn-taking sequences and differed in the rate and synchrony of allopreening, the main interactive behavior between mates. There was a delayed onset of allopreening when nest reliefs were protracted, whereas returners that did not bring a fish started allopreening sooner than either their brooding partners or other returners that brought a fish. Common Murres in better condition (higher body mass and lower lipid metabolite levels) left the colony sooner after their returning mates fed the chick compared to Common Murres in worse condition. Birds with higher chick-feeding rates brought fish back in more visits, which suggests that these were higher-quality birds. When birds vary in their turn-taking ceremonial behaviors, they may be negotiating by providing their partners with cues about their condition. Since Common Murres have long-term pair bonds and both parents are necessary to raise offspring, mates should respond to information from their partners if they can do so without compromising their own condition beyond a critical threshold.

In order to fully understand factors that affect animals during their annual cycle, it is important to measure physiological and behavioral responses to environmental conditions in multiple seasons. We tested the hypothesis that corticosterone levels (CORT) are affected by spatial and temporal variations in marine environmental conditions by measuring levels in the feathers (grown outside of the breeding season) and blood (collected during the breeding season) of an abundant North Pacific seabird, the rhinoceros auklet Cerorhinca monocerata. Birds involved in our study bred on three widely dispersed colonies in three years in which oceanographic conditions differed markedly. Combined nitrogen ( δ 15 N) and carbon ( δ 13 C) stable isotope values in blood differed among colonies, while values in feathers did not, suggesting that individuals from the three colonies were segregated during the breeding season (as expected from foraging range around breeding colonies), but not during the nonbreeding period (as expected from genetic homogeneity). CORT showed the same pattern of dichotomy; of particular note, but contrary to our a priori prediction, blood CORT levels were higher in auklets that bred on a colony in which early chlorophyll- a bloom in local waters suggested good feeding conditions, than in auklets that bred on a colony with later local chlorophyll- a bloom. Also contrary to prediction, feather CORT was higher in a year featuring favorable, cold-water La Niña conditions than in a year of unfavorable, warm-water El Niño conditions; values in a third, moderate year were intermediate. We conclude that CORT levels are affected by spatiotemporal variation in marine environmental conditions, but relationships appear to depend heavily on context and thus require careful interpretation and more study.

This article is part of a Special Issue "Parental Care".We review recent research on the roles of hormones and social experiences on the development of paternal care in humans and non-human primates. Generally, lower concentrations of testosterone and higher concentrations of oxytocin are associated with greater paternal responsiveness. Hormonal changes prior to the birth appear to be important in preparation for fatherhood and changes after the birth are related to how much time fathers spend with offspring and whether they provide effective care. Prolactin may facilitate approach and the initiation of infant care, and in some biparental non-human primates, it affects body mass regulation. Glucocorticoids may be involved in coordinating reproductive and parental behavior between mates. New research involving intranasal oxytocin and neuropeptide receptor polymorphisms may help us understand individual variation in paternal responsiveness. This area of research, integrating both biological factors and the role of early and adult experience, has the potential to suggest individually designed interventions that can strengthen relationships between fathers and their partners and offspring.

Glucocorticoid levels measured in the blood of animals reflect hypothalamic-pituitary-adrenal (HPA) activity in response to predictable and unpredictable changes. In birds, circulating corticosterone is incorporated into growing feathers and provides an integrated measure of HPA activity over the period of feather growth. Measuring corticosterone in feathers can provide insight into the physiological state of birds during times when they are unavailable for blood sampling (e.g., during migratory or non-breeding periods of the annual cycle). Building upon studies that used radioimmunoassay or liquid chromatography, we used a commercially available enzyme immunoassay kit to measure corticosterone in feathers of nestling Atlantic Puffins (Fratercula arctica) on Gull Island, Newfoundland, Canada, in 2012, and demonstrate the benefits of sample preparation via acetonitrile/hexane purification. We used this method to measure corticosterone in feathers of Atlantic Puffin chicks that experienced differences in mass gain in a supplementary feeding study. We found a positive relationship between feather corticosterone and mass gain, and a negative relationship between feather corticosterone and pre-treatment body condition. Because feathers were growing prior to and during the supplementary feeding period, our results also suggest that extracting seabird feather samples with acetonitrile/hexane (in addition to methanol) prior to measuring corticosterone with enzyme immunoassay is beneficial, and, as reported in previous studies, blood and feather corticosterone values reflect different measures.RESUMEN Medicion de corticosterona en plumas utilizando extraccion por acetonitrilo/hexano y inmunoensayos enzimaticos: niveles de corticosterona en las plumas de Fratercula artica suplementados en su alimentacion Los niveles de glucocorticoide medidos en la sangre de animales representan la actividad del hipotalamo-pituitario-adrenal (HPA) en respuesta a cambios predecibles e impredecibles. En aves, la corticosterona que circula es incorporada durante el crecimiento de las plumas y provee una medida integrada de la actividad HPA a lo largo del periodo de crecimiento de la pluma. Medir la corticosterona en las plumas puede proveer informacion a cerca del estado fisiologico de las aves durante periodos en los que no estan disponibles para la toma de muestras de sangre (e.g. durante la migracion o durante periodos no reproductivos del ciclo anual). Basandonos en estudios en los que utilizaron radio-inmunoensayos o cromatografia liquida, utilizamos un kit de inmunoensayos enzimaticos disponible comercialmente para medir los niveles de corticosterona en las plumas de polluelos de Fratercula artica en las isla de Gull, Terranova, Canada, en 2012, con el fin de demostrar los beneficios de la preparacion de las muestras a traves de la purificacion con acetonitrilo/hexano. Utilizamos este metodo para medir la corticosterona en las plumas de los polluelos de Fratercula artica que experimentaron un incremento en el tamano corporal debido a un estudio de suplementos alimenticios. Encontramos una relacion positiva entre la corticosterona de las plumas y el incremento en el tamano corporal, ademas de una relacion negativa entre la corticosterona en las plumas y la condicion corporal previo al tratamiento. Debido a que las plumas estaban en etapa de crecimiento durante el periodo previo y durante la alimentacion suplementaria, nuestros resultados sugieren que los niveles de corticosterona en las plumas fueron influenciados por el estatus nutricional. Nuestros resultados tambien sugieren que la extraccion de muestras de plumas de aves oceanicas utilizando acetonitrilo/hexano (en adicion al metanol) previo a la medicion de la corticosterona con inmunoensayo enzimatico, es beneficial, y consistente a lo reportado en estudios previos, los niveles de corticosterona en la sangre y en las plumas reflejan diferentes medidas.

Need and hunger models of honest begging predict that lower-quality offspring should call more, or beg, to signal their poor body condition or hunger. In contrast, quality models of begging predict that offspring of higher fitness should call more, or boast, to signal their viability to parents. We observed 2 types of calls in Atlantic puffin (Fratercula arctica) chicks: a shorter peep call and a longer screech call. Poorly fed chicks screeched during a higher proportion of parental visits than well-fed chicks. Food-supplemented chicks showed a decrease in the proportion of food visits with screech calls, whereas control chicks did not. Chicks in good body condition peeped more than chicks in poor body condition and these chicks showed a greater increase in the peep call rate after supplemental feeding than chicks that started off in poorer condition. Screech calls may signal need and/or hunger to parents, whereas peep calls may signal chick quality. This combination of signals should allow parents to make strategic resource-based decisions, allocating more food to hungry or lower-quality chicks when resources are abundant and preferentially feeding high-quality chicks when resources are scarce.

Timing reproduction to overlap with peak prey availability is vital to success for many species. This may be especially true for species that rely on one or a few prey species that exhibit strong seasonal peaks in abundance. Any mismatch must be mediated by parents that provision offspring through flexible behavioral changes within the bounds of their physiological tolerances. In Newfoundland, common murre Uria aalge breeding coincides with the inshore movement of capelin Mallotus villosus—their primary prey—such that peak prey availability overlaps with chick‐rearing, the most energy demanding phase of breeding. We use colony‐based observations and temperature‐depth recorders to track the behavioral responses of murres to temporal match and mismatch with capelin availability. Activity budgets, daily energy expenditure (DEE) and chick‐provisioning rates were constant across years when chick and capelin timing matched. However, when capelin were late, despite increasing diving effort and DEE, parents delivered fewer fish to chicks per day and reduced breeding success was observed. While parents partially buffered the effects of variable capelin abundance by reducing co‐attendance time (time spent at the colony with mates) and increasing foraging time, physiological constraints on energy output likely limited their ability to maintain chick‐provisioning rates in a mismatch year. Such responses could have demographic consequences if ocean climate changes decouple the timing of chick‐rearing and prey availability.

Influenza A viruses infect a wide range of hosts, including many species of birds. Avian influenza A virus (AIV) infection appears to be most common in Anseriformes (ducks, geese, and swans) and some Charadriiformes (shorebirds and gulls), but many other birds also serve as hosts of AIV. Here, we evaluated the role of seabirds as hosts for AIV. We tested 3,160 swab samples from 13 seabird species between May 2008 and December 2011 in Newfoundland and Labrador, Canada. We also tested 156 serum samples for evidence of previous infection of AIV in Common Murres (Uria aalge) and Atlantic Puffins (Fratercula arctica). Avian influenza A virus was detected in breeding Common Murres and nonbreeding Thick-billed Murres (Uria lomvia), and Common Murres also had high antibody prevalence (44%). From these findings, combined with other studies showing AIV infection in murres, we conclude that murres are important for the ecology of AIV. For other species (Razorbill, Alca torda; Leach's Storm-Petrel, Oceanodroma leucorhoa; Black-legged Kittiwake, Rissa tridactyla; Atlantic Puffin) with good coverage (>100 samples) we did not detect AIV. However, serology indicates infection does occur in Atlantic Puffins, with 22% antibody prevalence found. The possibility of virus spread through dense breeding colonies and the long distance movements of these hosts make a more thorough evaluation of the role for seabirds as hosts of AIV important.

Examining factors that operate outside the breeding season may provide new insights into life-history traits such as egg size, in which individual variation has not been fully explained. We measured corticosterone (CORT) levels and δ 15 N values (trophic level) in feathers grown several months before egg-laying to test the prediction that a female's physiological state and feeding behaviour prior to the breeding season can influence egg mass in Atlantic Puffins Fratercula arctica . As predicted, egg mass increased with both CORT and δ 15 N values in feathers, suggesting that the ability of female Puffins to meet the nutritional costs of egg production is related to CORT promoting increased foraging effort during moult and to consumption of a higher trophic-level diet.

Corticosterone (CORT) levels in seabirds fluctuate across breeding stages and in different foraging conditions. Here we use a ten-year data set to examine whether CORT levels in Atlantic puffins differ in years with high or low availability of capelin, the preferred forage species. Female puffins had higher CORT levels than males, possibly related to cumulative costs of egg production and higher parental investment. Puffins had higher CORT levels and body mass during pre-breeding than during chick rearing. Yearly mean chick growth rates were higher in years when adults had higher body mass and in years where adults brought chicks a lower percentage of non-fish (invertebrates/larval fish) food. Unlike most results from seabird species with shorter chick-rearing periods, higher CORT levels in puffins were not associated with lower capelin abundance. Puffins may suppress CORT levels to conserve energy in case foraging conditions improve later in the prolonged chick-rearing period. Alternatively, CORT levels may be lowest both when food is very abundant (years not in our sample) or very scarce (e.g., 2009 in this study), and increase when extra foraging effort will increase foraging efficiency (most years in this study). If these data primarily represent years with medium to poor foraging, it is possible that CORT responses to variation in foraging conditions are similar for puffins and other seabirds.

In mammals, paternal care is rarer and more variable in its proximate mechanisms of development and underlying neural mechanisms than is maternal care. Here, we discuss how species differences in these proximate mechanisms reflect ecological pressures that have been selected for biparental care and argue that paternal care is more fixed (i.e., shaped less by social experiences) in those species where it is most important for infant survival. A second theme is that glucocorticoids such as cortisol and corticosterone are associated with both positive (more responsive to infant cues, more domestic work) and negative aspects of parenting (find parenting more difficult) in human fathers, findings that mirror research on maternal behavior. Finally, we discuss an animal model with obligatory biparental care, a seabird, the common murre (Uria aalge) - and show, as in humans, that elevated corticosterone is associated with both positive and negative aspects of parental responses, depending on environmental (foraging) context. We conclude that biparental care contributes to flexibility in reproductive strategies that allow organisms to extend their seasonal or geographic breeding ranges.Questions about parenting behavior can be examined from at least four different perspectives (as in Tinbergen, 1963). We share this view with Mileva and Fleming (see Chap. 1), based in part on the common training that Fleming and Storey received from the Institute of Animal Behavior and have shared with students and colleagues. These four perspectives include studies of mechanism and development at the individual level, which has been Fleming's focus, and studies of why and how the behavior evolved, which has been our emphasis. Studies of mechanism include all components discussed by Mileva and Fleming, including how sensory stimuli from the young initiate the hormonal and neural responses that trigger parental behavior. Mileva and Fleming's overview of the mechanisms underlying maternal behavior covered the field beautifully, summarizing the seminal contributions of Fleming and her colleagues. In fact, the work by Fleming and colleagues in this area is so comprehensive that there are no gaps.For this reason, we develop a comparison here with the much smaller literature on the other parent, the father. We are interested in evolutionary/functional questions such as why there are species and individual differences in fathers' involvement in the care of offspring. We explore how selection for flexibility in the expression of paternal care under different social and environmental conditions has shaped its development and neural mechanisms. In connection with fathers, we develop two other themes from the Mileva and Fleming chapter: the role of glucocorticoids (cortisol and corticosterone), hormones linked to both positive and negative aspects of parenting, and the use of an animal model to understand the ecological context in which biparental care evolves.

We tested first-time fathers with their 22-month old toddlers to determine whether social context variables such as pre-test absence from the child and presence of the mother affected physiological measures associated with paternal responsiveness. Heart rate and blood pressure readings as well as blood samples to determine prolactin, testosterone and cortisol levels were taken before and after the 30-min father–toddler interactions. Fathers were tested on a day when they were away from their child for several hours before testing (‘without-child’ day) and on another day where they remained with their child throughout the day (‘with-child’ day). Most measures decreased over the 30-min test period but relative decreases were context-dependent. Men maintained higher prolactin levels when they were away from their children longer before testing on the ‘without-child’ day. Cortisol levels decreased during both tests and they decreased more on the ‘with-child’ day for men who had spent more time alone with their toddler before the test. Heart-rate and diastolic (but not systolic) blood pressure decreased more on the ‘with-child’ day than on the ‘without-child’ day. Fathers' testosterone levels decreased when their partners were less involved in the interactions. Compared to men with high responsiveness ratings on both days, men whose responsiveness increased after being away from their child on the ‘without-child’ day maintained higher systolic blood pressure and had a greater decrease in testosterone levels. We conclude that context may be more important in determining fathers' physiological responses to child contact than has previously been appreciated, particularly for some individuals.

We investigated the role of egg lay order on growth and neural development in pre-fledgling European Starlings, Sturnus vulgaris. Chicks hatched from early-laid eggs had larger relative RA volumes than chicks hatched from later-laid eggs. There were no relationships between lay order and the volume of other brain regions, or chick growth metrics. In adult birds, RA volume is related to song repertoire size, and may affect mate attraction ability. Lay order effects on adult song nuclei should be examined further.