The role of parent–offspring interactions during and after fledging in the Black-legged Kittiwake

Most bird species endure a high mortality at fledging, and selection should favour parental behaviour diminishing these costs. Post-fledging parental care varies greatly among species and is often linked to parent–offspring recognition. In the Black-legged Kittiwake (Rissa tridactyla), fledglings need to return to the natal nest to be fed by their parents until independence. Rejections of fledglings by non-parent adults may be fairly violent, and parents are expected to recognize and help their chicks at the time of first return. However, previous cross-fostering experiments pointed out that parents are not able to recognize their chicks up to 15 days before fledging. In this paper, we study the behaviour of both parents and juveniles at fledging. We found that parents answered significantly more to their fledgling's calls than to those of others. Compared to silent juveniles, juveniles that called before landing were more likely to be accepted by their parents. No such pattern was observed with foreign juveniles, indicating that fledglings’ voice may carry individual identity. Furthermore, fledglings found their way back to the natal nest faster when parents attended the natal nest and reacted to their offspring's calls than when they were absent or inactive. Such interactions may therefore diminish juvenile mortality at fledging.     

Wild fledgling tits do not mob in response to conspecific or heterospecific mobbing calls

Mobbing, where birds harass a predator through a combination of vocalizations and stereotyped behaviours, is an effective anti-predator behaviour for many species. Mobbing may be particularly important for juveniles, as these individuals are often more vulnerable than adults. Although the component behaviours of mobbing are often considered to be un-learned, there are few confirmatory data, and the developmental trajectory of mobbing is unknown. In this study, we tested whether conspecific or heterospecific mobbing calls initiated mobbing behaviour in juvenile Blue Tits Cyanistes caeruleus. We located wild adult and recently fledged juvenile Blue Tits and presented them with playback recordings of adult conspecific (Blue Tit) and heterospecific (Great Tit Parus major) mobbing alarm calls. Although adult birds readily mob in response to these types of playbacks, juveniles did not exhibit characteristic mobbing behaviour. Some juveniles did, however, exhibit individual components of mobbing behaviour found in mobbing, despite not producing adult-like mobbing behaviour in response to either conspecific or heterospecific playback. These results suggest that, although birds might be capable of mobbing as juveniles, the associations between the non-vocal stereotyped mobbing behaviours and mobbing calls may be learned.     

Anti-predator defences of Argiope appensa (Araneae, Araneidae), a tropical orb-weaving spider

Anti-predator defence behaviour of Argiope appensa (Fuesslin) (Araneae, Araneidae) was studied in the laboratory. The most frequent response of adults and large juveniles of A. appensa to disturbance was pumping, a behaviour during which this web-building spider moved its body rapidly up and down with its legs remaining on the silk. When disturbed, small juveniles differed from adult females and larger juveniles by often dropping from the web instead of pumping. Argiope appensa sometimes put its web betweeen itself and stimuli from potential predators by shuttling from one side of the hub to the other. Argiope appensa occasionally tugged on the web but this behaviour appeared to be primarily a component of prey-catching sequences instead of defence. Experiments were carried out to determine the types of stimuli that elicited pumping. Lightly touching the spider or its web, forcefully hitting the web, and air movement elicited pumping but there was no evidence that chemical stimuli from potential predators were important.     

Age bias in the bag of pink-footed geese <Emphasis Type="Italic">Anser brachyrhynchus</Emphasis>: influence of flocking behaviour on vulnerability

In pink-footed goose (Anser brachyrhynchus) wintering in Denmark, The Netherlands and Belgium, the proportion of juveniles in the hunting bag is consistently higher than that observed in the autumn population. Such juvenile bias in the bag is usually ascribed to young geese lacking experience with hunting or disruption of juveniles from families. An alternative explanation may be that flocking behaviour of families make juveniles more vulnerable. Observations of morning flights of pink-footed geese to the feeding grounds from two of the major autumn-staging areas showed that geese were distributed in many small flocks (median flock size = 9). This was not significantly different from the flock size distribution shot at by hunters (median = 8), suggesting that hunters targeted goose flock size in proportion to the general probability of encounter. The rate at which hunters downed geese was independent of flock size. The ratio between juveniles and adults in flocks decreased with flock size and flocks of <60 individuals primarily comprised family groups. The likelihood of being shot at was 2.4 times higher for juveniles and 3.4 times higher for older birds in small flocks (<10 individuals) compared to larger flocks. The observations suggest that both juveniles as well as successful adult breeding birds were more vulnerable than non-breeding/failed breeding birds as a result of flocking behaviour.     

Juvenile Barn Swallows Hirundo rustica L. from late broods start autumn migration younger,fuel less effectively and show lower return rates than juveniles from early broods

Long‐distance migratory passerines may exhibit different post‐fledging rearing times between their early and late broods due to limited time and energy resources. This could affect the migratory fuelling behaviour, condition and fitness of juvenile birds. We analysed long‐term (13‐year) biometric data (body mass, fat score) on Barn Swallows ringed at the nest and later recaptured during their initial stages of autumn migration. The return rates of early‐ and late‐born juveniles after overwintering in Africa were further compared to estimate their fitness. We found that juveniles from late broods started migrating south on average 11 days younger compared with juveniles from early broods. Body masses of nestlings did not differ between early and late broods, but juveniles from late broods were in better condition after leaving the nest, possibly due to a longer period of parental care. Having started migration, juveniles from late broods were, however, less efficient in accumulating energy than juveniles from early broods. A younger departure age, together with less efficient fuelling of late brood juveniles, may partly explain the 39% lower return probability and hence lower fitness value of late‐brood juveniles. Our study is the first to show that juveniles from the early and late broods exhibit different fuelling behaviour and departure strategies (in terms of age and timing), which may be reflected in the fitness value of offspring.     

Seasonal variation in the metabolic rate and body composition of female grey seals: fat conservation prior to high-cost reproduction in a capital breeder?

Many animals rely on stored energy through periods of high energy demand or low energy availability or both. A variety of mechanisms may be employed to attain and conserve energy for such periods. Wild grey seals demonstrate seasonal patterns of energy storage and foraging behaviour that appear to maximize the allocation of energy to reproduction—a period characterized by both high energy demand and low food availability. We examined seasonal patterns in resting rates of oxygen consumption as a proxy for metabolic rate (RMR) and body composition in female grey seals (four adults and six juveniles), testing the hypothesis that adults would show seasonal changes in RMR related to the reproductive cycle but that juveniles would not. There was significant seasonal variation in rates of resting oxygen consumption of adult females, with rates being highest in the spring and declining through the summer months into autumn. This variation was not related to changes in water temperature. Adults increased in total body mass and in fat content during the same spring to autumn period that RMR declined. RMR of juveniles showed no clear seasonal patterns, but did increase with increasing mass. These data support the hypothesis that seasonal variation in RMR in female grey seals is related to the high costs of breeding.     

The trans‐equatorial loop migration system of Eleonora’s falcon: differences in migration patterns between age classes,regions and seasons

Internal factors such as experience (e.g. age) and motivation for breeding, and external ones such as environmental conditions (e.g. meteorology and landscape characteristics) can promote differences in migratory behaviour and routes among seasons, regions and populations. Using satellite telemetry we investigated whether such differences occur and which factors promote them among migrating Eleonora’s falcons breeding in the Mediterranean area (Spain and Croatia) and wintering in Madagascar. We found that during autumn migration no age differences occur when crossing the Sahara desert, but in the remaining African regions, juveniles were more prone than adults to fly at a slower and more tortuous rate, as well as exhibiting longer stop‐overs, particularly in the Sahel region. Such differences might be promoted by a lower foraging and pre‐migratory fattening efficiency in juveniles. During spring, routes were significantly more eastern than during autumn, resulting in a loop migration occurring in all studied populations. This could be accounted by seasonal variation in the distribution of trophic resources. Our results show that Eleonora’s falcons integrate spatially seasonal changing resources on a continental scale throughout their annual cycle, changing their movement patterns in response to internal (age) and external (habitat) factors. This loop migration pattern may prove to be widespread among other Palearctic trans‐continental migratory bird species.     

Aggressiveness is associated with genetic diversity in landlocked salmon (Salmo salar)

The amount of intraindividual genetic variation has often been found to have profound effects on life history traits. However, studies concerning the relationship between behaviour and genetic diversity are scarce. Aggressiveness is an important component of competitive ability in juvenile salmonids affecting their later performance and survival. In this study, we used an experimental approach to test the prediction that juveniles with low estimated genetic diversity should be less aggressive than juveniles with high estimated genetic diversity in fry from a highly endangered population of land-locked salmon (Salmo salar). This was achieved by using a method enabling the accurate estimation of offspring genetic diversity based on parental microsatellite genotype data. This allowed us to create two groups of offspring expected to have high or low genetic diversity in which aggressive behaviour could be compared. Salmon fry with low estimated genetic diversity were significantly less aggressive than fry with high estimated genetic diversity. Closer analysis of the data suggested that this difference was due to differences in more costly acts of aggression. Our result may reflect a direct effect of genetic variation on a fitness-related trait; however, we cannot rule out an alternative explanation of allele-specific phenotype matching, where lowered aggression is expressed towards genetically more similar individuals.     

Translocation for conservation: Neonates are less suitable than adults

Animal behaviour can affect the outcome of conservation translocations. It is important to understand the behaviour of the species being considered for translocation and how its behaviour varies over life stages. There may be uncertainty about what life stages are best as founders for release back into wild populations. A technique called head‐starting whereby juvenile life stages are raised in captivity and then released is one potential pre‐release strategy. However, juveniles of many species have a dispersive role in the life cycle, potentially raising difficulties for establishing new populations due to dispersal from the intended habitat following release. For this study, we compared aspects of the behaviour of captive adult and neonate pygmy bluetongue lizards (Tiliqua adelaidensis) – an endangered species for which translocation is likely to be an important management strategy – to determine if neonate behavioural characteristics are appropriate for their translocation. We filmed adult and neonate pygmy bluetongue lizards and compared their behaviour. We also filmed adults over an activity season to compare seasonal behaviour. Behavioural parameters measured included basking time, burrow exits, burrows occupied and walking the perimeter wall. Neonates basked significantly more than adults in summer and autumn. Neonates are likely to be basking more than adults because they are in a stage of rapid growth and need to gain body mass before the winter inactivity period. Neonates exited burrows more often than adults and used a greater number of burrows. These results indicate neonate lizards are actively exploring their habitat. Neonates are unlikely to be as suitable for translocation as they are actively moving about and more likely to be predated upon or disperse from the translocation site. Our finding can be applied to other species that have active juvenile life stages and are at particular risk of predation due to their small size.     

Scent-marking in free-ranging coyotes, Canis latrans

From November 1977 to March 1978 we recorded the scent-marking behaviour of free-ranging coyotes in southern Québec. Fourteen animals were marked by foot-pad ablation, which made it possible to recognize individuals' tracks in the snow and therefore to relate scent-marking with social organization. We observed 949 scent-marks. The identity of the animals was known for 50% of the tracking distances. Animals living in territorial groups (pairs and pairs with juveniles) marked more than twice as much as solitary non-territorial individuals. In addition the former used stronger forms of marking significantly more often than the latter.     

Initial winter flock formation in the Willow Tit Parus montanus. Do immigrating juveniles assess the quality of territorial adults?

In the Willow Tit Parus montanus , forming of winter flocks starts shortly after the juveniles have become independent of their parents. In the early phase of flock formation the juveniles roam about prospecting for suitable winter territories. They visit several occupied territories in succession and seek contact with the territory holders. I describe the behaviour of juveniles during such encounters with adult conspecifics. I suggest that, by approaching adults closely and behaving specifically, juveniles gain important information on the adults' innate qualities; this may affect the settling juveniles' future survival.     

Aggressive and neutral interventions in conflicts in captive groups of brown lemurs (Eulemur fulvus fulvus)

Third-party interventions in conflicts have revealed complexity in primate social relationships. This type of intervention has seldom been analyzed in prosimians, although many of these species exhibit complex (multimale/multifemale) social organizations. The present study on captive brown lemurs (Eulemur fulvus fulvus) shows that dominant individuals were more likely to intervene in conflicts. Both males and females intervened aggressively in conflicts. Female aggressive interventions occurred mainly on behalf of close kin, whereas males mainly intervened on behalf of juveniles. This study also provides the first record of neutral or peaceful interventions in lemurs. Although females intervened neutrally, almost all neutral interventions were by dominant males. Dominant males intervened in conflicts neutrally more often than aggressively, principally in conflicts between adults and juveniles or between juveniles. Neutral interventions by males always ended the conflicts and were often followed by affiliative contacts between participants (intervenors and opponents). In lemurs, female interventions can be explained by kin selection, while the nature of dominant males' interventions suggests a control role. Interventions by males on behalf of juveniles may increase the formers' fitness.     

Personality and Information Gathering in Free-Ranging Great Tits

One aspect of animal personality that has been well described in captivity, but received only little attention in studies in the wild, is that personality types may vary in their behavioural flexibility towards environmental changes. A fundamental factor underlying such differences is believed to be the degree to which individual behavior is guided by environmental stimuli. We tested this hypothesis in the wild using free-ranging great tits. Personality variation was quantified using exploratory behaviour in a novel environment, which has previously been shown to be repeatable and correlated with other behaviours in this and other populations of the same species. By temporarily removing food at feeding stations we examined whether birds with different personality differed in returning to visit empty feeders as this may provide information on how birds continue to sample their environment after a sudden change in conditions. In two summer experiments, we found that fast-exploring juveniles visited empty feeders less often compared to slow-exploring juveniles. In winter, sampling behaviour was sex dependent but not related to personality. In both seasons, we found that birds who sampled empty feeders more often were more likely to rediscover food after we again re-baited the feeding stations, but there was no effect of personality. Our results show that personality types may indeed differ in ways of collecting environmental information, which is consistent with the view of personalities as different styles of coping with environmental changes. The adaptive value of these alternative behavioural tactics, however, needs to be further explored.     

Inter-population variation in the behaviour of adult and juvenile Red-footed Boobies Sula sula

Early life is a critical phase of the life cycle of animals and is attracting increased attention because little information is available on the behaviour of young individuals during this period. Behaviour during early life is probably influenced by the environmental conditions encountered by young animals, but data on intraspecific variation between breeding sites during this crucial period of life are limited. Here we study variability in the foraging behaviour of juveniles and adults in three colonies of a pantropical seabird, the Red-footed Booby Sula sula. Both adults and juveniles were measured and fitted with GPS loggers in three remote islands: Genovesa (Galapagos, Eastern Pacific Ocean), Europa (Western Indian Ocean) and Surprise (New Caledonia, Western Pacific Ocean). Foraging behaviour was compared between age-classes, sex and colonies by examining trip characteristics, different behaviours at sea, potential associations between individuals and morphological characteristics. Compared with adults, juveniles conducted shorter trips that were restricted to around the colony, especially on Genovesa (max. range: 203.4 ± 125.1 km and 3.6 ± 3.1 km, respectively). Juveniles appeared more constrained by poor flight skills and experience rather than by their morphology. Adults travelled 45% of the time during at-sea trips, whereas juveniles spent a a lower proportion of time travelling but foraged more often using an ‘area-restricted search’ behaviour, potentially training to catch prey. Associations between juveniles were commonly detected in the three colonies and occurred mostly during foraging, suggesting that social learning is an important strategy. Variability of morphometric measurements in both adults and juveniles was high between sites, with larger birds found on Genovesa. These results suggest that adaptations to local environmental conditions are already visible in their early life. Future studies should continue to investigate the behavioural flexibility of juvenile birds to better understand the effect of local environmental conditions during this critical stage of life.     

‘One Can Always Say No.’ Enriching the Bioethical Debate on Antisocial Behaviour,Neurobiology and Prevention: Views of Juvenile Delinquents

Genomic and neuro‐scientific research into the causes and course of antisocial behaviour triggers bioethical debate. Often, these new developments are met with reservation, and possible drawbacks and negative side‐effects are pointed out. This article reflects on these scientific developments and the bioethical debate by means of an exploration of the perspectives of one important stakeholder group: juveniles convicted of a serious crime who stay in a juvenile justice institution. The views of juveniles are particularly interesting, as possible applications of current and future scientific findings are considered to be most effective if applied early in life. Based on their statements we come to the following provisional conclusions. Concerns about labelling and stigmatization are recognized and widely shared. Possible effects on one's identity are acknowledged too. Yet, a possible biological underpinning of one's antisocial behaviour is not considered to result in the development of a criminal identity. Nonetheless, psychopharmacological interventions are experienced as endangering one's current self. Concerns regarding the refusal of responsibility and the blaming of one's genes or brain can be put into perspective. Instead, participants emphasize the motive of own choice as underlying their criminal behaviour. Moreover, bioethical debate should pay attention to the role of parents of children at risk and the parent‐child relationship in families at‐risk. We argue that the short‐term and long‐term interests of children at risk, as well as their interests and those of society at large, may conflict. In order to deal appropriately with newly arising dilemmas, a normative framework needs to be developed.     

LIGHT, GRAVITY AND CONSPECIFICS AS CUES TO SITE SELECTION AND ATTACHMENT BEHAVIOUR OF JUVENILE AND ADULT DREISSENA POLYMORPHA PALLAS, 1771

Dreissena polymorpha, the zebra mussel, is one of the mostimportant components of the aquatic ecosystems it inhabits,due to high densities and filtration rates of this fouling organism.This laboratory study deals with several physical and biologicalfactors influencing zebra mussel juveniles (<10 mm) and adults(>10 mm) site selection behaviour and their byssal attachmentto substrate. Mussels preferred black substrate rather thanwhite. This preference was found to be stronger in smaller individuals.Furthermore, all mussels, independently of their size, selectedshadowed sites and avoided illuminated ones. Large mussels attachedmore often in darkness than in light, while for small specimenslight conditions made no difference. Large mussels tended toattach to lower parts of vertical test-tubes, while the numbersof small specimens in both halves of the test-tubes were similar.If initial conditions, used by mussels to select their attachmentsite, were changed by turning the test-tubes upside down, smallindividuals detached and looked for a new site more frequentlythan large ones. Large mussels attached more often in higherdensities of conspecifics, but physical contacts among conspecificsand their size composition seemed to have no impact on attachment.This study shows that many environmental stimuli influence locomotionand attachment of post-metamorphic zebra mussels. Therefore,the behaviour of this group may impact upon adult distributionobserved in field. Preferences exhibited by mussels lead tothe creation of dense aggregations in dark, deep places, providing protectionagainst dessication, predators and excessive water flow. (Received 18 April 2000; accepted 5 October 2000)     

Fight or flight: an investigation of aggressive behavior and predator avoidance in two populations of blue crabs (<Emphasis Type="Italic">Callinectes sapidus</Emphasis> Rathbun) in New Jersey

Recent literature has suggested aggression may be context dependent. The purpose of this investigation was to examine aggressive and predator avoidance behaviors in juvenile blue crabs of two populations. Furthermore, we wanted to determine whether aggression persisted into the adult stages. Juvenile blue crabs collected from an impacted estuary, the Hackensack Meadowlands (HM), were found to attack a threatening stimulus significantly more often (70%) than conspecifics from a less impacted estuary (Tuckerton—TK). TK juveniles responded significantly more often with a flight (~35%) or mixed response (~30%). Additionally, HM juveniles were significantly more successful than TK juveniles at avoiding an adult blue crab predator when sandy substrate was present in laboratory experiments. However, the video clarity made it impossible to determine which interactions were allowing survival. To determine if “aggression” exhibited by the HM juveniles was the reason for their enhanced survival, follow-up predator avoidance experiments were conducted without substrate and videotaped. The results of these experiments suggest that aggression per se is not the reason since aggressive juveniles were no more successful than non-aggressive individuals. The aggressive behavior exhibited by HM juveniles continues into the adult stages. This behavior may be important to recognize when estimating population size as well as local fishery efforts.     

Specificity and success of oral-bait delivery to Eurasian wild boar in Mediterranean woodland habitats

Eurasian wild boar (Sus scrofa) is an important reservoir host for pathogens affecting humans and domestic animals. The eradication of these diseases may require the development of control strategies that reduce pathogen transmission between wildlife and domestic animals. Baiting for oral vaccine delivery is often considered for wildlife disease control. The effective and efficient field vaccination of wildlife requires species-specific baits as delivery vehicles for oral vaccines and designing appropriate baiting strategies. The objective of this study was to determine the proportion of young and adult wild boar and non-target animals that consumed baits containing a chemical marker, iophenoxic acid (IPA), in delivery trials conducted in summer in four different sites in the Mediterranean region of Spain where wild boar are abundant. The proportion of wild boar showing IPA markers in serum in autumn ranged from 11.5% to 56.4%. When attending to age classes, 12.6% to 72.7% of young individuals presented IPA. The results evidenced that the percent of wild boar that ingested the baits varied among study sites and age classes. Placing baits inside selective cages (for juveniles) and under heavy pavel stones (for adults) contributed to improve age specificity in bait consumption. We suggest ways for improving the age specificity of bait delivery systems used for young and adult wild boar.     

Functions and consequences of play behaviour in juvenile Belding's ground squirrels

We evaluated hypotheses suggesting that play behaviour in free-living juvenile Belding's ground squirrels, Spermophilus beldingi, helps to regulate energy balance and promotes development of motor skills. We also examined the possibility that play behaviour and motor development influence important early life events in S. beldingi. We regularly measured body fat of juveniles using nondestructive methods, observed their behaviour, conducted motor skills tests, monitored dispersal status of males, and evaluated weaning success of females during their first effort to reproduce as yearlings. Rates of feeding were greater among juveniles who engaged in both social and nonsocial play behaviour at low compared to high rates, suggesting that play does not help young animals expend excess energy that they consume. By contrast, body fat was greater among juveniles who engaged in social play at high compared to low rates, supporting the idea that energetic variables such as body fat limit the expression of play behaviour. Motor skills of juvenile S. beldingi improved throughout the period in which juveniles engaged in play behaviour. Improvement in motor skills was greater in juveniles who engaged in social play at high compared to low rates, suggesting a link between social play and motor development. Motor skill levels at the end of the play period were greater among males who dispersed by the end of the juvenile summer than among males still residing in their natal areas. Rates of social play and improvement in motor skills over the course of the play period were greater in females who successfully weaned a litter as yearling than in females who did not. These last two results raise the possibility that play behaviour and motor development during the play period influence important events in the early lives of S. beldingi, which may ultimately influence long-term reproductive success.     

Diurnal and seasonal behaviour of adult and juvenile European catfish as determined by radio-telemetry in the River Berounka, Czech Republic

The first telemetry study analysing behaviour of the largest freshwater predator in European rivers, Silurus glanis , was performed bimonthly during the years 2002–2004. Movement of juveniles and adults occurred mostly in the same time intervals. The only statistical differences occurred for nocturnal activity in spring and autumn. In spring and winter, activity was low with the peaks during daylight, and in autumn, maximal movement was recorded during dusk. In summer, the European catfish were active across the whole 24 h even during high-flow conditions. During all other seasons, movement was inversely related to flow rate. Maximal home ranges occurred in summer, being larger for adults. Juveniles and adults were spatially segregated. With increasing flow, fish were displaced, and individuals from both groups got closer to each other. Only juveniles migrated downstream from the upstream isolated river stretch suggesting a negative impact of lateral obstructions on the fish population structure.