Behavior of crested auklets (<Emphasis Type="Italic">Aethia cristatella</Emphasis>, Charadriiformes,Alcidae) in the breeding season: Visual and acoustic displays

The crested auklet, a highly social planktivorous bird species of the Northern Pacific, is an important component of marine ecosystems. Although visual and acoustic modalities play a major role in the communication of these birds, the available data on the repertoire of their vocal signals and postures are scarce and lack quantitative analysis. This study deals with visual and acoustic displays of crested auklets on their breeding grounds and the occurrence frequencies of certain forms of social behavior in male and female birds. The data were collected on Talan Island (the Sea of Okhotsk) in 1987–1991 and 2008. They show that the rate of contacts between birds is very high and sex-specific: on average, males initiate 1.13 contacts/min, compared to 0.65 contacts/min initiated by females. Directionality of ruff-sniff displays differs depending on the posture of the recipient bird. The duration of the trumpeting display in males depends on their social surroundings. However, the duration of either the trumpeting display or the mutual cackling display during courtship is independent of the behavioral context. Vocalization of crested auklets is characterized by two independent basic frequencies occurring either sequentially or simultaneously. The role of different communicative modalities in the behavior of the crested auklet is discussed.     

Is the citrus-like plumage odorant of crested auklets (Aethia cristatella) a defense against lice?

Plumage odors may function as chemical defenses against ectoparasites in birds. We tested this hypothesis for crested auklets (Aethia cristatella), a species of colonial seabird that emits a very strong citrus-like odor from its plumage. This odorant contains known chemical repellents. We evaluated evidence for chemical defense in this species using two approaches. First, we exposed pigeon lice to the volatiles emitted by freshly plucked plumage and by whole specimens. Louse survivorship was compared between these treatments and two controls. Second, we compared louse abundance on crested auklets versus a closely related congener that nests in close association. Louse survivorship did not differ between crested auklet treatments and controls. Comparison of ectoparasite loads showed that crested auklets had significantly higher louse abundance than least auklets (A. pusilla), even after controlling for body size. Our results failed to support two expectations for chemical defense. Presence of the crested auklet plumage odorant in our experiments did not reduce louse life span. Presence of the aldehyde odorant in nature did not reduce louse abundance on crested auklets. Hence we conclude that the aldehyde odorant is not immediately lethal to lice at natural concentrations in plumage.     

Inter- and intra-season stability of vocal individual signatures in a social seabird, the crested auklet

Vocal plasticity due to changes of social context is well documented in passerine birds. In other bird species, the impact of social environment changes on the whole vocal structure and on individual specific signatures remains largely unexplored. Here, we assessed inter- and intra-season stability of specific features of individual signatures in advertising calls of crested auklet (Aethia cristatella) males and tested the effects of pair mate and territory changes on the stability of the calls. The crested auklet is a highly social seabird of the North Pacific that breeds in dense colonies, and its individuals switch pair mates and territories with probability of 25–54%. During summer 2008–2010, we recorded 464 trumpet calls from 21 individually marked males and determined their pair mates and positions of their displaying places on a breeding colony of Talan Island, Sea of Okhotsk. We found that strong individual specific features of crested auklet trumpet calls stay stable not only during one season but also from year to year. However, we failed to find any effects of pair mate or territory changes on individual signatures of crested auklet trumpet calls. Our results suggest that crested auklets can potentially use their individually specific trumpet calls to form long-term social bonds both between pair mates and between neighbors; however, future experimental studies should test whether this is indeed the case.     

Heterospecific mating preferences for a feather ornament in least auklets

Auklets (Alddae, Aethiini) include five species of small, sociallymonogamous, sexually monomorphic seabirds that display a varietyof feather and bare-part ornaments during the breeding season.Previous experimental work on two auklet species has demonstratedthat some ornaments are likely to be favored by sexual selectionbecause mutual male and female mating preferences benefit individualswith the most elaborate expression of these traits. In thisstudy we experimentally investigated whether naturally crestlessleast auklets Aethia pusilla have a maring preference for foreheadcrests similar to the most prominent ornament of two other species,crested A. cristatella and whiskered auklets A. pygmaea. Ourobjective was to investigate the function of this ornament asa species-recognition mechanism or as a product of one or moreof three proposed sexual selection models that address the originof elaborate traits and preferences. During the experiment,least auklets reacted to realistic models equipped with artificialforehead crests with approximately an order of magnitude morefrequent sexual displays and greater interest, consistent withthe idea that they have a mating preference for crests, eventhough they do not naturally express this ornament This heterospecificpreference also favored large crest size. These results refutethe possibility that least auklet forehead ornamentation alonedetermines species recognition at present Among models of sexualselection considered, the results are consistent with the sensoryexploitation model, although this could not be established unequivocallybecause a viability indicator or Fisherian mechanism could havebeen involved if least auklets had an ancestor with a foreheadcrest.     

Size of ornament is negatively correlated with baseline corticosterone in males of a socially monogamous colonial seabird

The Goymann–Wingfield model predicts that glucocorticoid levels in social animals reflect the costs of acquiring and maintaining social status. The crested auklet is one of the few avian colonial species where a mutual ornament in males and females is used in both sexual and aggressive displays. Previous studies of the crested auklet support the notion that the crest ornament is a badge of status in this species. Here, we examined the relationship between the crest ornament size and the adrenocortical function in breeding crested auklets. Crest length was negatively correlated with corticosterone at baseline in males, but not in females. Baseline corticosterone in females (but not in males) was negatively correlated with body condition index. Although male and female crested auklets are monomorphic in their ornamental traits, our results suggest that the socially mediated physiological costs associated with status signaling may differ between the sexes.     

Responses of Snow Voles, Chionomys nivalis, Towards Conspecific Cues Reflect Social Organization during Overwintering Periods

Among microtine rodents, reaction to chemical cues from conspecifics is assumed to reflect social and spatial relationships. Generally, strong attraction of particular odours correlates with non‐aggressive behaviour and high spatial tolerance towards odour donors, whereas weak attraction correlates with greater levels of aggression and spatial segregation. In the present study, we examined whether winter odour preferences of the snow vole Chionomys nivalis, a rock‐dwelling microtine principally found at high‐mountainous regions, differ from that of other vole species, owing to their different social organization during overwintering periods. The social structure of C. nivalis over the winter period is relatively unusual among vole species in that they become nomadic and solitary. In odour choice trials under laboratory conditions, we found that both males and females avoided zones with conspecific odours of both sexes in comparison with unscented control zones or own odours. These results are consistent with the elevated levels of intraspecific aggression and spatial isolation of C. nivalis during overwintering periods. Furthermore, scent‐elicited self‐grooming increased when their own odour was offered against conspecific cues. This, in combination with an active avoidance of conspecific odours, might functionally contribute to minimize direct confrontations between solitary individuals, thereby reducing the risks of aggressive encounters during overwintering periods.     

Individual recognition in salamanders: Cloacal odours

Male red-backed salamanders (Plethodon cinereus) were studied to determine the origin of the chemical cues allowing for individual odour recognition between conspecifics. Individual males showed a preference for substrates with their own faecal and cloacal odours rather than those marked by unfamiliar conspecific males. This discriminatory ability did not depend on recent differences in food consumed. These scent marks might be used to define breeding territories in the field.     

Olfactory Sex Recognition Investigated in Antarctic Prions

Chemical signals can yield information about an animal such as its identity, social status or sex. Such signals have rarely been considered in birds, but recent results have shown that chemical signals are actually used by different bird species to find food and to recognize their home and nest. This is particularly true in petrels whose olfactory anatomy is among the most developed in birds. Recently, we have demonstrated that Antarctic prions, Pachyptila desolata, are also able to recognize and follow the odour of their partner in a Y-maze.However, the experimental protocol left unclear whether this choice reflected an olfactory recognition of a particular individual (i.e. partner) or a more general sex recognition mechanism. To test this second hypothesis, male and female birds'' odours were presented simultaneously to 54 Antarctic prions in a Y-maze. Results showed random behaviour by the tested bird, independent of its sex or reproductive status. Present results do not support the possibility that Antarctic prions can distinguish the sex of a conspecific through its odour but indirectly support the hypothesis that they can distinguish individual odours.     

The effects of sex, reproductive condition and context on discrimination of conspecific odours by giant pandas

To elucidate some of the functions of chemical communication in giant pandas, Ailuropoda melanoleuca, we systematically exposed captive males, oestrous and nonoestrous females to each others' odours by providing access to one another's temporarily unoccupied enclosures. In comparison with control observations, pandas from all reproductive categories displayed a dramatic increase in several measures of chemosensory responsiveness, both when visiting another panda's enclosure and when encountering scent deposited in their home enclosure. Evidence for discrimination between odours encountered as a resident versus a visitor was minimal, but male pandas' response patterns were suggestive of a territorial function. We also found evidence for discrimination of sex and reproductive condition via chemical cues. Males showed a marked preference for female odours, investigating, licking, scent marking and vocalizing more in response to female than male odours. Males also vocalized more in response to oestrous than nonoestrous female odours. Nonoestrous females licked more and oestrous females vocalized more when encountering male than female odours. Our data on vocalizations suggest a potential role for odours in the activation of sexual motivation. We argue that the low reproductive success observed in captivity may be attributed in part to failure to provide sufficient opportunities for chemical communication, and encourage the judicious management of social odours to promote natural mating (e.g. using intersexual odour exposure to increase libido and decrease aggressiveness prior to mating introductions). Copyright 2000 The Association for the Study of Animal Behaviour.     

Discrimination of individual odours by hamsters (Mesocricetus auratus) varies with the location of those odours

When animals perceive social signals, information about the identity and the location of the signaller can be important determinants of a response by the perceiver. An unfamiliar individual often elicits a greater response than does a familiar individual. Similarly, a signal from an unexpected location may elicit a greater response than if it came from an expected location. For example, in field experiments on vocal communication in birds, an unexpected location has been many metres away from the expected one. Laboratory experiments on the responses of voles and hamsters to scent overmarks and on the habituation of hamsters to social scents suggest that much smaller differences in the location of odours may be salient. To explore this further, we examined the influence of changes in spatial location of familiar and novel male scents on responses of female golden hamsters,M. auratus . The spatial changes were about 9 cm, less than three-fourths of the body length of our subjects. The decline in females' investigation of the same male's flank odour across four habituation trials was not affected by changing the location of the odour. During test trials, however, changes in location did influence the results. The expected higher level of investigation of a novel scent versus that of a familiar one was observed primarily when the novel scent occupied a novel location. Such increases in investigation were usually not seen when only one of these variables was changed (individual or location). Thus, small changes in spatial location influence the salience of conspecific odours in this species. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Vocal and Optical Indicators of Individual Quality in a Social Seabird,the Crested Auklet (Aethia cristatella)

Indicators of individual quality in ornamentation or in vocalizations have been reported for different animal species. However, no studies have jointly investigated ornamentation and vocalizations in one species. The crested auklet (Aethia cristatella, Alcidae) is a small colonial seabird of the North Pacific and is unusual for a bird in using optical, vocal, and olfactory signals. We estimated the potential for coding individual quality in vocalizations and plumage ornamentation and the relationship between vocal and optical traits in crested auklets. During the summer seasons of 2008–2009, we recorded 359 trumpet calls from 28 individually marked males and measured indices of body size, condition, and plumage patterns of 58 male and 48 female crested auklets from a breeding colony on Talan Island, Sea of Okhotsk. We found strong interindividual differences in trumpet call characteristics. Furthermore, we found that the maximum fundamental frequency of the loudest notes of the trumpet call is negatively correlated with body condition, and head crest length is positively correlated with body size. However, we found no relationship between vocal and ornamental traits. The results suggest that advertising calls of crested auklets signal caller individuality and quality, but future experimental studies should test whether or not this is indeed case.     

Are olfactory cues involved in nest recognition in two social species of estrildid finches?

Reliably recognizing their own nest provides parents with a necessary skill to invest time and resources efficiently in raising their offspring and thereby maximising their own reproductive success. Studies investigating nest recognition in adult birds have focused mainly on visual cues of the nest or the nest site and acoustic cues of the nestlings. To determine whether adult songbirds also use olfaction for nest recognition, we investigated the use of olfactory nest cues for two estrildid finch species, zebra finches (Taeniopygia guttata) and Bengalese finches (Lonchura striata var. domestica) during the nestling and fledgling phase of their offspring. We found similar behavioural responses to nest odours in both songbird species. Females preferred the odour of their own nest over a control and avoided the foreign conspecific nest scent over a control during the nestling phase of their offspring, but when given the own odour and the foreign conspecific odour simultaneously we did not find a preference for the own nest odour. Males of both species did not show any preferences at all. The behavioural reaction to any nest odour decreased after fledging of the offspring. Our results show that only females show a behavioural response to olfactory nest cues, indicating that the use of olfactory cues for nest recognition seems to be sex-specific and dependent on the developmental stage of the offspring. Although estrildid finches are known to use visual and acoustic cues for nest recognition, the similar behavioural pattern of both species indicates that at least females gain additional information by olfactory nest cues during the nestling phase of their offspring. Thus olfactory cues might be important in general, even in situations in which visual and acoustic cues are known to be sufficient.     

Breeding Biology of the Whiskered Auklet (Aethia pygmaea): Postnesting Period

This is the third paper on the breeding biology of the whiskered auklet on Buldyr' Island (Aleutian Islands) based on material collected in 1993. Unlike other alcid birds, both adult and young whiskered auklets returned to the colony the night after the end of the breeding season. From the end of July until the third ten-day period of August, the number of adult birds that returned to the island was at approximately the same level, and then decreased, while the number of young birds that returned to the islands markedly varied, and peaks were noted every 5–8 nights. Adult birds continued to visit all the nest habitats, but not all nest chambers were visited equally frequently. In the first and third ten-day periods of August, the auklets visited 61% and 19.8% of the nest chambers, respectively. It remains unclear whether they were their hosts, or other birds used their nests for the next year. The return of adult and young birds to the colony to sleep after the breeding season appears to be related to the settled mode of life of the whiskered auklet and its feeding near the islands in water perturbations caused by tidal currents.     

Molting and Seasonal Bill-Plate Shedding in the Whiskered Auklet (Aethia pygmaea)

Feather molting and bill-late shedding were studied because of the unique features of the whiskered auklet biology; i.e., they continue to visit the colony after departure of their young. Like other auklets, the whiskered auklets begin to molt during breeding and do not lose their capacity for flight. The molt pattern of different wing feathers is adaptive and allows new feathers to be protected (when they are soft and could be easily injured) by old or full-grown new feathers during flight or feeding (diving) due to the different timing of the molt of primary feathers and their coverts. The possibility of combining breeding with molt appears to be related to the feeding features of the species. The species that feed on abundant and highly aggregated plankton are able to molt during breeding. The pattern of bill-plate shedding in the whiskered auklet is similar to that in the crested auklet.     

Chemical kin label in seabirds

Chemical signals yield critical socio-ecological information in many animals, such as species, identity, social status or sex, but have been poorly investigated in birds. Recent results showed that chemical signals are used to recognize their nest and partner by some petrel seabirds whose olfactory anatomy is well developed and which possess a life-history propitious to olfactory-mediated behaviours. Here, we investigate whether blue petrels (Halobaena caerulea) produce some chemical labels potentially involved in kin recognition and inbreeding avoidance. To overcome methodological constraints of chemical analysis and field behavioural experiments, we used an indirect behavioural approach, based on mice olfactory abilities in discriminating odours. We showed that mice (i) can detect odour differences between individual petrels, (ii) perceive a high odour similarity between a chick and its parents, and (iii) perceive this similarity only before fledging but not during the nestling developmental stage. Our results confirm the existence of an individual olfactory signature in blue petrels and show for the first time, to our knowledge, that birds may exhibit an olfactory kin label, which may have strong implications for inbreeding avoidance.     

Individuality in trumpet calls of the crested auklet (<Emphasis Type="Italic">Aethia cristatella</Emphasis>), a highly social species

Crested auklet is a unique representative of the family Alcidae with a complex social behavior nesting in dense colonies with a size of up to one million individuals. Here we study specific individual features in their trumpet calls, loud vocalizations used by auklets as an advertising display. In 2008 and 2009, we recorded 231 calls of 24 individually marked male crested auklets from the Talan Island (Sea of Okhotsk). According to a stepwise discriminant function analysis based on seven variables in the call introduction, the rate of correct call assignment to an individual was 84.8% and that in the case of seven variables of the main part of the call was 82.3%, which considerably exceeds a random classification. Thus, a single introduction or a single main part of the call is sufficient for a reliable individual identification of a calling bird. We assume that such redundancy of information for individual recognition can enhance identification of calls of a large number of auklet conspecifics in dense colonies with a nesting density of several tens of pairs per 1 m².     

Pheromonal Recognition of Females Takes Precedence over the Chromatic Cue in Male Iberian Wall Lizards Podarcis hispanica

Sex recognition is based on colour signals in many species of lizards. However, olfactory stimuli are also clearly involved, and many species might rely more on chemoreception. We aimed to examine whether colour pattern or odours, or both, are used in sex recognition and which cues elicit courtship of females by males of the lizard Podarcis hispanica . We experimentally manipulated the coloration and odour of female P. hispanica , thereby creating groups with all combinations between coloration and odour of males and females. Using data from staged encounters, we compared the responses of resident males to manipulated and unmanipulated individuals (males and females). Responding males reacted significantly more aggressively to female intruders with male odours, independently of their coloration. Nevertheless, coloration seemed to be important in long-distance sex recognition since, in the first minutes, females painted as females received a lower number of aggressive responses. Both colour and odour were important in eliciting male courtship. However, females painted as females and with female odours were preferentially courted. Comparisons with unmanipulated male and female intruders agreed with these expectations. Therefore, at close range, odoriferous cues seem to be more important than colour patterns in sex recognition, but female coloration is also useful at long range to deter the aggressive response of males and to elicit courtship in conjunction with odours.     

The response to the social environment reveals sex-dependent behavioural syndromes in the Bosca’s newt (<Emphasis Type="Italic">Lissotriton boscai</Emphasis>)

There is growing evidence of correlated behaviours across time, situations and/or contexts (behavioural syndromes) in animals, and their link with fitness makes these studies mandatory to understanding the species’ behavioural and evolutionary ecology. Whereas the role of the social environment on behavioural syndromes is receiving increasing attention, experimental studies testing whether environmental fluctuations govern sex-dependent behavioural syndromes are scarce. I performed an experiment to test for the existence of sex differences in activity syndromes through a changing social environment. Males and females of Bosca’s newt (Lissotriton boscai) were faced with three social situations perceived through chemical cues (own odour, no odour and same-sex conspecific odours) to measure their activity levels. Comparisons of the activity levels showed that both males and females discriminated the odourless stimuli from newt odour (either their own or the conspecific stimuli). Whereas activity levels were positively correlated between their own and the odourless stimuli in both sexes, the association between the odourless and conspecific stimuli was positive in males but decoupled in females. This is the first experimental evidence of sex differences in activity syndromes of wild-caught animals in response to social changes.     

Seasonal covariation in progesterone and odorant emissions among breeding crested auklets (Aethia cristatella)

Crested auklets emit a citrus-like odorant that is seasonally modulated, suggesting that it is a secondary sexual trait. We hypothesized that expression of the chemical odorant is facilitated by steroid hormones, similar other secondary sexual traits in birds. Therefore we examined variation in concentrations of hormones in blood plasma and odor production during incubation and early chick rearing. A novel method was used to obtain and measure chemical emissions of crested auklets. Blood plasma samples were analyzed by radioimmunoassay. Progesterone was detected in all birds, and it varied during the breeding season. Octanal emissions covaried with progesterone levels in males but not in females. No seasonal patterns were detected in testosterone, estrogen or DHT, and these hormones were not detected in all breeding adults. Covariance of progesterone and octanal emissions in males suggests there could be at least an indirect relationship between odor emissions and steroid hormones in this species. Thus expression of the citrus-like odorant of crested auklets, like other secondary sexual traits in birds, could be regulated by steroid hormones.     

Round goby Neogobius melanostomus attraction to conspecific and heterospecific egg odours

In this study, cannibalistic and predatory responses of juvenile Neogobius melanostomus (either fed or deprived of food and caught during the reproductive summer or non-reproductive winter season) to water washings of fertilized eggs from conspecifics (N. melanostomus), heterospecifics (rainbow trout Oncorhynchus mykiss) and control lake water were tested. Fed juveniles (summer season) spent significantly more time on the side of the flume containing stimuli from conspecific eggs over control water, while significantly preferring control water to heterospecific stimuli. In addition, fish showed a significant preference towards stimuli from conspecific eggs over heterospecific stimuli by associating near conspecific egg odours 1·5 times longer [Correction added after online publication 28 April 2011, text changed]. Fish that were deprived of food, regardless of whether caught during the summer or winter season, did not show any preference towards either conspecific or heterospecific stimuli. These findings show that conspecific egg odours attract fed juveniles and that there is a potential to lure fish to odour traps as a means of control.