Shy Birds Research Articles

Personality-specific carry-over effects on breeding.

Carry-over effects describe the phenomenon whereby an animal's previous conditions influence its subsequent performance. Carry-over effects are unlikely to affect individuals uniformly, but the factors modulating their strength are poorly known. Variation in the strength of carry-over effects may reflect individual differences in pace-of-life: slow-paced, shyly behaved individuals are thought to favour an allocation to self-maintenance over current reproduction, compared to their fast-paced, boldly behaved conspecifics (the pace-of-life syndrome hypothesis). Therefore, detectable carry-over effects on breeding should be weaker in bolder individuals, as they should maintain an allocation to reproduction irrespective of previous conditions, while shy individuals should experience stronger carry-over effects. We tested this prediction in black-legged kittiwakes breeding in Svalbard. Using miniature biologging devices, we measured non-breeding activity of kittiwakes and monitored their subsequent breeding performance. We report a number of negative carry-over effects of non-breeding activity on breeding, which were generally stronger in shyer individuals: more active winters were followed by later breeding phenology and poorer breeding performance in shy birds, but these effects were weaker or undetected in bolder individuals. Our study quantifies individual variability in the strength of carry-over effects on breeding and provides a mechanism explaining widespread differences in individual reproductive success.

Personality influences foraging of a seabird under contrasting environmental conditions

Personality is relevant in shaping the way animals respond to environmental conditions. Some personality traits may be disadvantageous under non-optimal environmental conditions, reducing foraging success and breeding performance in the long term. In this study we tested whether individual personality plays a role in determining shifts in seabirds' foraging behaviour and habitat use when environmental conditions are poor. We used GPS-tracking information from chick-rearing Cory's Shearwaters (Calonectris borealis) during eight consecutive years. Boldness was measured by the response of the tracked individuals to a novel object presented at their nest. Foraging habitat was identified as the environment within geographic points where birds were flying at low speed with high turning rates. We found that bold individuals displayed more foraging habitat consistency and boldness influenced foraging habitat during years of poor environmental conditions. Bold individuals tended to remain closer to the colony under poor environmental conditions, while shy individuals dispersed considerably farther from the colony. However, there was no influence of the personality on breeding success, and the whole population tended to have a lower probability of breeding success during years of poor conditions. During adverse environmental conditions, shy birds shifted habitat, probably as consequence of exploitative competition with the bold birds, but this has no effect on the birds' ability to successfully raise a chick.

Personality and the collective: bold homing pigeons occupy higher leadership ranks in flocks.

While collective movement is ecologically widespread and conveys numerous benefits on individuals, it also poses a coordination problem: who controls the group's movements? The role that animal 'personalities' play in this question has recently become a focus of research interest. Although many animal groups have distributed leadership (i.e. multiple individuals influence collective decisions), studies linking personality and leadership have focused predominantly on the group's single most influential individual. In this study, we investigate the relationship between personality and the influence of multiple leaders on collective movement using homing pigeons, Columba livia, a species known to display complex multilevel leadership hierarchies during flock flights. Our results show that more exploratory (i.e. 'bold') birds are more likely to occupy higher ranks in the leadership hierarchy and thus have more influence on the direction of collective movement than less exploratory (i.e. 'shy') birds during both free flights around their lofts and homing flights from a distant site. Our data also show that bold pigeons fly faster than shy birds during solo flights. We discuss our results in light of theories about the evolution of personality, with specific reference to the adaptive value of heterogeneity in animal groups.This article is part of the theme issue 'Collective movement ecology'.

Novelty induces behavioural and glucocorticoid responses in a songbird artificially selected for divergent personalities

Stress physiology is thought to contribute to individual differences in behaviour. In part this reflects the fact that canonical personality measures consist of responses to challenges, including novel objects and environments. Exposure to novelty is typically assumed to induce a moderate increase in glucocorticoids (CORT), although this has rarely been tested. We tested this assumption using great tits, Parus major, selected for divergent personalities (bold-fast and shy-slow explorers), predicting that the shy birds would exhibit higher CORT following exposure to a novel object. We also scored behavioural responses to the novel object, predicting that bold birds would more frequently approach the novel object and exhibit more abnormal repetitive behaviours. We found that the presence of a novel object did induce a moderate CORT response, but selection lines did not differ in the magnitude of this response. Furthermore, although both selection lines showed a robust CORT elevation to a subsequent restraint stressor, the CORT response was stronger in bold birds and this effect was specific to novel object exposure. Shy birds showed a strong positive phenotypic correlation between CORT concentrations following the novel object exposure and the subsequent restraint stress. Behaviourally, the selection lines differed in their response during novel object exposure: as predicted, bold birds more frequently approached the novel object and shy birds more strongly decreased overall locomotion during the novel object trial, but birds from both selection lines showed significant and similar frequencies of abnormal repetitive behaviours during novel object exposure. Our findings support the hypothesis that personality emerges as a result of correlated selection on behaviour and underlying endocrine mechanisms and suggest that the relationship between endocrine stress physiology and personality is context dependent.

Boldness predicts an individual's position along an exploration-exploitation foraging trade-off.

Individuals do not have complete information about the environment and therefore they face a trade‐off between gathering information (exploration) and gathering resources (exploitation). Studies have shown individual differences in components of this trade‐off but how stable these strategies are in a population and the intrinsic drivers of these differences is not well understood.Top marine predators are expected to experience a particularly strong trade‐off as many species have large foraging ranges and their prey often have a patchy distribution. This environment leads these species to exhibit pronounced exploration and exploitation phases but differences between individuals are poorly resolved. Personality differences are known to be important in foraging behaviour but also in the trade‐off between exploration and exploitation. Here we test whether personality predicts an individual exploration–exploitation strategy using wide ranging wandering albatrosses (Diomedea exulans) as a model system.Using GPS tracking data from 276 wandering albatrosses, we extract foraging parameters indicative of exploration (searching) and exploitation (foraging) and show that foraging effort, time in patch and size of patch are strongly correlated, demonstrating these are indicative of an exploration–exploitation (EE) strategy. Furthermore, we show these are consistent within individuals and appear stable in the population, with no reproductive advantage.The searching and foraging behaviour of bolder birds placed them towards the exploration end of the trade‐off, whereas shy birds showed greater exploitation. This result provides a mechanism through which individual foraging strategies may emerge. Age and sex affected components of the trade‐off, but not the trade‐off itself, suggesting these factors may drive behavioural compensation to maintain resource acquisition and this was supported by the evidence that there were no fitness consequence of any EE trait nor the trade‐off itself.These results demonstrate a clear trade‐off between information gathering and exploitation of prey patches, and reveals for the first time that boldness may drive these differences. This provides a mechanism through which widely reported links between personality and foraging may emerge.

Shy birds play it safe: personality in captivity predicts risk responsiveness during reproduction in the wild.

Despite a growing body of evidence linking personality to life-history variation and fitness, the behavioural mechanisms underlying these relationships remain poorly understood. One mechanism thought to play a key role is how individuals respond to risk. Relatively reactive and proactive (or shy and bold) personality types are expected to differ in how they manage the inherent trade-off between productivity and survival, with bold individuals being more risk-prone with lower survival probability, and shy individuals adopting a more risk-averse strategy. In the great tit (Parus major), the shy-bold personality axis has been well characterized in captivity and linked to fitness. Here, we tested whether 'exploration behaviour', a captive assay of the shy-bold axis, can predict risk responsiveness during reproduction in wild great tits. Relatively slow-exploring (shy) females took longer than fast-exploring (bold) birds to resume incubation after a novel object, representing an unknown threat, was attached to their nest-box, with some shy individuals not returning within the 40 min trial period. Risk responsiveness was consistent within individuals over days. These findings provide rare, field-based experimental evidence that shy individuals prioritize survival over reproductive investment, supporting the hypothesis that personality reflects life-history variation through links with risk responsiveness.

Dominance, pair bonds and boldness determine social-foraging tactics in rooks, Corvus frugilegus

Socially foraging animals can search for resources themselves (produce) or exploit the discoveries made by others (scrounge). The extensive literature on producerescrounger dynamics has mainly focused on scramble competition over readily accessible resources, thereby largely neglecting the variety of scrounging techniques individuals may use as well as the role of investment in food handling. Furthermore, although individual differences in boldness and social factors such as dominance have been described to influence foraging tactics, their potential interplay and effect in foraging contexts beyond the conventional producerescrounger game remains unclear. We investigated the relationship between social-foraging tactic use and dominance, pair bonds and boldness in a foraging experiment focused on food handling and alternative scrounging tactics. We conducted a producerescrounger experiment in a captive group of rooks in which individuals could produce by pulling up baited strings, or scrounge by retrieving fallen food items or joining a producer. There were three key findings: (1) dominant rooks adopted the producer tactic more often and more successfully than subordinates; (2) producing and scrounging by tolerance led to mixed benefits to paired birds; (3) bold birds scrounged by retrieving more often than shy birds. Importantly, individuals were highly consistent in their tactic use across conditions differing in food availability. Our study highlights the importance of taking both social factors and boldness (heterogeneity) into account when studying social-foraging dynamics and offers empirical data on food handling and alternative scrounging tactics that can be used to extend current models and experiments on social foraging.

Sonnet On a November Day

nearly seventy dollars like that once, in an old cabin nobody had lived in for years. He just started wiggling rocks in the fireplace until he found one that was loose, and there was the money, right behind it." "Aw," the boy said, but he cut his eyes toward the cabin, then looked quickly away. "I guess you're right, kid. Well, I better go. Merry Christmas." "Merry Christmas, mister." Alan walked about a hundred yards, then looked over his shoulder. The boy was still standing there. Alan waved, the boy waved back, then the path turned behind a laurel thicket and the highway came into view. Alan stopped behind the thicket and peeked cautiously around. The boy's gun was propped against the wall by the open door of the cabin. Alan waited. In a few minutes there was a whoop from inside the cabin and the boy burst out the door -waving a handful of bills. He ran up the path toward his house, and Alan could hear him yelling. "Pa! Ma! Come here! Look what I found!" Alan turned and walked quickly down the path to the car. What a weird night. He must have dreamed that stuff about the old woman and all. Still, he had put the presents on the porch, and he had known where the money was. This was going to take some sorting out. He got into the car and started it, still preoccupied. It had to be some kind of dream, he was sure of it. What else could it be? He put the car in gear and twisted around to look out the back window for traffic before he pulled out into the road. And in the back seat, lying folded among the Christmas presents, was the Star of Bethlehem quilt. = 0l(lllllMII(flll)ltltllllllH11l lltrilllli;i(MfiriMf(li/IHIIllll(l(MIIUIinilM(llll)irnilfllllllMt(IMUIIIllimMIIIII)ltllIIIIIIIIlllllimil>tlMllttlMimtmi1l II11II l>IIUIMItIltnilll)IIIIIIH(tin = *** ¿_ S . i:¡ ? "A ?* IKf Sonnet On a November Day This warm November day we tramp the lane and climb its narrow winding path uphill; shy birds in thickets view us with disdain, and flee in coveys to a distant rill. We pass by Esther's house, and old gray barn, where cured tobacco hangs in golden leaf; then come to spicy-smelling pines that warn of past glad Christmases and present grief. We mount the hill and reach its grassy crest; the Tygart Valley spreads its fields below. We pause to triumph and, fatigued, to rest, and listen to the wind's relentless flow. From here, we scan our ancient Planet Earth, and return fulfilled to home and blazing hearth. —Paula Wells j-wî e¿ IoniumiHmimmtMimiimiiiiiiimiHiimmmuiimmiiimiiiim......iuiimniimiimiimimiHis ?« mÄ il X*5 ^vvX * ·· ·>· ' S \ Iw y°^ ./:·'·¦··' ? xxxxxx>oo