Crest Feathers Research Articles

The crest phenotype in domestic chicken is caused by a 195 bp duplication in the intron of HOXC10

The Crest mutation in chicken shows incomplete dominance and causes a spectacular phenotype in which the small feathers normally present on the head are replaced by much larger feathers normally present only in dorsal skin. Using whole-genome sequencing, we show that the crest phenotype is caused by a 197 bp duplication of an evolutionarily conserved sequence located in the intron of HOXC10 on chromosome 33. A diagnostic test showed that the duplication was present in all 54 crested chickens representing eight breeds and absent from all 433 non-crested chickens representing 214 populations. The mutation causes ectopic expression of at least five closely linked HOXC genes, including HOXC10, in cranial skin of crested chickens. The result is consistent with the interpretation that the crest feathers are caused by an altered body region identity. The upregulated HOXC gene expression is expanded to skull tissue of Polish chickens showing a large crest often associated with cerebral hernia, but not in Silkie chickens characterized by a small crest, both homozygous for the duplication. Thus, the 197 bp duplication is required for the development of a large crest and susceptibility to cerebral hernia because only crested chicken show this malformation. However, this mutation is not sufficient to cause herniation because this malformation is not present in breeds with a small crest, like Silkie chickens.

Hearing in Indian peafowl (Pavo cristatus): sensitivity to infrasound.

Despite the excitement that followed the report of infrasound sensitivity in pigeons 40 years ago, there has been limited followup, with only eleven species of birds having auditory thresholds at frequencies below 250 Hz. With such sparse data on low-frequency hearing, there is little understanding of why some birds hear very low frequencies while others do not. To begin to expand the phylogenetic and ecological sample of low-frequency hearing in birds, we determined the behavioral audiogram of the Indian peafowl, Pavo cristatus. Peafowl are thought to use low frequencies generated by the males' tail feathers and wing flutters during courtship displays, and their crest feathers are reported to resonate at infrasound frequencies. The peafowl were able to respond to frequencies as low as 4 Hz, and their hearing range at 60 dB SPL extended from 29Hz to 7.065 kHz (7.9 octaves). Removing the crest feathers reduced sensitivity at their resonant frequencies by as much as 7.5 dB, indicating a modest contribution to detectability in that range. However, perforation of the tympanic membranes severely reduced sensitivity to low frequencies, indicating that sensitivity to low frequencies is mediated primarily by the ears and cannot be attributed to some other sensory modality.

Social paper wasp (Agelaia pallipes) predates songbird nestling

AbstractThe social paper wasp Agelaia pallipes is known to eat carrion and scavenge on vertebrates. There are few records of wasps predating vertebrates, including an attack on an adult hummingbird and the predation of bird nestlings. During a project monitoring reproductive behaviour of a neotropical songbird, the Lined Seedeater Sporophila lineola in south‐eastern Brazil, we recorded the predation of a four‐day‐old nestling by a social paper wasp. In the video, the adult female bird attempted to visit the nest prior to the predation. The male could be seen with its crest feathers erect after a wasp left the nest, when the nestling was presumably already dead. When we arrived at the nest to remove the camera, we found the nestling dead, and did not observe the parents in the vicinity. We also registered two other dead nestlings in a different nest with similar wounds. However, the conclusive cause of death of those nestlings is unknown. Nest predation is a major selective pressure in birds, and insects are rarely assumed to play a notable role in this process. Further research is needed to better understand the nature of the relationship between wasps and birds.

Biomechanics of the peafowl's crest reveals frequencies tuned to social displays.

Feathers act as vibrotactile sensors that can detect mechanical stimuli during avian flight and tactile navigation, suggesting that they may also detect stimuli during social displays. In this study, we present the first measurements of the biomechanical properties of the feather crests found on the heads of birds, with an emphasis on those from the Indian peafowl (Pavo cristatus). We show that in peafowl these crest feathers are coupled to filoplumes, small feathers known to function as mechanosensors. We also determined that airborne stimuli with the frequencies used during peafowl courtship and social displays couple efficiently via resonance to the vibrational response of their feather crests. Specifically, vibrational measurements showed that although different types of feathers have a wide range of fundamental resonant frequencies, peafowl crests are driven near-optimally by the shaking frequencies used by peacocks performing train-rattling displays. Peafowl crests were also driven to vibrate near resonance in a playback experiment that mimicked the effect of these mechanical sounds in the acoustic very near-field, reproducing the way peafowl displays are experienced at distances ≤ 1.5m in vivo. When peacock wing-shaking courtship behaviour was simulated in the laboratory, the resulting airflow excited measurable vibrations of crest feathers. These results demonstrate that peafowl crests have mechanical properties that allow them to respond to airborne stimuli at the frequencies typical of this species’ social displays. This suggests a new hypothesis that mechanosensory stimuli could complement acoustic and visual perception and/or proprioception of social displays in peafowl and other bird species. We suggest behavioral studies to explore these ideas and their functional implications.

The effects of hatching asynchrony on growth and mortality patterns in Eurasian Hoopoe Upupa epops nestlings

Growth is a fundamental life history trait in all organisms and is closely related to individual fitness. In altricial birds, growth of many traits is restricted to the short period between hatching and fledging and strongly depends on the amount of food that parents deliver and the extent of hatching asynchrony. However, empirical studies of energy allocation to growth of different body size traits as a function of hatching asynchrony are scarce. We studied growth and mortality of Eurasian Hoopoe Upupa epops, a species with a long breeding season and high brood size variance, whose nestlings show pronounced hatching asynchrony, in order to test how hatching asynchrony affects different growth traits in the context of territory quality, season and brood size. The growth of five body traits (body mass, and lengths of tarsus, third primary, bill and longest crest feather) was investigated to understand how it was affected by brood size, hatching date and order, and territory quality. In total, 241 nestlings from 39 nests were measured every 4 days in 2014 in south‐western Switzerland. Brood size, hatching date and hatching order had the strongest influence on growth trajectories, although tarsus growth was only marginally affected by these variables. Nestlings that hatched earlier than their siblings were heavier and had longer third primaries, bills and crest feathers compared with later‐hatched siblings. In territories of high quality, hatching order differences disappeared for body mass growth, but persisted for lengths of third primary, bill and crest feathers. Brood size was inversely associated with third primary, bill and crest feather lengths, but positively associated with body mass. Nestling mortality was higher in later‐hatched nestlings and in broods that were raised in territories of lower quality. Our study shows that in nestlings, energy was allocated differentially between body traits and this allocation interacted with hatching order and territory quality. Rapid mass gain by nestlings was prioritized in order to increase competitive ability. Our results provide support for the brood reduction hypothesis as an explanation of hatching asynchrony in Hoopoes.

Multi‐functional crest display in hoopoes Upupa epops

Animals can engage in visual displays, which may target conspecifics, heterospecifics or both. Here we studied the function of the flamboyant crest‐raising display of hoopoes Upupa epops in experiments performed with males in captivity. Males were exposed to sounds of a conspecific (male hoopoe song), a potential predator (human voice), and two controls (the song of a blackbird Turdus merula, and background noise). These stimuli were presented to males in the presence and absence of females. Males raised the crest with a significantly higher probability when confronted with stimuli indicating potential threats (rival mate or predator) than with controls. The crest display was frequent when confronted with both kinds of threats independently of the presence of a female, suggesting that it was directed to the predator and the rival male. The probability of raising the crest was not related to body condition, and there was a marginally but not significant negative relationship between probability of raising the crest and the number of black spots on the crest feathers, which may suggest that crest display could be informing about male quality. Therefore, male hoopoes display the crest in a heterospecific context in response to detection of potential threats, which could be a deceptive or pursuit‐deterrent signal. The results also support a role of the crest in sexual selection, suggesting that crest display in male hoopoes may serve multiple functions.

Multigene phylogeny and DNA barcoding indicate that the Sandwich tern complex ( Thalasseus sandvicensis, Laridae, Sternini) comprises two species

The crested terns are a group of six species of seabirds with a world-wide distribution closely allied to but larger than typical Sterna species. They are black-capped with elongated crest feathers and most have a bright yellow or orange to orange–red bill (Gochfeld and Burger, 1996). The taxonomic status of this group as a separate genus, Thalasseus, is gaining increasing acceptance following the publication of a molecular phylogeny demonstrating they form a strongly supported monophyletic clade (Bridge et al., 2005). One of the remaining taxonomic uncertainties in the Sternini is in the classification of the species complex of the Sandwich tern (Thalasseus sandvicensis), a taxon whose definition and limits have been controversial over the last century. Within this complex, there are three forms that have been classified either as subspecies or species. The most frequent treatment is to consider them as three subspecies: the Sandwich tern (T. s. sandvicensis) that breeds on the Atlantic and Mediterranean coasts of Europe, Cabot’s tern (T. s. acuflavidus) that breeds on the Atlantic coasts of North America and the Caribbean, and Cayenne tern (T. s. eurygnathus) that breeds on the Atlantic coast of South America from Argentina north to the Caribbean. The three races of Sandwich tern were originally described as distinct species (Baird et al., 1884), and due to their morphological and behavioral similarities were later suggested to be part of the same species complex (Baird et al., 1884; Junge and Voous, 1955), an issue that is still controversial (Gochfeld and Burger, 1996; Hayes, 2004). These taxa are morphologically very similar, with a few distinctions: the Sandwich tern is slightly larger with wider white margin on outer primaries, shorter bill and, paler upperparts (Olsen and Larsson, 1995). Cabot’s and Cayenne terns are virtually identical

Ecology and behaviour of the critically endangered Trinidad piping-guan Aburria pipile

From 1997 to 2001 we studied a group of 6 Trinidad piping-guans Aburria pipile, a crit- ically endangered species, in northern Trinidad. The group occupied a home range of 19 ha in highly disturbed secondary forest and around small farms, and often split into smaller groups. They spent 93.6% of the time in the forest canopy >5 m above ground and only 0.2% of the time on the ground (n = 48.1 h). In early morning (n = 18.7 h), they spent 80.3% of their time perched alert, 9.3% preen- ing, 3.9% flying, 3.6% walking, 2.4% feeding, 0.3% drinking, and 0.1% perched flapping. In late afternoon (n = 8.2 h), they spent 78.6% of their time perched alert, 12.8% preening, 3.7% walking, 3.0% feeding, 1.2% flying, and 0.7% drinking. At midday, they eluded observation. They foraged mostly on fruits (occasionally leaves or flowers) of 15 species of plants, with Virola surinamensis (Myristicaceae) constituting the primary item (33.3% of foraging bouts; n = 30). They drank water from epiphytic bromeliads. Drumming displays, produced mechanically by the wings in flight, were given intermittently throughout the morning and rarely in the afternoon. Singing occurred intermit- tently throughout the early morning and late afternoon. The song consisted of 3 to 7 plaintive whis- tles rising in pitch, delivered by lone individuals averaging 2.7 songs min -1 , in bouts of up to 30 min. Soft piping calls were usually given in a social context. Raised crest feathers appeared to be an aggressive display. Piping-guans rarely interacted with other species of birds. They were relatively unperturbed by human disturbance.

Multiple ornaments correlate with aspects of condition and behaviour in female northern cardinals, Cardinalis cardinalis

Male ornamentation in socially monogamous birds has been shown to provide information to potential mates on aspects of condition and behaviour. We studied female ornamentation in the socially monogamous, biparental northern cardinal to determine whether expressions of multiple ornaments correlate with aspects of female condition and behaviour. Expressions of the ornamental red-orange bill, red underwing feathers, head crest and blackish face mask were compared to several measures of condition, parental behaviour and intrasexual aggression. Red-orange bill colour of females was correlated with both body size and an index of body condition. Redness of the underwing feathers was correlated with body size, body condition, date of first nest produced and reproductive success. Face mask expression was correlated with both nestling feeding rate and level of intrasexual aggression. The length of head crest feathers did not correlate with any measured aspect of condition or behaviour. These results are consistent with the hypothesis that ornaments in female cardinals provide redundant information to prospective mates on aspects of female condition and behaviour.

Morphological signals of sex and status in Spotted Bowerbirds

The Spotted Bowerbird, Chlamydera maculata, appears to be sexually monomorphic. We caught and marked 118 birds in central Queensland, and sexed 88 using molecular methods. We found that our catch was strongly male-biased, both at bower sites and at non-bower feeding sites. We continued to observe the bird's behaviour after their release and so sub-divided males into sexual status groups as either bower-owners or non-owners. We searched for morphological measures, subjectively judged colour differences and quantitatively collected spectral measures of the visual properties of the crest feathers that would allow us to separate birds of differing sex and status. We found that bower owners had larger crests than non-owner males or females and that crest area provided the most accurate predictor of a bird's sex and status in a discriminant function analysis. We studied a cohort of seven males who went from non-owners to bower owners over three years, and found that their change in status was accompanied by a change in crest size—the only significant change in their morphology. Crest size did not relate to the mating success of a bower-owner. Instead, we suggest why the crest may differ between status groups and the implications that this may have for the sexual behaviour of male and female Spotted Bowerbirds.

Agonistic Behaviour Among Blue Tits At a Winter Feeding Station

Agonistic behaviour in Blue Tits was observed at a feeding station from January 26 to March 15, 1959. The behaviour observed when two birds met at the feeding station was broken down into separate elements to relate behaviour with underlying tendencies to attack, escape, or stay. Encounters between birds were brief and considered instantaneous. The presence of an erect crest and fluffed body feathers was associated with an increased tendency to escape. Facing the rival, horizontal body, erect nape, raised wings, and fanned tail were indicators of an increased attack tendency. An open beak was given largely by an aggressive bird with a strong tendency to stay rather than attack. Maximum probabilities of correctly predicting the outcome of an encounter between two birds by using different combinations of behaviour elements were 0.48 for attack, 0.94 for escape, and 0.79 for staying. Hence much of a bird's motivation to attack or stay was not reflected in its external behaviour. Attack and escape both decreased in frequency from January through March. Birds also tolerated each other at closer distances. Likewise the behaviour elements associated with attack and escape tendencies diminished in frequency. This reduced the observer's ability to predict from a bird's behaviour if it would attack or escape. The reduced agonistic behaviour with season may have been the result of increased social organization of the birds using the feeding station, habituation to the strange stimuli associated with the feeder, or to increased hunger. The agonistic behaviour elements had strong signal value. If a bird showed behaviour elements indicative of an escape tendency, the rival escaped less and stayed more. Likewise aggressive behaviour in one bird elicited increased escape and reduced attack in the second. Finally, appeasement behaviour in one bird resulted in less attack and less escape in the second bird. The probabilities of attack, escape, and staying following a particular combination of behaviour elements changed with season. Therefore behaviour elements are not perfect reflectors of the underlying motivation of a bird.

Fear responses in Emberiza spp.

In Buntings, fear responses express five main tendencies: to flee, to hide, to watch the feared object, and to give certain calls. Alarm, mobbing, freezing and hiding are discussed. Fear responses to predators near the nest, and distraction displays are described. Resting attitudes occur irrelevantly during fear in the Buntings. They have a submissive function, but are not always caused by fear of another bird. The crest feathers (and more rarely those of the back) are sometimes raised in fear. Possible causes of these types of behaviour are considered.