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Measurement of Chemical Emissions in Crested Auklets (Aethia cristatella)

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This report presents the first quantitative estimates of emission rates for chemical signals in a bird—the crested auklet (Aethia cristatella). Volatile emissions from live birds were captured in a purified airstream onto polymer traps. Traps were eluted with methanol and analyzed with gas chromatography-mass spectrometry. The volatile collection chamber was field-calibrated with an in-line bubbler and synthetic octanal, the dominant constituent of the crested auklet’s citruslike odor. The result is an index of volatile chemical emissions within a small population of wild crested auklets at Big Koniuji Island, AK, USA. The average emission rate for octanal was 5.7 μl/50 min. Males and females did not differ in their emission rates (t (0.05)two-tailed = 0.44, P = 0.66). There was a sevenfold difference between minimum and maximum emission rates. Prevalence of tick infection (2%) was low despite the high abundance of ticks in the colony. The crested auklet with the lowest chemical emission rate was heavily parasitized by ticks.
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1
Article Title
Measurement of Chemical Emissions in Crested Auklets (
Aethia
cristatella
)
2
Journal Name
Journal of Chemical Ecology
3
Corresponding
Author
Family Name
Douglas
4
Particle
5
Given Name
Hector D.
6
Suffix
III
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Organization
University of Alaska Fairbanks
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Division
Institute of Marine Science
9
Address
Fairbanks 9970, Alaska, USA
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e-mail
hddouglas@gmail.com
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Schedule
Received
27 March 2006
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Revised
2 June 2006
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Accepted
21 June 2006
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Abstract
This report presents the first quantitative estimates of emission rates for
chemical signals in a bird—the crested auklet (Aethia cristatella). Volatile
emissions from live birds were captured in a purified airstream onto polymer
traps. Traps were eluted with methanol and analyzed with gas chromatography-
mass spectrometry. The volatile collection chamber was field-calibrated with an
in-line bubbler and synthetic octanal, the dominant constituent of the crested
auklet’s citruslike odor. The result is an index of volatile chemical emissions
within a small population of wild crested auklets at Big Koniuji Island, AK, USA.
The average emission rate for octanal was 5.7 µl/50 min. Males and females
did not differ in their emission rates (t
(0.05)two-tailed
= 0.44, P = 0.66). There was
a sevenfold difference between minimum and maximum emission rates.
Prevalence of tick infection (2.1%) was low despite the high abundance of ticks
in the colony. The crested auklet with the lowest chemical emission rate had 14
ticks attached to the face, whereas nearly all other crested auklets had no ticks.
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Keywords
separated by ' - '
Crested auklet - Chemical emissions - Chemical signal - Octanal -
Ectoparasites - Repellents - Chemical defense
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Foot note
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file://D:\Programs\Metadata\temp\jec69164.htm
... Aside from studies of the uropygial gland, intraspecifi c patt erns of avian compounds are rarely noted in the literature. Important exceptions include adult Crested Auklets, pitohuis, and Antarctic Prions (Pachyptila desolata), which exhibit individual variation in the chemical substances they produce-in the rate of odor emissions (Douglas 2006a), concentration of feather toxins (Dumbacher et al. 2000), and volatile compounds extracted from plumage (Bonadonna et al. 2007), respectively. No striking chemical diff erences are evident between the sexes (Dumbacher et al. 2000, Hagelin et al. 2003, Bonadonna et al. 2007. ...
... L. Jones pers. obs.; see also Douglas 2006a). The tick transmits disease, including the spirochete Borrelia and viruses (Muzaff ar and Jones 2004). ...
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... Predictably, chemical sampling methods that directly capture compounds released into the environment immediately surrounding the animal (its 'headspace') reveal fewer analytes compared to liquid extraction techniques. By selectively trapping volatile chemicals, systems such as solid phase microextraction (SPME), thermal desorption (TD), or other polymer trapping techniques (e.g., SuperQ or Tenax) deliver a more discerning representation of the natural volatilome profile [51][52][53]. For example, Gabiriot et al. compared traditional solvent extraction with SPME and TD methods to explore the musky odour of the blue petrel (Halobaena caerulea) [51]. ...
... Similarly, solvent-free gas-phase sampling techniques were used to capture the short-chain saturated and mono-unsaturated aldehydes that give rise to the distinctive citrus-like aroma of crested auklets (Aethia cristatella) and whiskered auklets (A. pygmaea) [52][53][54]. ...
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Thesis
Full-text available
Crested auklets (Aethia cristatella) are small colonial seabirds that display an ornamental feather crest and emit a citrus-like odorant during the breeding season. In this study odors and ornaments were investigated as possible signals of mate quality. Crest size was negatively correlated with the stress hormone corticosterone in males, but this was not the case in females. Body condition was negatively correlated with corticosterone in females, but this was not the case in males. Corticosterone levels were interpreted as an index of physiological condition, and it was concluded that males with longer crests were more competent at meeting the social and energetic costs of reproduction. I hypothesized that the crested auklet odorant: 1) functions as a chemical defense against ectoparasites, 2) is assessed as a basis for mate selection, 3) is facilitated by steroid sex hormones. Laboratory and field experiments showed that synthetic replicas of the crested auklet odorant repelled, impaired, and killed ectoparasites in a dose-dependent fashion. Chemical concentrations in plumage were at least sufficient to repel and impair ectoparasites. Chemical emissions from breeding adult crested auklets peaked at the time of egg hatching when young are most vulnerable to tick parasitism. In males, chemical emissions were correlated with crest size, a basis for mate selection. Presentation of synthetic aldehydes elicited behaviors similar to those that occur during courtship. Captive crested auklets responded preferentially to synthetic replicas of their odor, and the highest frequency of response occurred during early courtship. These results show that the chemical odor could be a basis for mutual mate selection. Production of the chemical odorant may be facilitated by steroid sex hormones since octanal emission rates were correlated with progesterone in males. Finally it was determined that the chemical composition of odorants in crested auklets and whiskered auklets (A. pygmaea) differed in three key respects. This suggests that an evolutionary divergence occurred in the odorants of the two species similar to what has been suggested for ornamental traits. In conclusion, crested auklets appear to communicate with odors and ornaments, and these signals may convey multiple messages regarding condition, quality, and resistance to parasites.
Thesis
Full-text available
Crested auklets (Aethia cristatella) are small colonial seabirds that display an ornamental feather crest and emit a citrus-like odorant during the breeding season. In this study odors and ornaments were investigated as possible signals of mate quality. Crest size was negatively correlated with the stress hormone corticosterone in males, but this was not the case in females. Body condition was negatively correlated with corticosterone in females, but this was not the case in males. Corticosterone levels were interpreted as an index of physiological condition, and it was concluded that males with longer crests were more competent at meeting the social and energetic costs of reproduction. I hypothesized that the crested auklet odorant: 1) functions as a chemical defense against ectoparasites, 2) is assessed as a basis for mate selection, 3) is facilitated by steroid sex hormones. Laboratory and field experiments showed that synthetic replicas of the crested auklet odorant repelled, impaired, and killed ectoparasites in a dose-dependent fashion. Chemical concentrations in plumage were at least sufficient to repel and impair ectoparasites. Chemical emissions from breeding adult crested auklets peaked at the time of egg hatching when young are most vulnerable to tick parasitism. In males, chemical emissions were correlated with crest size, a basis for mate selection. Presentation of synthetic aldehydes elicited behaviors similar to those that occur during courtship. Captive crested auklets responded preferentially to synthetic replicas of their odor, and the highest frequency of response occurred during early courtship. These results show that the chemical odor could be a basis for mutual mate selection. Production of the chemical odorant may be facilitated by steroid sex hormones since octanal emission rates were correlated with progesterone in males. Finally it was determined that the chemical composition of odorants in crested auklets and whiskered auklets (A. pygmaea) differed in three key respects. This suggests that an evolutionary divergence occurred in the odorants of the two species similar to what has been suggested for ornamental traits. In conclusion, crested auklets appear to communicate with odors and ornaments, and these signals may convey multiple messages regarding condition, quality, and resistance to parasites.
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During the breeding season, female and male Crested Auklets (Aethia cristatella; Alcidae) emit a pungent citruslike odor from their plumage. Previous experiments showed that captive birds oriented toward sources of the natural odor and toward isolates of its major constituents, cis-4 decenal and octanal, and avoided a noxious odor. In a blind experiment we manipulated odor on 12 life-sized, realistic Crested Auklet models (6 males, 6 females) to test for a social or sexual preference for the odor isolates in a natural setting. Based on the quantified behavior of 555 males and 280 females that approached the models at a breeding colony, we found no evidence for a sexual preference for models with added odor. Female auklets that approached male models with artificially added odor were no more likely to perform sexual displays than females that approached control models with less odor. Fewer males approached female models but the effect was the same: males that approached female models with artificially added odor were no more likely to perform sexual displays. However, males approached scented male models more closely and for longer duration than they approached control male models, and females approached scented male models more closely. Our findings confirm previous experiments with captive birds and further suggest that Crested Auklets' plumage odor serves at least a general social function. Estudio Experimental de Campo de la Función del Olor de las Plumas en Aethia cristatella Resumen. Durante la estación reproductiva, el plumaje del macho y la hembra de Aethia cristatella (Alcidae) emite un olor picante-cítrico. Experimentos previos han demostrado que las aves en cautiverio se orientan hacia fuentes de olor natural y hacia extractos de sus principales constituyentes, cis-4 decano y octano, y evitan un olor nocivo. En un experimento a ciegas, manipulamos el olor en 12 modelos de tamaño real de A. cristatella (6 machos y 6 hembras) para probar la preferencia sexual o social por los extractos en un ambiente natural. Basados en el comportamiento cuantitativo de 555 machos y 280 hembras que se acercaron a los modelos en la colonia reproductiva, no encontramos ninguna evidencia por una preferencia sexual por los modelos con el olor añadido. Las hembras de A. cristatella que se aproximaron a los modelos con el olor artificial añadido no presentaron una probabilidad mayor de realizar despliegues sexuales que las hembras que se acercaron a modelos con poco olor (control). Sin embargo, los machos se acercaron más y por más tiempo a los modelos de macho con olor que a los modelos de macho control, y las hembras se acercaron más a los modelos de macho con olor. Nuestros resultados confirman experimentos previos en aves en cautiverio y sugieren que el olor del plumaje de A. cristatella tiene por lo menos una función social general.
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