Variation in Preen Oil Composition Pertaining to Season, Sex, and Genotype in the Polymorphic White-Throated Sparrow

Abstract

Evidence for the the ability of birds to detect olfactory signals is now well documented, yet it remains unclear whether birds secrete chemicals that can be used as social cues. A potential source of chemical cues in birds is the secretion from the uropygial gland, or preen gland, which is thought to waterproof, maintain, and protect feathers from ectoparasites. However, it is possible that preen oil also may be used for individual recognition, mate choice, and signalling social/sexual status. If preen oil secretions can be used as socio-olfactory signals, we should be able to identify the volatile components that could make the secretions more detectable, determine the seasonality of these secretions, and determine whether olfactory signals differ among relevant social groups. We examined the seasonal differences in volatile compounds of the preen oil of captive white-throated sparrows, Zonotrichia albicollis. This species is polymorphic and has genetically determined morphs that occur in both sexes. Mating is almost exclusively disassortative with respect to morph, suggesting strong mate choice. By sampling the preen oil from captive birds in breeding and non-breeding conditions, we identified candidate chemical signals that varied according to season, sex, morph, and species. Linear alcohols with a 10-18 carbon chains, as well as methyl ketones and carboxylic acids, were the most abundant volatile compounds. Both the variety and abundances of some of these compounds were different between the sexes and morphs, with one morph secreting more volatile compounds in the non-breeding season than the other. In addition, 12 compounds were seasonally elevated in amount, and were secreted in high amounts in males. Finally, we found that preen oil signatures tended to be species-specific, with white-throated sparrows differing from the closely related Junco in the abundances and/or prevalence of at least three compounds. Our data suggest roles for preen oil secretions and avian olfaction in both non-social as well as social interactions.

Conspecific olfactory preferences and interspecific divergence in odor cues in a chickadee hybrid zone

“…To test for differences between black-capped and Carolina chickadees in uropygial oil chemical profiles, we first conducted a principal components analysis (PCA) on the transformed gas chromatograph data (N = 81) to reduce the dataset of 146 different compounds into a smaller number of principal components (PCs). PCA is the most common method used to analyze avian preen oil chemistry (Amo et al, 2012;Fischer, Haliński, Meissner, Stepnowski, & Knitter, 2017;Leclaire et al, 2012;Lopez-Perea & Mateo, 2019;Shaw, Rutter, Austin, Garvin, & Whelan, 2011;Tuttle et al, 2014;Whittaker et al, 2013;Whittaker et al, 2019;Whittaker et al, 2018;Whittaker et al, 2010;Zhang et al, 2013) and it allows an examination of which factors best explain the main axes of variation in our data, represented by PCs. We used a multivariate analysis of variance (MANOVA) on nontrivial principal components selected based on comparing a scree plot of the principal components with a broken-stick distribution (Jackson, 1993), using species, date, sex, and all interactions as fixed factors.…”

“…PCA is the most common method used to analyze avian preen oil chemistry(Amo et al, 2012;Fischer, Haliński, Meissner, Stepnowski, & Knitter, 2017;Leclaire et al, 2012;Lopez-Perea & Mateo, 2019;Shaw, Rutter, Austin, Garvin, & Whelan, 2011;Tuttle et al, 2014;Whittaker et al, 2013;Whittaker et al, 2019; PCA is the most common method used to analyze avian preen oil chemistry(Amo et al, 2012;Fischer, Haliński, Meissner, Stepnowski, & Knitter, 2017;Leclaire et al, 2012;Lopez-Perea & Mateo, 2019;Shaw, Rutter, Austin, Garvin, & Whelan, 2011;Tuttle et al, 2014;Whittaker et al, 2013;Whittaker et al, 2019; …”

Histological and Morphological Study of the Uropygial Gland in Gull (Larus canus)

“…[4] Secretion of this gland play an important role in a feather maintenance, waterproofing feather, and may be associated with intraspecific communication and defense against the microbial, parasitic agent and predators . [5,6,7,8,9] However, in few birds like…”

House sparrow uropygial gland secretions do not attract ornithophilic nor mammophilic mosquitoes

“…Different compounds, including octenol, ammonia and lactic acid, have been reported as attractants to mammophilic mosquitoes such as Anopheles gambiae (Takken & Knols, ). Birds produce, in their uropygial gland, a mixture of organic compounds that varies between species, ages and sexes (Tuttle et al ., ; Moreno‐Rueda, ), which they spread over their plumage when preening and which mainly functions as waterproofing and conditioning for plumage. This secretion has been reported to attract insect vectors such as mosquitoes (Russell & Hunter, ), whereas other studies have found the opposite (i.e.…”