Evolutionary Ecology Group

One cardinal function of the avian uropygial gland and its oily secretions is protection against micro-organisms that may harm the feathers or developing embryos of the hosts. We studied this hypothesis by the phylogenetic comparative approach across 132 European bird species. Our results lend support for the defence hypothesis because gland size (1) correlated positively with total eggshell surface area, (2) increased much from non-breeding to breeding season in social species and (3) was larger in species inhabiting humid habitats. Our manuscript was recommended for publication in the Biological Journal of the Linnean Society. Authors with asterisk are Evol Ecol group members, while those marked with boldface are supported by a CNCSIS grant (PN II. RU TE 291/2010).

Vincze O*, Vágási CI*, Kovács I, Galván I, Pap PL*. Risk of bacterial infection and the seasonally dynamic activity of the uropygial gland in European birds.

In a study we aimed at investigating some physiological correlates of problem-solving success in a wild bird species to shed light on possible mechanisms and innate qualities that enable the animals to cope with new challenges or inventing new solutions to old problems. Physiology was characterized through non-skeletal mass (i.e. condition), coccidian parasite infestation level, antioxidant status, oxidative damage and corticosterone stress responsiveness. All these aspects of physiological state are linked to neural processes and could influence cognitive capacities, though such associations are poorly understood. To this end, house sparrows were tested in four food acquisition tasks by presenting to them feeding dishes that were designed such that food could have been accessed only with innovative problem-solving (e.g. remove the cover of the dish). We found that physiological traits may predict the problem-solving capacity of birds. Generally, birds in good physiological condition were more prone to innovative feeding. Our results were submitted to Behavioral Ecology and the manuscript is now under revision based on the constructive criticism raised by two reviewers. Authors marked with boldface are financed by a CNCSIS research grant (PN II. RU TE 291/2010).

Bókony V, Lendvai ÁZ, Vágási CI, Pătraș L, Pap PL, Németh J, Vincze E, Papp S, Preiszner B, Seress G, Liker A. Necessity or capacity? Physiological state predicts problem-solving performance in house sparrows.

One new article signed by one of the group members, Orsolya Vincze, got published. Orsolya and her collaborators analysed a large dataset about parental care in several Kentish and snowy plover populations to distinguish whether this complex social behaviour is environmentally and/or genetically determined.

Vincze O, Székely T, Küpper C, AlRashidi M, Amat JA, Ticó AA, Burgas D, Burke T, Cavitt J, Figuerola J, Shobrak M, Montalvo T, Kosztolányi A 2013. Local Environment but Not Genetic Differentiation Influences Biparental Care in Ten Plover Populations. PLoS ONE 8: e60998.

Today, 12th February 2013, is the 204th anniversary of Charles Robert Darwin’s birth.
Check out the website of International Darwin Day Foundation.

Our manuscript dealing with the physiological and morphological underpinnings of predator escape behaviour by prey and submitted in Journal of Evolutionary Biology was accepted for publication. Morphology – wing area and aspect ratio; physiology – haematocrit. Authors marked with bold are financed by a CNCSIS grant (TE 291/2010).

Møller AP, Vágási CI and Pap PL 2013. Risk-taking and the evolution of mechanisms for rapid escape from predators. Journal of Evolutionary Biology in press.

Update, 27 April 2013:
The final version is out and can be accessed here.

All the 3 in press papers of our group are now accessible as online early (see the links below).

Pap PL, Costică A, Vágási CI, Benkő Z and Vincze O 2013. Sex ratio and sexual dimorphism of three lice species with contrasting prevalence parasitizing the house sparrow. Journal of Parasitology (in press). URL

Pap PL, Vágási CI, Bărbos L and Marton A 2013. Chronic coccidian infestation compromises flight feather quality in house sparrows, Passer domesticus. Biological Journal of the Linnean Society (in press). URL

Czirják GÁ, Pap PL, Vágási CI, Giraudeau M, Mureşan C, Mirleau P and Heeb P 2013. Preen gland removal increases plumage bacterial load but not that of feather-degrading bacteria. Naturwissenschaften (in press). URL

In an attempt to integrate behaviour, morphology and physiology in an evolutionary context, we (Møller et al.) conducted a phylogenetic comparative analysis using 63 species of European birds. Specifically, we sought for morphological (wing area, aspect ratio – determinants of flight capacity) and physiological (haematocrit – proxy of oxygen transport) underpinnings of the risk-taking behaviour expressed as flight initiation distance when approached by a predator (human observer). The manuscript was submitted to Journal of Evolutionary Biology and is now under major revision.

This post provides an abstract of what we achieved in 2012 both within and out of the scope of our running CNCSIS grant (#TE 291/2010).

The year 2012 was quite good compared to our Evolutionary Ecology Group’s balance in previous years. We published two papers (Journal of Avian Biology and PLoS ONE) and have three papers accepted for publication (Journal of Parasitology, Biological Journal of the Linnean Society and Naturwissenschaften). We showed that (i) feather mites are best described as commensals of their avian hosts (Galván et al. 2012 J Avian Biol 43: 273–279), (ii) moult rate and feather quality are traded-off in house sparrows, especially in case of lower-quality birds (Vágási et al. 2012 PLoS ONE 7: e40651), (iii) among three phthirapteran lice species infesting house sparrows, the most prevalent one has the more egalitarian sex ratio and the least pronounced female-biased sexual size dimorphism (Pap et al. 2013 J Parasitol in press), (iv) coccidian infestation has both short- and long-term adverse effects on flight feather quality of house sparrows (Pap et al. 2013 Biol J Linn Soc in press), and (v) the absence of the uropygial gland, and thus blocked access to preen oils, did not result in increased feather-degrading bacteria load, but to increased other cultivable bacteria load on the plumage of house sparrows (Czirják et al. 2013 Naturwissenschaften in press). We have also submitted for review a manuscript in Journal of Evolutionary Biology dealing with the physiological, morphological and behavioural underpinnings of predator escape by prey. We have also raw data or partially analysed data from 8 different studies (4 experimental, 2 correlative, 3 comparative), which we plan to at least in part finalize this year. These studies range from physiology (immune investment, oxidative stress, corticosterone stress response) and morphology (feather quality, sexual signals) till behaviour (cognitive ability) and their potentially coupled evolutionary path.

So, we trust to attain at least a similar sabbatical in 2013.

The above results would have not been possible to reach without the altruistic help of a large number of undergrad and master students recruited in our Evolutionary Ecology Group at the University of Babeş-Bolyai, Cluj Napoca, Romania. Thank you again!

Our manuscript on the in vivo effect of preen gland on feather-degrading and other cultivable bacteria loads was accepted for publication in Naturwissenschaften. Authors marked with boldface are supported by a CNCSIS grant (PN II. RU TE 291/2010).

Czirják GÁ, Pap PL, Vágási CI, Giraudeau M, Mureşan C, Mirleau P and Heeb P 2013. Preen gland removal increases plumage bacterial load but not that of feather-degrading bacteria. Naturwissenschaften (in press).

Abstract         The preen gland is a holocrine sebaceous gland of the avian integument which produces an oily secretion that is spread on the plumage during preening. It has been suggested that birds may defend themselves against feather-degrading bacteria (FDB) and other potential pathogens using preen gland secretions. However, besides some in vitro studies, the in vivo bacterial inhibitory effects of the preen oil on the abundance of feather-associated bacterial species has not yet been studied in passerines. Here we tested the effect of gland removal on the abundance of FDB and other-cultivable bacterial loads (OCB) of male house sparrows (Passer domesticus). Our results did not support earlier results on in vitro antibacterial activity of preen oil against FDB since the absence of the preen gland did not significantly affect their loads related to the control birds. In contrast, we found that preen gland removal led to higher loads of OCB. This result suggests that the antimicrobial spectrum of the preen oil is broader than previously thought and that, by reducing the overall feather bacterial loads, the preen gland could help birds to protect themselves against a variety of potentially harmful bacteria.

We conducted a short experiment a couple of years ago to test the assertion that avian uropygial gland secretions are spread onto the plumage during the act of preening at least in part to keep feather-degrading bacteria within bounds. However, this function of the preen oils was tested mostly in vitro. Aviary house sparrows (Passer domesticus) were either glandectomized (surgical gland removal) or sham-operated (control). Glandectomy served to deprive birds from coating their plumage with oils that might block keratinolytic or feather-associated bacteria. We found that the change (post- minus pre-treatment) in the abundance of feather-degrading bacilli was not significant after one month, while that of other cultivable bacteria substantially increased in the glandectomized birds. We discuss the sanitation function of the gland oils and the possible sources of discrepancy between previous in vitro and our in vivo results.

Our study was submitted to Naturwissenschaften and now has a ‘moderate corrections needed’ decision.

Czirják GÁ, Pap PL, Vágási CI, Giraudeau M, Mureșan C, Mirleau P and Heeb P. Preen gland removal affects the abundance of feather-associated bacteria in house sparrows (Passer domesticus).