Coccidial infection does not influence preening behavior in American goldfinches

acta ethologica, Aug 2013

Preening behavior in birds is important for the maintenance of thermoregulatory and ornamental functions of plumage. It has been repeatedly demonstrated that birds trade off time between plumage maintenance and other activities. However, the condition-dependent constraints of preening remain virtually unstudied. Here, we present the first experimental test of the hypothesis that intestinal parasite infection impairs preening activity. We studied male American goldfinches (Spinus tristis), a species with carotenoid-based plumage coloration. Following pre-alternate (spring) molt, we manipulated the health of males by infecting some birds with Isospora spp. coccidia and keeping others free of the infection. Although the goldfinches increased preening throughout the captive period, we found no significant effect of coccidial treatment on preening behavior. The effect of coccidia on plumage maintenance may be more pronounced under natural conditions where birds have limited access to food and engage in more activities that might limit time available for preening.

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Coccidial infection does not influence preening behavior in American goldfinches

Adrian Surmacki Geoffrey E. Hill 0 ) Department of Avian Biology and Ecology, Faculty of Biology, Adam Mickiewicz University , Umultowska 89, 61-614 Pozna, Poland Preening behavior in birds is important for the maintenance of thermoregulatory and ornamental functions of plumage. It has been repeatedly demonstrated that birds trade off time between plumage maintenance and other activities. However, the condition-dependent constraints of preening remain virtually unstudied. Here, we present the first experimental test of the hypothesis that intestinal parasite infection impairs preening activity. We studied male American goldfinches (Spinus tristis ), a species with carotenoid-based plumage coloration. Following pre-alternate (spring) molt, we manipulated the health of males by infecting some birds with Isospora spp. coccidia and keeping others free of the infection. Although the goldfinches increased preening throughout the captive period, we found no significant effect of coccidial treatment on preening behavior. The effect of coccidia on plumage maintenance may be more pronounced under natural conditions where birds have limited access to food and engage in more activities that might limit time available for preening. - Plumage maintenance is an important behavior among birds, accounting for about 9 % of the daily time budged (Cotgreave and Clayton 1994; Walther and Clayton 2005). The primary functions of preening include: controlling ectoparasites load (Clayton et al. 2010), removing dirt and detritus (Lenouvel et al. 2009; Griggio et al. 2010), spreading preen wax over the surface of feathers (Moyer et al. 2003), and keeping feathers properly positioned. All of these activities are crucial for the maintenance of thermoregulatory function of plumage, which might be altered if the physical condition of feathers is disturbed either by soiling load, keratin-eating parasites, or disorder. Plumage maintenance can also help maintain plumage coloration. In many bird species, females use male coloration as a cue during mate choice (reviewed in Hill 2006). Ornamental plumage coloration can be compromised by soiling (e.g., Surmacki and Nowakowski 2007; Lenouvel et al. 2009; Griggio et al. 2010), and ectoparasites (Moreno-Rueda 2005) or enhanced by preen oil (e.g., Lpez-Rull et al. 2010). Feather maintenance is believed to be a time- and energyconsuming behavior (Cotgreave and Clayton 1994; Walther and Clayton 2005). Birds must trade off time and energy between preening and other behaviors such as foraging or scanning for predators (Redpath 1988; Cucco and Malacarne 1997; Randler 2005). Consequently, we may expect that any alteration of physiological condition may impose negative effects on preening activity. Surprisingly, this idea has been tested only once, using juvenile apapanes (Himatione sanguinea , Yorinks and Atkinson 2000). Individuals experimentally infected with malaria spent significantly less time preening than did healthy birds. Infected individuals also showed a reduction in activity, body mass, and fat stores (Yorinks and Atkinson 2000). Here, we experimentally tested the hypothesis that parasite infection affects preening behavior in male American goldfinches (Spinus tristis ), a sexually dichromatic songbird. Male goldfinches have bright-yellow carotenoid-based plumage coloration (McGraw et al. 2001) that females assess during mate choice (Johnson et al. 1993). We manipulated parasite infection status of birds by either infecting them with coccidia (Isospora sp.) or by curing them of coccidiosis with medicine. Coccidia are common intestinal parasite of many songbirds including house finches, Carpodacus mexicanus (Brawner et al. 2000). Their sporozoites feed on the epithelium of the small intestine, leading to significant impairment of absorption of various components of food (Hrak et al. 2004). To date, the effect of coccidia infection on preening has not been tested but coccidiosis is known to affect sexual display behavior in birds (e.g., Costa and Macedo 2005; Aguilar et al. 2008) and anti-predator behavior in mammals (Voek et al. 1998). Consequently, we predicted that infected individuals would spend less time preening. Material and methods We captured 57 wild male American goldfinches on the campus of the Auburn University in April 2010 using wire mesh traps baited with thistle seeds (see Hill (2002) for trapping method details). We registered standard biometric measurements: body mass (0.1 g), tarsus (0.01 mm), bill (0.01 mm), wing (0.5 mm), and tail length (1 mm). Additionally, we collected 1015 breast feathers from each bird before coccidia treatment and at the end of the experiment for ectoparasite examination. We estimated the age of birds as after second year (ASY) or second year (SY) based on plumage characters (Pyle 1997). We randomly divided the birds into four groups of 13, 16, 14, and 14 birds. The proportions of the two age classes (ASY/SY) in each cage were as follows: 11/2 (...truncated)


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Adrian Surmacki, Geoffrey E. Hill. Coccidial infection does not influence preening behavior in American goldfinches, acta ethologica, 2014, pp. 107-111, Volume 17, Issue 2, DOI: 10.1007/s10211-013-0159-z