Begging, food provisioning, and nestling competition in great tit broods infested with ectoparasites

Abstract

Ectoparasites are a ubiquitous environmental component of breeding birds, and it has repeatedly been shown that hematophagous ectoparasites such as fleas and mites reduce the quality and number of offspring of bird hosts, thereby lowering the value of a current brood. Selection acting on the hosts will favor physiological and behavioral responses that will reduce the parasites' impact. However, the results of the few bird studies that addressed the question of whether parasitism leads to a higher rate of food provisioning are equivocal, and the begging response to infestation has rarely been quantified. A change in begging activity and parental rate of food provisioning could be predicted in either direction: parents could reduce their investment in the brood in order to invest more in future broods, or they could increase their investment in order to compensate for the parasites' effect on the current brood. Since the nesdings are weakened by the ectoparasites they may beg less, but on the other hand they may beg more in order to obtain more food. In this study we show experimentally that (1) hen fleas (Ceratophyllus galtinae) reduce the body mass and size of great tit (Parus major) nestlings, (2) nesdings of parasitized broods more than double their begging rate, (3) die male parents increase the frequency of feeding trips by over 50%, (4) the females do not adjust feeding rate to the lowered nutritional state of nestlings, and (5) food competition among siblings of parasitized broods is increased. Ultimately the difference in the parental feeding response may be understood as the result of a sex-related difference in die trade-off of investing in current versus future broods.

Twofold cost of reproduction: an increase in parental effort leads to higher malarial parasitaemia and to a decrease in resistance to oxidative stress

“…Because ectoparasites may strongly modify the amount of parental effort [35,36], all nests were treated twice with a microwave appliance in order to kill all ectoparasites inhabiting the nest (see [37]). …”

Yolk androgens do not appear to mediate sexual conflict over parental investment in the collared flycatcher Ficedula albicollis

“…Previous studies have shown that it is possible that females and males respond to different components of nestling behaviour and phenotype, for example colour (Jourdie et al 2004, de Ayala et al 2007Ewen et al 2008;Galvan et al 2008;Tanner and Richner, 2008), size (reviewed in Slagsvold, 1997;Lessells, 2002), condition (e.g. Christe et al 1996) or visual vs. vocal cues of begging (Kilner, 2002, reviewed in Müller et al, 2007a. We studied whether yolk androgens could mediate sexual conflict over parental care in a small passerine bird, the collared flycatcher (Ficedula albicollis) by conducting two experiments.…”

Trophic structure of arthropods in Starling nests matter to blood parasites and thereby to nestling development

“…First, a negative correlation between DG densities and nestling body mass may be obscured by parental quality (Bauchau 1997) or by increased begging behaviour of parasitised nestlings, which leads to increased parental provisioning, as was found in the Great Tit (Parus major; Christe et al 1996). Bauchau (1997) found that mite densities did not directly influence body mass in Pied Flycatchers (Ficedula hypoleuca) and suggested that parental quality may have been influencing nestling growth.…”

“…Since ectoparasites have been shown to slow nestling growth and development, those nestlings exposed to high parasite densities may therefore reach their maximum weight later and may have more and prolonged parental food provisioning than nestlings exposed to low parasite densities (e.g. Christe et al 1996). In our case, this would mean that Starling nestlings exposed to low ectoparasite densities may reach their maximum mass at first measurement (day 10), and those exposed to high ectoparasite densities may reach their maximum mass later, i.e.…”