Bird-Ectoparasite Interactions, Nest Humidity, and Ectoparasite Community Structure

Abstract

Abstract. Host nests are the key habitat for ectoparasite species that live and reproduce within the nest material. Nest properties can influence host and parasite reproductive success, and therefore the outcome of host-parasite interactions, as well as the composition of parasite communities. Previous correlational results suggested that nest humidity may increase the negative effect of fleas on Great Tit (Parus major) reproductive success. Since the causality of the relationship was unknown, we simultaneously manipulated both hen flea (Ceratophyllus gallinae) infestation and nest humidity in order to investigate: (1) the effect of flea infestation on nest humidity, (2) the effect of nest humidity on the prevalence of flea infestations, (3) the effect of nest humidity on adult flea survival and reproduction, (4) the interaction between flea infestations and nest humidity on Great Tit reproductive performance, and (5) the effect of both factors on secondary infestations by ectoparasitic Protocalliphora flies. The present study provides the first example of an ectoparasite acting as a physical ecosystem engineer where nest humidity increased as a result of flea infestations. In experimentally uninfested nests, infestation of hosts by immigrant fleas was more frequent in nests with reduced humidity. In experimentally infested nests, manipulation of humidity did not significantly affect the number of adult fleas or larvae. Hen flea infestation reduced Great Tit nestling body mass, tarsus length, and wing length, as well as the number of young fledged. The detrimental effect of the fleas on Great Tit reproduction was not altered by our modifications of nest humidity. The effect of fleas on nestling growth parameters and the number young fledged did not vary significantly with the seasonal decrease in reproductive performance of the birds, or with the number of young in the brood. The prevalence of secondary infestations by Protocalliphora was higher in nests with reduced humidity, and in nests experimentally infested with fleas. The numbers of Protocalliphora pupae were lower in flea-infested nests. This study provides the first experimental evidence that an abiotic factor within nests can affect ectoparasite infracommunity structure. It also provides the first evidence for an interspecific association between two ectoparasite species.

Mammal density and patterns of ectoparasite species richness and abundance

“…Several studies have focused on the effect of abiotic factors on the structure of ectoparasite communities (Krasnov et al 1997;Heeb et al 2000). Nest properties, such as humidity, influence the abundance of fleas in birds (Heeb et al 2000), whereas Krasnov et al (1997) showed the importance of host habitat on the abundance of fleas in rodents.…”

“…Nest properties, such as humidity, influence the abundance of fleas in birds (Heeb et al 2000), whereas Krasnov et al (1997) showed the importance of host habitat on the abundance of fleas in rodents. A positive effect of increasing host density on prevalence and abundance of two flea species was observed in the desert rodent Gerbillus dasyurus (Krasnov et al, in press).…”

Aromatic plants in nests of the blue tit Cyanistes caeruleus protect chicks from bacteria

“…Blow Xy larvae develop into three successive larval stages before pupating (Bennett and Whitworth 1991). The tiny Wrst-stage larvae are particularly diYcult to detect so that our estimate of blow Xy infestation intensity only included the total number of second-stage larvae, third-stage larvae and pupae, following the protocols applied by Hurtrez-Boussès (1996) and Heeb et al (2000).…”

Interactions between climate, host refuge use, and tick population dynamics

“…Although some ticks can respond to host cues and move towards the host over short distances (Barnard 1986;Heeb et al 2000;Milne 1950), they risk desiccation, predation and the uncertainty of locating their more mobile hosts (Hair and Bowman 1986;Petney et al 1983). Instead, many ticks adopt a sit-and-wait strategy in favourable microclimates and rely on the behaviour of host individuals to make contact.…”

“…Instead, many ticks adopt a sit-and-wait strategy in favourable microclimates and rely on the behaviour of host individuals to make contact. For instance bird ectoparasites in nests rely on host individuals reusing the nest (Brown and Bomberger Brown 1986;Heeb et al 2000), and mammal ectoparasites that detach in burrows (Butler and Roper 1996;Roper et al 2002) have a good chance that the same individual may reuse the burrow, or a conspecific will share use of the burrow, making host contact highly probable.…”