Nest sanitation in passerine birds: implications for egg rejection in hosts of brood parasites

Abstract

We reviewed information on nest sanitation (nest cleaning) by passerine birds because the act of cleaning nests is thought to be associated with egg rejection by hosts of brood parasites, and yet there has been no synthesis of the literature on nest sanitation. In the first part of the review, we summarized information on nest sanitation. We found that birds remove a variety of objects from nests such as egg shells, fecal sacs, pieces of vegetation, invertebrate parasites, dead chicks, uneaten food, and occasionally unhatched eggs. Fecal sac removal, the most commonly considered type of nest sanitation behavior, is not divided equally between the sexes across species; females remove more fecal sacs than males. In addition, larger species tend to carry fecal sacs farther than smaller species. In the second part of the review, we discuss the importance of nest sanitation in the evolution of egg rejection behavior of brood parasite hosts. Recent studies involving the experimental addition of non-egg-shaped objects to nests or to the vicinity of nests suggest that nest sanitation plays a role in host rejection of avian brood parasitism. Most objects added to nests prior to hatching (usually hard) and after hatching (usually soft) were rejected. In a logistic regression model, shape and size were the significant factors in eliciting rejection for all hosts that received experimental non-egg objects added to their nests prior to hatching. Nest sanitation may be an exaptation for antiparasite defences and thus plays an important role in the host-parasite arms race.

Impact of nest sanitation on the immune system of parents and nestlings in a passerine bird

“…Exposure is likely to vary depending on species-specific sanitation practices and behaviours, as well as factors such as nest type and nest reuse (Brandl et al, 2014;Godard et al, 2007;Singleton and Harper, 1998). Bird species differ significantly in the level of nest sanitation: in some species, parents actively remove excrement from the nest; in others, young will defecate over the side of the nest; and in many species, excrement accumulates over the course of the breeding attempt (as reviewed by Guigueno and Sealy, 2012). The natural variation in nest hygiene across and within species can be attributed to interspecific differences in selection pressures such as predation risk.…”

The role of egg-nest contrast in the rejection of brood parasitic eggs

“…Hosts' acceptance thresholds also vary according to experience, even within a single clutch (Hauber et al, 2006). Hosts can respond to differences in eggshell background color (Avilés et al, 2005(Avilés et al, , 2010Honza et al, 2007;Honza and Polačiková, 2008;Moskát et al, 2008;Bán et al, 2013;Croston and Hauber, 2014a), maculation pattern (Lawes and Kirkman, 1996;Lahti and Lahti, 2002;López-de-Hierro and MorenoRueda, 2010;Spottiswoode and Stevens, 2010), egg brightness (Lahti, 2006;Gloag et al, 2014), egg size (Rothstein, 1982;Marchetti, 2000) and egg shape (Guigueno and Sealy, 2012) when discriminating their own from foreign eggs.…”

Full Issue

“…A recent study of Red-whiskered Bulbul Pycnonotus jocosus reached the same conclusion after experimentally discovering that the timing and mass of faecal sacs was linked to feeding frequency (Quan et al 2015). This suggests that the benefits of nest sanitation (Petit et al 1989, Guigueno & Sealy 2012, Ibáñez-Álamo et al 2016)-especially given the visual conspicuousness of faecal sacs-may oppose selection for reduced auditory exposure to predators (Tarwater et al 2009).…”