Behavioural Responses of Potential Hosts Towards Artificial Cuckoo Eggs and Dummies

Cuckoos, cowbirds and hosts: adaptations, trade-offs and constraints

“…The key counter-adaptation of hosts before a parasitic egg is laid is aggression towards the parasitic female (Moksnes et al 1991a;Røskaft et al 2002a). Indeed, unsuitable host species have been shown to react less aggressively towards a Common Cuckoo dummy than suitable host species (Moksnes et al 1991a) and hosts of Brown-headed Cowbirds show increasing aggression with increasing parasitism rate (Robertson & Norman 1976).…”

“…Indeed, unsuitable host species have been shown to react less aggressively towards a Common Cuckoo dummy than suitable host species (Moksnes et al 1991a) and hosts of Brown-headed Cowbirds show increasing aggression with increasing parasitism rate (Robertson & Norman 1976). This aggressive behaviour can be a specific response to parasitism: the response to predators can be similar (Grim 2005) or significantly different (Duckworth 1991;Davies et al 2003).…”

Geographic variation in egg ejection rate by great tits across 2 continents

“…Host resistance to parasitism is often consistent among populations (e.g., Grim et al 2011). Thus, Moksnes et al (1991), Moksnes and Røskaft (1995), and Davies (2000) classified most hole-nesting bird species as "unsuitable" for cuckoo parasitism, with the sole exception of the hole-nesting redstart Phoenicurus phoenicurus that is a common cuckoo host, apparently because cavities used by this species generally have large entrances that allow the cuckoo female to enter the nest and the cuckoo chick to fledge (von Haartman 1981;Grim et al 2009). In contrast, a recent comparative analysis by Medina and Langmore (2015) showed that nest type was not predictive of egg rejection rates in hosts of brood parasites, and even tits and other hole-nesters often use natural cavities with large entrances (van Balen et al 1982) that should readily allow a cuckoo to lay its egg in such nests.…”

Geographic distribution of the anti-parasite trait “slave rebellion”

“…In the wellstudied avian systems (Kruger 2007) as well as in social insects (Hare and Alloway 2001;Fischer-Blass et al 2006;Foitzik et al 2009) severe fitness costs for the host have been demonstrated, resulting in strong selection pressures on the host species. In response, they have developed defence mechanisms either to avoid parasitic exploitation (Alloway 1990; 45 50 55 60 Moksnes et al 1991;Roskaft et al 2002) or to reduce its costs once parasitized (Langmore et al 2003;Kruger 2007;Achenbach and Foitzik 2009). …”

“…These defence mechanisms often involve mobbing of parasites as soon as they are spotted (Moksnes et al 1991;Roskaft et al 2002). In addition, various parasitized species have developed the ability to recognize parasite eggs by their size or colour.…”