Nest Predation and the Evolution of Conspecific Brood Parasitism: From Risk Spreading to Risk Assessment

Abstract

Conspecific brood parasitism (CBP) is a taxonomically widespread reproductive tactic. One of the earliest hypotheses put forward to explain the evolution of CBP was "risk spreading"; that is, by laying eggs in more than one nest, parasites may increase the likelihood that at least one offspring will survive to independence. However, the risk spreading hypothesis, based on the assumptions of random nest predation and random selection of target nests by parasites, was theoretically refuted soon after its appearance. New results from the common goldeneye (Bucephala clangula) have revealed that nests are not predated at random and that parasites preferentially lay in safe nests. By taking into account these findings and by modifying accordingly the basic assumptions of the earlier model that refuted the risk spreading hypothesis, we built a model to address the role of nest predation in the evolution of CBP. Model simulations revealed that the selective advantage of parasitic laying, related to nest predation, is much higher than previously thought. Furthermore, the invasion probability of parasitic tactic when initially rare was reasonably high within our model framework. We show that the use of risk assessing, instead of random risk spreading, makes parasitic laying evolutionarily advantageous.

Analysis of extra‐pair paternity and conspecific brood parasitism in mallards Anas platyrhynchos using non‐invasive techniques

“…But, we can not exclude the possibility that our sampling strategy biased our estimates of CBP rates compared with the true population mean, due to nest predation. Specifically, CBP rates can be over‐estimated if parasitic females prefer nests that are less likely to be detected by predators (Pöysä 2003, Pöysä and Pesonen 2007). Conversely, if the detection of clutches by parasitic females relies on similar clues that are used by nest predators, CBP rates will be under‐estimated.…”

“…For EPP in particular, the ability of males to monopolize a social mate can vary (Neuhauser et al 2001, Albrecht et al 2007). Similarly, a parasitic female prefers safer nest sites, nests of high‐quality hosts (Pöysä 2003, Pöysä and Pesonen 2007), or, simply, nests that are easier to detect (Semel et al 1988), resulting in the skewed distribution of CBP events throughout nests.…”

Nest Sanitation as the Evolutionary Background for Egg Ejection Behaviour and the Role of Motivation for Object Removal

“…There are obvious advantages for the parasites, namely they save energy by not paying for rearing their young, and consequently have free energy to produce more eggs [4], [5] and by distributing eggs to different host nests they spread the risk for their offspring, as the likelihood that at least one offspring survives, increases [6]. In contrast, brood parasitism is detrimental for the host and its own chicks and, in the best scenario, the host simply wastes energy feeding unrelated offspring [2], [3].…”

Age-specific nest-site preference and success in eiders

“…A corollary prediction is that a decline in breeder residual reproductive value, through increased mortality and/or decreased fecundity, should favour the choice of concealed nests, increasing the survival prospects of current oVspring (Öst et al 2008a) at the potential expense of adult life span. Alternatively, familiarity with local predator hunting strategies (Brown et al 2008), ability to assess predation risk (Pöysä and Pesonen 2007) or to escape predation, may contribute to age-related improvement in selecting nest sites (Pärt 1995). Experienced breeders may be able to select concealed nests at no apparent cost to their life expectancy, provided that they are capable of, e.g.…”