Grasp-ejection in two small ejecters of cowbird eggs: a test of bill-size constraints and the evolutionary equilibrium hypothesis

Underwood, Todd J.; Sealy, Spencer G.

doi:10.1016/j.anbehav.2005.06.004

Cited by 34 publications

(50 citation statements)

References 32 publications

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“…The mode of rejection and the extent and magnitude of costs have been shown to depend on host bill-size with larger-billed species rejecting by grasp ejection experiencing no or very few costs and smallerbilled ones suffering progressively greater costs as bills become smaller (Davies and Brooke, 1989a;Moksnes et al, 1991a;Antonov et al, 2006a). However, this relationship is not straightforward because there are documented cases where larger-billed hosts suffer larger costs than much smaller hosts (Underwood and Sealy, 2006).…”

Section: Puncture Resistance Hypothesismentioning

confidence: 88%

“…However, there is a twist to the cowbird story as the cowbird chick has been experimentally shown to extract more parental feedings from hosts and grow better when raised together with some host chicks in at least one medium-sized host species (Kilner et al, 2004). Overall, in the majority of these cases, the hosts of non-evicting parasites seem to do better by abandoning the parasitized clutch and renesting, and rejection costs seem of little importance in making hosts accept (Lorenzana and Sealy, 2001;Underwood and Sealy, 2006). Thus, the widespread acceptance of cowbird eggs, or the predominance of nest desertion as the rejection mode by many small hosts, is considered to be better explained by evolutionary lag (Underwood and Sealy, 2006).…”

Section: Puncture Resistance Hypothesismentioning

confidence: 99%

“…selective removal of the parasitic egg from the nest by the host while saving the rest of the clutch (Rothstein, 1975;Lorenzana and Sealy, 2001). However, many small host species are unable to grasp the parasitic egg in their mandibles due to constraints imposed from small bills or particular bill shapes (Rothstein 1975;Moksnes et al, 1991a; but see Underwood and Sealy, 2006). Such hosts have to first puncture the parasitic egg to be able to take it in the bill and carry it away from the nest (Rohwer and Spaw, 1988;Moksnes et al, 1991aMoksnes et al, , 1994.…”

Section: Puncture Resistance Hypothesismentioning

confidence: 99%

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Why do brood parasitic birds lay strong-shelled eggs?

Antonov¹,

Stokke²,

Fossøy³

et al. 2012

CHINESE BIRDS

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Brood parasitic birds constitute a model system for the study of coevolution. Such parasites are unique by having evolved unusually thick eggshells for their body size. Thick eggshells have been hypothesized to evolve as 1) a means of preventing damage to parasite eggs when the brood parasite lays its egg at a distance from the host clutch (the laying damage hypothesis); 2) a consequence of host puncture ejection (the puncture resistance hypothesis); 3) a means for the brood parasite to allocate calcium to development of a disproportionately large skeleto-muscular system in evicting parasite chicks (the chick vigour hypothesis); or 4) a means of protecting the cuckoo embryo from microorganisms in the nest of the host (the anti-bacterial protection hypothesis). Here we review the literature studying the evolutionary mechanisms promoting thick eggshells in avian brood parasites, and provide proposals for future studies to test their validity. Available data are insufficient to rigorously test exclusive predictions and assumptions of these not necessarily exclusive hypotheses, although the laying damage and the puncture resistance hypotheses seem to currently be the most well supported alternatives. We discuss how quantification of rejection modes (grasp ejection, puncture ejection and desertion) may disclose the validity of the puncture resistance hypothesis, and finally we provide perspectives for future research on testing this specific hypothesis.

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Section: Puncture Resistance Hypothesismentioning

confidence: 88%

Section: Puncture Resistance Hypothesismentioning

confidence: 99%

Section: Puncture Resistance Hypothesismentioning

confidence: 99%

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Why do brood parasitic birds lay strong-shelled eggs?

Antonov¹,

Stokke²,

Fossøy³

et al. 2012

CHINESE BIRDS

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“…Bill breadth was measured as the distance between the commissural points. Grasp index is the product of bill length and bill breadth [23][24][25][26]. I also The three numbers are 1 ¼ southern African subspecies of Jacobin cuckoo and Cape bulbul and 2 and 3 ¼ Indian Jacobin cuckoo subspecies with the two main babbler host species.…”

Section: Methodsmentioning

confidence: 99%

Brood parasitism selects for no defence in a cuckoo host

Krüger

2011

Proc. R. Soc. B.

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In coevolutionary arms races, like between cuckoos and their hosts, it is easy to understand why the host is under selection favouring anti-parasitism behaviour, such as egg rejection, which can lead to parasites evolving remarkable adaptations to 'trick' their host, such as mimetic eggs. But what about cases where the cuckoo egg is not mimetic and where the host does not act against it? Classically, such apparently non-adaptive behaviour is put down to evolutionary lag: given enough time, egg mimicry and parasite avoidance strategies will evolve. An alternative is that absence of egg mimicry and of anti-parasite behaviour is stable. Such stability is at first sight highly paradoxical. I show, using both field and experimental data to parametrize a simulation model, that the absence of defence behaviour by Cape bulbuls (Pycnonotus capensis) against parasitic eggs of the Jacobin cuckoo (Clamator jacobinus) is optimal behaviour. The cuckoo has evolved massive eggs (double the size of bulbul eggs) with thick shells, making it very hard or impossible for the host to eject the cuckoo egg. The host could still avoid brood parasitism by nest desertion. However, higher predation and parasitism risks later in the season makes desertion more costly than accepting the cuckoo egg, a strategy aided by the fact that many cuckoo eggs are incorrectly timed, so do not hatch in time and hence do not reduce host fitness to zero. Selection will therefore prevent the continuation of any coevolutionary arms race. Non-mimetic eggs and absence of defence strategies against cuckoo eggs will be the stable, if at first sight paradoxical, result.

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“…In these species, it is unclear whether this reflects variation among individuals in cognitive aspects of recognition or variation in the recognition cues or social environment that an individual happens to encounter (Davies et al, 1996;Rothstein, 1982). Understanding why hosts vary in defenses against parasitism remains an important area of inquiry, and a number of factors have been identified to explain why such traits are lacking in some species or individuals within species (Davies, 1999;Kruger, 2011;Moskat and Hauber, 2007;Røskaft et al, 2006;Rothstein, 1990;Underwood and Sealy, 2006). Brood parasitism within species also occurs in birds, having been documented in over 200 species (Andersson, 1984;Lyon and Eadie, 2008;Yom-Tov, 1980.…”

mentioning

confidence: 99%