Do first-time breeding females imprint on their own eggs?

Abstract

The egg-recognition processes underlying egg rejection are assumed to be based on an imprinting-like process (a female learning the aspect of her own eggs during her first breeding attempt). The imprinting-like process and the misimprinting costs have been the objective of many theoretical models and frequently have a leading role in papers published on brood parasitism; however, an experiment has never been undertaken to test the existence of this imprinting-like process by manipulating egg appearance in first-time breeding females. Here, we present the first such experimental study using the house sparrow (Passer domesticus), which is a conspecific brood parasite and which has a good ability to reject conspecific eggs, as a model species. We found that contrary to what the hypothesis predicts first-time breeding females did not reject their own eggs in their second breeding attempt. This lack of response against unmanipulated eggs could indicate that females have an innate preference for their own eggs. However, in a second experimental group in which first-time breeding females were allowed to learn the aspect of their (unmanipulated) own eggs, none ejected manipulated eggs during their second clutch either-a finding that does not support the idea of recognition templates being inherited, but instead suggests that recognition templates could be acquired again at each new breeding attempt. Our results demonstrate that it is likely that egg discrimination is not influenced by egg appearance in the first breeding attempt.

Cuckoo Hosts Shift From Accepting to Rejecting Parasitic Eggs Across Their Lifetime

“…First‐time breeder magpies cannot learn to recognize cuckoo parasitism and reject eggs (see however Soler ), unless they learn the appearance of their own eggs by imprinting on the first one or two eggs they lay in their first clutch (Rothstein , ). The existence of a prolonged learning process based on observation of their own eggs in which recognition templates could also be updated at each subsequent breeding attempt (Lotem et al ; Lahti and Lahti ; Moskat and Hauber ; Soler et al ) may not explain changes from acceptance to rejection in magpies. If females had incorporated models eggs within their templates they would be less prone to modify rejection behavior.…”

Brood parasites lay eggs matching the appearance of host clutches

“…A number of studies have been published on the mechanisms of own egg recognition in cuckoo hosts [76][77][78][79][80][81][82][83] and some of them suggest that birds possess an internal template of their own eggs [81][82][83]. So, one may expect that cuckoos may exhibit such abilities as well.…”

Great Spotted Cuckoo Fledglings Often Receive Feedings from Other Magpie Adults than Their Foster Parents: Which Magpies Accept to Feed Foreign Cuckoo Fledglings?

“…caring only for cuckoo fledglings) is a main factor determining the propensity to feed foreign cuckoo fledglings implies that recognition templates (i.e. internal representation of the appearance of parasitic chicks [83] ) are not inherited or learned during the female's first breeding attempt as traditional theory assumed [52] , [74] , [75] , [84] – [88] but that they are acquired again at each new breeding attempt, as has been suggested in several more recent studies [89] , [90] and has recently experimentally been demonstrated [91] .…”