Multiple parasitism in an evictor brood parasite: patterns revealed by long-term monitoring, continuous video recording, and genetic analyses

Abstract

In some populations of host of brood parasites, more than two parasite eggs may be laid in a single nest. This phenomenon is known as multiple parasitism, representing a cost to both host and parasite. In this study, we analysed a long-term dataset (2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019)(2020)(2021) focusing on multiple parasitism of the common cuckoo (Cuculus canorus) parasitizing the great reed warbler (Acrocephalus arundinaceus). Annual parasitism rate was on average 54.3% and varied between 5.8% and 92.2%, depending on the year. From 720 parasitized nests, double parasitism was recorded in 172 (23.9%) nests, triple in 51 (7.1%) nests, quadruple in 10 (1.3%) nests and, exceptionally, in the years of heavy parasitism (about 90%), quintuple parasitism was recorded in three (0.4%) nests. The rate of multiple parasitism ranged from 0% to 63% inter-annually and strongly correlated with parasitism rate and total number of parasite eggs found. Furthermore, the number of cuckoo eggs laid per one nest increased with decreasing daily availability of host nests that were at a suitable breeding stage for parasitism. Both genetic and egg phenotype analyses revealed that no cuckoo female laid more than one egg in the same host nest. Using data on long-term parasite-host interactions and from continuous video-recording, as well as progressive methods to assign parasite offspring thus helped us better understand various aspects of multiple parasitism in hosts heavily parasitized by an evictor brood parasite.

Nest desertion as an anti-parasitism strategy in hosts selects for late egg-laying behavior in cuckoos

“…The desertion rate of all experimentally parasitized nests was significantly lower than that of naturally parasitized nests during the early egg-laying stage, particularly in Group 2, which could be attributed to the different parasite encounters during the two processes, 7 , 11 , 28 , 65 as natural parasitism entails diverse cues, and the levels of exposure to these cues are different from those experienced during experimental conditions. For example, multiparasitised nests are more likely to be abandoned, 66 which could be related to multiple nest visits by cuckoos. We also observed that nests with four to five eggs were parasitized only after frequent parasitism attempts and host attacks, eventually leading to nest desertion.…”

Low incidence of cannibalism among brood parasitic cuckoo catfish embryos

“…), limit host offspring survival through competitive exclusion ( Soler 2017 ) or direct killing ( Honza et al 2007 ; Spottiswoode and Koorevaar 2012 ), in many cases resulting in the parasitic chick becoming the sole occupant of the nest. Concurrent (i.e., multiple or repeated) parasitism by two or more brood parasitic offspring within a single host clutch ( Gloag, Fiorini, et al 2012 ) is more commonly reported from brood parasites with a low impact on host offspring survival and condition ( Martínez et al 1998 ; Tuero et al 2007 ; Goguen et al 2011 ) than from virulent parasites ( Marton 2021 ; Honza et al 2022 ). This situation arises because high virulence is associated with increased competition for host resources, leading to poor survival prospects for the younger parasite ( Moskát and Honza 2002 ; Spottiswoode 2013 ).…”

Eggshell colour differences in a classic example of coevolved eggshell mimicry

“…The Acrocephalus warblers are among the most wellstudied cuckoo host genera [14,[23][24][25][26][27]]. As a prominent example of coevolutionary arms race [28], the warblercuckoo coevolution is often assumed to have had sufficient time to adapt both egg rejection and egg colour mimicry via coevolutionary arms races [14,29,30].…”