Experimental enlargement of nest size does not increase risk of predation or brood parasitism in the Great Reed Warbler Acrocephalus arundinaceus

Abstract

We assessed whether nest size affects the probability of nest loss using dyads of large and small (large being twice the size of small) inactive Great Reed Warbler Acrocephalus arundinaceus nests placed at similar sites in Great Reed Warbler territories. Large nests were not predated significantly more frequently than small nests. Experimentally enlarged active Great Reed Warbler nests suffered non‐significantly higher predation compared with non‐manipulated control nests. Our experiments did not support the nest‐size hypothesis and suggested that nest size does not appear to be a factor affecting the risk of nest predation in this species. The probability of brood parasitism by the Common Cuckoo Cuculus canorus was also unaffected by experimental nest enlargement, supporting the commonly accepted hypothesis that the Common Cuckoo searches for suitable host nests by host activity during nest building rather than nest size.

Nest as an extended phenotype signal of female quality in the great reed warbler

“…Nevertheless, larger nests could suffer from a greater predation pressure (Møller , Biancucci and Martin ). Jelínek et al () tested this assumption in enlarged and control great reed warbler nests (the same as in the present article) and found only marginally non‐significant trend to higher predation of enlarged nests. Moreover, they used also dyads of large and small inactive great reed warbler nests and found no difference in predation rate between these two groups.…”

“…In magpies, the additional cost of large nests probably lies in greater probability of parasitism by great spotted cuckoos Clamator glandarius which preferably parasitize larger nests belonging to parents of better quality (Soler et al ). Our population of great reed warblers suffers from intensive parasitism by the common cuckoo, but a preference for larger nests was never found in this brood parasite neither in natural (Moskát and Honza , Jelínek et al ) nor in experimental conditions (Jelínek et al ). Nevertheless, larger nests could suffer from a greater predation pressure (Møller , Biancucci and Martin ).…”

“…For example at low predator densities nest predation could be affected rather by chance than by the inconspicuousness of a particular nest. This could be the reason of different results between studies López‐Iborra et al () and Jelínek et al () as the predation rate in the Spanish locality of López‐Iborra et al () was much higher because almost all nests (97%) were depredated during short 14‐d exposure while at the Czech site only 52% of nests were depredated within 30 d. Similarly, the evidence that larger active nests are more frequently depredated in other species is equivocal (Møller , Palomino et al , Antonov , Suárez et al ).…”

The evolution of postpairing male mate choice

“…However, because this color signal is expressed in the eggs, the female's potential mortality risk due to the expressed sexual signal should be lower than in species with ornamented females, from the perspective of detection by predators. Nest size has also been used as a form of signal by males in the Great Reed Warbler (Acrocephalus arundinaceus) (Jelínek et al 2016), and has been indicated to have no effect on nest predation or parasitism in the field (Jelínek et al 2015). Moreover, female feather carrying in the nest has also recently been proposed to affect male investment (Garcia-Navas et al 2015).…”

Nest Size Matters: Common Cuckoos Prefer to Parasitize Larger Nests of Oriental Reed Warblers

“…The optimal egg-laying strategy proposes that when there are su ciently many available nests at a given time, cuckoo females should prefer the nest made by the best quality hosts (Hauber 2001;Parejo and Avilés 2007;Jelínek et al 2014). In this scenario, cuckoos may select larger nests associated with increased tness because larger nests may indicate superior parenting ability (Soler et al 1998;de Neve et al 2004;Avilés et al 2009;Jelínek et al 2015). A study spanning eight consecutive years showed that large magpie (Pica pica) nests were more likely to be parasitized by great spotted cuckoos (Clamator glandarius) than smaller nests when cuckoos have a larger availability of host nests among which to choose.…”