Importance of cooperation: How host nest defenses effectively prevent brood parasitism from the cuckoos

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Egg recognition and rejection are the most common and effective anti‐parasitic strategies against avian brood parasitism in terms of maintaining stability over time and plasticity in response to environmental cues. Conversely, parasites have evolved multiple counter‐adaptations to the anti‐parasitic defenses of hosts. Among them, the crypsis hypothesis suggests that eggs that appear more cryptic in color and are closely matched to the environment are helping to counter the egg recognition strategy of the host. In this study, we investigated whether the egg recognition ability of Oriental reed warblers (Acrocephalus orientalis), a common host of common cuckoos (Cuculus canorus), changed during different reproductive stages by using model egg experiments. The effect of the crypsis hypothesis on the egg recognition ability of the hosts was also investigated by controlling the color contrast between the inside of the experimental nests and the model eggs. The results showed that the Oriental reed warbler retained strong egg recognition abilities, which were similar to the incubation stage (GLMMs: F1,27 = 0.424, p = .521), even after entering the nestling stage and preferentially rejected model eggs with distinct contrasting colors (binomial test: Fisher's exact, p = .016). These results are consistent with the crypsis hypothesis. The present study suggests that the host retains a strong egg recognition ability even during the nestling stage and that cryptic‐colored eggs that are closely matched with the breeding nest environment help counter the host's egg recognition abilities and increase the chances of successful parasitism by cuckoos. However, the effectiveness of cryptic egg may be weaker than mimic egg in countering egg recognition and rejection by hosts with open‐cup nests.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Oriental reed warblers retain strong egg recognition abilities during the nestling stage

Ma,

Liu,

Pan

et al. 2024

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“…Another 10 cases of dead female cuckoos have been mostly found under GRW nests and in other avian host-parasite systems (reviewed by Šulc et al, 2020). For cuckoos, rapid egg-laying and flying away in due course can reduce the risk of attacks (Davies, 2000;Soler, 2017;Wang et al, 2023). In addition to avoiding attacks, quicker egg-laying can reduce host attention, thereby reducing the parasitic egg rejection risk (Davies, 2000).…”

Section: Discussionmentioning

confidence: 99%

Why cuckoos remove host eggs: Biting eggs facilitates faster parasitic egg‐laying

Wang,

Zhao,

Yan

et al. 2023

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Brood parasitism by cuckoos relies on manipulating hosts to raise their offspring and has evolved stunning adaptations to aid in their deception. The fact that cuckoos usually but not always, remove one or two host eggs while laying their eggs has been a longstanding focus of intensive research. However, the benefit of this behavior remains elusive. Moreover, the recently proposed help delivery hypothesis, predicting that egg removal by cuckoos may decrease the egg‐laying duration in the parasitism process caused by biting action, lacks experimental verification. Therefore, in this study, we examined the effects of egg removal/biting on the egg‐laying speed in the common cuckoo (Cuculus canorus) to experimentally test this hypothesis. We compared the duration of cuckoo egg‐laying in empty nests, nests with host eggs, and nests with artificial blue stick models to test whether cuckoos biting an egg/stick can significantly hasten the egg‐laying speed than no biting action. Our results showed that biting an egg or an object is associated with cuckoos laying approximately 37% faster than when they do not bite an egg or an object. This study provides the first experimental evidence for the help delivery hypothesis and demonstrates that when cuckoos bite eggs or other objects in the nest, they lay eggs more quickly and thereby avoid suffering the hosts' injurious attack.

“…How to cite this article: Wan, G., Zhao, H., Liu, X., Wang, L., & Liang, W. (2023). Predation of Daurian redstarts offspring in nest boxes by the Oriental magpie-robin and tree sparrow.…”

Section: Data Ava I L a B I L I T Y S Tat E M E N Tmentioning

confidence: 99%

“…Miniature video cameras are widely used to monitor the behavior of breeding birds. For example, the video recording showed the process of multiple host individuals of the Oriental reed warbler ( Acrocephalus orientalis ) mobbing and at tacking a female common cuckoo ( Cuculus canorus ) in the field (Wang et al, 2020 , 2023 ; Zhao et al, 2022 ). In addition, the video cameras are able to accurately capture the process of nest predation cases (Ball & Bayne, 2012 ).…”

Section: Introductionmentioning

confidence: 99%

Predation of Daurian redstarts offspring in nest boxes by the Oriental magpie‐robin and tree sparrow

Wan

Zhao

Liu

et al. 2023

Self Cite

Birds select suitable nest sites for breeding to ensure their own and offspring's survival; however, they inevitably suffer some potential predation risk. We studied the breeding ecology of Daurian redstarts ( Phoenicurus auroreus ) by providing nest boxes for their breeding from March to August of 2022. We recorded the predation of both Daurian redstarts eggs or nestlings by Oriental magpie‐robins ( Copsychus saularis ) and tree sparrow ( Passer montanus ). Oriental magpie‐robin were recorded attacking a feeding female adult and depredating nestlings. After the nestling predation event, the Daurian redstarts abandoned the nest. This video evidence provide a better understanding of the potential predators of cavity‐nesting birds.