Threat recognition and response in an avian brood-parasite host from New Caledonia

Abstract

Nest predation and avian brood parasitism are the main sources of nest failure in many passerine birds. Large predators threaten both brood and parents, whereas brood parasites pose only a danger to eggs or nestlings. The fan-tailed gerygone Gerygone flavolateralis from New Caledonia is subjected to high rates of nest predation by the New Caledonian crow Corvus moneduloides (responsible for about 20-40% of predation) and moderate rates of brood parasitism by the shining bronze-cuckoo Chalcites lucidus (parasitising about 18% of nests), which also depredates nests that are too advanced for parasitism (13% of nests). To test if fan-tailed gerygones are able to discriminate predators from brood parasites, we presented 3 bird models at active gerygone nests: a brood parasite/small nest predator (shining bronze-cuckoo), a large nest predator (crow), and a small non-native bird (common chaffinch Fringilla coelebs), which is unknown to the gerygone, as a control. We assessed the response of adult gerygones to the presentation of each model by measuring the minimum approach distance, number of alarm calls, number of attacks, and time to first nest visit after the presentation (latency). Adult gerygones often attacked the cuckoo, approached but never attacked the chaffinch and always avoided the crow. Latency was shorter after an attack response and during brooding, but similar among models. We did not find any link between the cuckoo model presentation and later ejection of cuckoo nestlings. We conclude that adult fan-tailed gerygones discriminate between different models and respond accordingly to the level of threat, but do not show awareness of parasitism risk and increase of nestling ejection rates following exposure to the cuckoo model.

Polymorphism at the nestling stage and host‐specific mimicry in an Australasian cuckoo‐host arms race

“…All the hosts show some defences at the frontline stage. They react aggressively to adult shining bronze‐cuckoos approaching the nest (Briskie, 2007) as well as to stuffed specimens of shining bronze‐cuckoos presented at the nest (Attisano, Hlebowicz, et al, 2021; Medina & Langmore, 2016). The yellow‐rumped thornbill begins nesting in mid‐winter, substantially earlier than congeneric and sympatric insectivorous species and before migratory cuckoos arrive in their breeding ground, which is consistent with selection for earlier breeding to escape parasitism (Medina & Langmore, 2016).…”

“…All the hosts show some defences at the frontline stage. They react aggressively to adult shining bronze-cuckoos approaching the nest (Briskie, 2007) as well as to stuffed specimens of shining bronzecuckoos presented at the nest (Attisano, Hlebowicz, et al, 2021; F I G U R E 1 Eggs of shining bronze-cuckoos and their hosts from (a) Australia (cuckoo: olive green; yellow-rumped thornbill: unspotted white; photo by N. Langmore), (b) New Caledonia (cuckoo: dark brown; fan-tailed gerygone: whitish grey with brown speckles; photo by N. Sato) and (c) New Zealand (cuckoo: olive-green; grey warbler: whitish with brown speckles; photo by R. Thorogood). Medina & Langmore, 2016).…”

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

“… 45 Parasites may also prey on host eggs or chicks, 1 , 46 , 47 , 48 but studies on nest defense have demonstrated that parasites such as common cuckoos are recognized more often by hosts as cues of parasitism than predation. 1 , 49 , 50 , 51 , 52 Field observations suggest that the nest desertion behavior of hosts is primarily triggered by cues of parasitism, suggesting that nest desertion is an important adaptation mechanism of anti-parasitism behavior. 11 , 14 , 53 , 54 While previous studies have investigated host adaptation to nest desertion from different angles, they have rarely examined the impact of parental investment trade-offs on nest desertion at different stages of egg-laying.…”