Impact of brood parasitism and predation on nest survival of the fan‐tailed gerygone in New Caledonia

AbstractAlthough area and isolation effects on avian communities in highly fragmented landscapes are well known, importance of landscape composition in more forested landscapes remains poorly understood. We determined if the type (agriculture and silviculture) and extent (percentage within 1 km radius) of disturbance within forested landscapes influenced avian nesting success, and then examined if differences in stand-level habitat structure, nest-patch microhabitat, distance of nests to habitat edges, brood parasitism rates, and nest-predator abundance were potential underlying mechanisms of observed associations between landscape composition and nesting success. We monitored active songbird nests (n = 341), surveyed Brown-headed Cowbirds (Molothrus ater) and nest predators, and measured stand-level and nest-patch microhabitat from May–July 1998 and 1999. Each of 10 study sites was located within contiguous mature forest in central Pennsylvania and contained either agricultural or silvicultural disturbances (n = 5 each). Sites of the two landscape types had similar ranges of disturbance within 1 km (21–55% for agriculture, 18–51% for silviculture). Daily nest survival for all species combined (94.0 ± 0.55 in agriculture and 96.9 ± 0.87 in silviculture) and midstory-canopy nesters (93.8 ± 0.97 in agriculture and 97.4 ± 0.75 in silviculture) were greater within forested landscapes disturbed by silviculture than by agriculture, but rates did not significantly differ between landscapes for ground nesters (92.2 ± 1.32 in agriculture and 94.6 ± 1.63 in silviculture) or understory nesters (95.4 ± 1.60 in agriculture and 95.0 ± 1.47 in silviculture). Nest survival was not significantly associated with disturbance extent. Rates of brood parasitism were low, with only 11% of nests containing cowbird eggs or young. Neither nest fate nor differences in daily nest survival between the two landscape types were explained by variation in brood parasitism rates, stand-level or nest-patch habitat characteristics, or distance of nests to edges. Instead, the lower nest success within forested landscapes disturbed by agriculture was best explained by greater abundances of some avian and small mammalian predators (American Crow [Corvus brachyrhynchos] and squirrels) in those landscapes in one or both years. Results suggest that landscape composition within forested landscapes significantly influences avian nesting success by altering interactions between nest predators and nesting birds.

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Discrimination and ejection of eggs and nestlings by the fan-tailed gerygone from New Caledonia

Current Zoology ◽

10.1093/cz/zoab066 ◽

2021 ◽

Author(s):

Alfredo Attisano ◽

Nozomu J Sato ◽

Keita Tanaka ◽

Yuji Okahisa ◽

Keisuke Ueda ◽

...

Keyword(s):

Breeding Season ◽

Brood Parasitism ◽

Visual Cues ◽

Size Range ◽

New Caledonia ◽

Host Defence ◽

Combined Approach ◽

Rare Type ◽

Egg Ejection ◽

Nestling Period

Abstract Nestling ejection is a rare type of host defence against brood parasitism compared to egg ejection. Theoretically, host defences at both egg and nestling stages could be based on similar underlying discrimination mechanisms but, due to the rarity of nestling ejector hosts, few studies have actually tested this hypothesis. We investigated egg and nestling discrimination by the fan-tailed gerygone Gerygone flavolateralis, a host that seemingly accepts non-mimetic eggs of its parasite, the shining bronze-cuckoo Chalcites lucidus, but ejects mimetic parasite nestlings. We introduced artificial eggs or nestlings and foreign gerygone nestlings in gerygone nests and compared begging calls of parasite and host nestlings. We found that the gerygone ejected artificial eggs only if their size was smaller than the parasite or host eggs. Ejection of artificial nestlings did not depend on whether their colour matched that of the brood. The frequency of ejection increased during the course of the breeding season mirroring the increase in ejection frequency of parasite nestlings by the host. Cross-fostered gerygone nestlings were frequently ejected when lacking natal down and when introduced in the nest before hatching of the foster brood, but only occasionally when they did not match the colour of the foster brood. Begging calls differed significantly between parasite and host nestlings throughout the nestling period. Our results suggest that the fan-tailed gerygone accepts eggs within the size range of gerygone or cuckoo eggs and that nestling discrimination is based on auditory and visual cues other than skin colour. This highlights the importance of using a combined approach to study discrimination mechanisms of hosts.

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Patch size and edge proximity are useful predictors of brood parasitism but not nest survival of grassland birds

Ecological Applications ◽

10.1890/12-1101.1 ◽

2013 ◽

Vol 23 (4) ◽

pp. 879-887 ◽

Cited By ~ 20

Author(s):

Thomas J. Benson ◽

Scott J. Chiavacci ◽

Michael P. Ward

Keyword(s):

Brood Parasitism ◽

Patch Size ◽

Nest Survival ◽

Grassland Birds

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Impact of Brood Parasitism on Nest Survival Parameters and Seasonal Fecundity of Six Songbird Species in Southeastern Old-Field Habitat

The Condor ◽

10.1093/condor/102.4.946 ◽

2000 ◽

Vol 102 (4) ◽

pp. 946-950 ◽

Cited By ~ 6

Author(s):

Maria A. Whitehead ◽

Sara H. Schweitzer ◽

William Post

Keyword(s):

South Carolina ◽

Clutch Size ◽

Host Species ◽

Brood Parasitism ◽

Nest Survival ◽

Brood Reduction ◽

Hatching Rate ◽

Old Field ◽

Parasitism Rates ◽

Seasonal Fecundity

Abstract We monitored 259 nests of six Brown-headed Cowbird (Molothrus ater) hosts within old-field habitat on James Island, South Carolina during the 1997 and 1998 breeding seasons to determine the effect of parasitism on three nest-survival parameters (clutch size, hatching rate, and number of fledglings). We determined daily predation and parasitism rates, and probability of nest abandonment after parasitism to derive an estimate of seasonal fecundity. Clutch size of parasitized nests was reduced in four host species. Brood parasitism did not affect hatching rate in any species, and reduced the number of fledglings from only Blue Grosbeak (Guiraca caerulea) nests. Despite brood reduction during the nesting cycle, cowbird parasitism had little impact on seasonal fecundity of these host species because of low parasitism intensity, double-brooding behavior, and hosts' ability to raise their own young with cowbird young.

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