Search results for "Brood parasitism"

Avian brood parasitism in a Mediterranean region. hosts and habitat preferences of Common Cuckoos Cuculus canorus

2009

Capsule Cuckoos in Italy support the ‘host preference’ hypothesis. Aims To identify the species parasitized in a Mediterranean area, in Italy; to quantify the frequency of parasitism on each host species; and to determine whether some species and/or habitat types are parasitized more than expected from a homogeneous distribution. Methods Nest records dating from 1865 were compiled from literature, nest card programmes, and personal communication with ornithologists working in the region. Comparisons of parasitism frequencies were made among and within habitats for all cuckoo hosts. Results The most frequently parasitized hosts were Great Reed Warbler, European Robin, Marsh Warbler, Redstart…

Use of social over personal information enhances nest defense against avian brood parasitism

2011

Interactions with conspecifics influence the behavioral repertoire of an organism, as they apply to foraging techniques, song acquisition, habitat selection, and mate choice. Few workers have studied the role of social interactions in molding defense responses, especially the defense of the nest. We tested the effect of social interaction on nest defense of the reed warbler (Acrocephalus scirpaceus), one of the main hosts of the brood-parasitic common cuckoo (Cuculus canorus) in Europe. This parasite reduces its host’s breeding success; therefore, any response that prevents successful parasitism should be selected. Because of their high nesting density and consistent cuckoo-specific respons…

Enemy recognition of Reed Warblers (Acrocephalus scirpaceus): threats and reproductive value act independently in nest defence modulation

2010

Organisms should respond more aggressively towards species perceived as a danger to their offspring, but intensity of defence may be gauged by the value of current offspring weighed against the value of future reproductive opportunities. We tested whether defensive responses of nesting reed warblers (Acrocephalus scirpaceus) are the result of an interaction effect between the type of stimulus confronted and the value of the warbler’s nesting attempt. We quantified the ability of reed warblers to discriminate among brood parasites, nestling predators and non-threatening species at different stages of the breeding cycle. We also determined whether variables that influence the value of offspri…

Old versus new world: adaptive significance of nest defence in two brood parasitism systems

2011

Reed Warbler Hosts Do Not Fine-Tune Mobbing Defenses During the Breeding Season, Even When Cuckoos Are Rare

2021

Hosts of brood parasitic cuckoos often employ mobbing attacks to defend their nests and, when mobbing is costly, hosts are predicted to adjust their mobbing to match parasitism risk. While evidence exists for fine-tuned plasticity, it remains unclear why mobbing does not track larger seasonal changes in parasitism risk. Here we test a possible explanation from parental investment theory: parents should defend their current brood more intensively as the opportunity to replace it declines (re-nesting potential), and therefore “counteract” any apparent seasonal decline to match parasitism risk. We take advantage of mobbing experiments conducted at two sites where reed warblers (Acrocephalus sc…

Avian brood parasitism in Italy: Another perspective

2020

We present a quantitative analysis of the data reported in the only published review of parasitism frequency on hosts of Common Cuckoo Cuculus canorus in a Mediterranean area. We first eliminated a bias potentially introduced by the method by which data were recorded. Of the initial potential 70 species parasitized in Italy, only 44 were confirmed as host species, of which only 10 species had more than 10% of their total nests parasitized. We highlighted differential parasitism on host species according to geographic area, but the analysis suggested results were strongly biased because nest location was generally not reported and the number of records steeply decreased from North to South.

Avian brood parasitism in the new and old worlds

Evolutionary consequences of social transmission in avian brood parasitism systems

Obligate brood parasites lay all of their eggs in nests of other species, leaving the burden of parental care entirely to the hosts. As a consequence of being parasitized, hosts’ reproductive success is often reduced. This strategy has triggered a coevolutionary dynamic involving behavioural, physiological and morphological adaptations and counter-adaptations from the two players, whose conflicting functions are to successfully parasitize a nest, and prevent or reduce the negative effects of parasitism. In parasite systems studied in the New and Old worlds, warbler hosts exhibited different degrees of learning antiparasite defences from conspecifics. By quantifying strength and direction of…

Dazzled and confused? Habituation and sensitization in free-living Yellow Warblers

2004

Cowbird versus cuckoo hosts: a comparative study of learned nest defense

2005

One of the best example of coevolutionaru adaptations is that of the interactions between avian brood parasites and their hosts. Brood parasites lay their eggs in nests of other specieis and leave the job of caring for their young with the hosts. Hosts of brood parasites tend to suffer high reproductive costs as often they raise few of no young of their own, an effect of being parasitizes. For this reason, many hosts have evolved strategies that reduces the cost of parasitism.