Multiple parasitism reduces egg rejection in the host (Acrocephalus arundinaceus) of a mimetic avian brood parasite (Cuculus canorus).

2019 ◽  
Vol 133 (3) ◽  
pp. 351-358 ◽  
Author(s):  
Thomas J. Manna ◽  
Csaba Moskát ◽  
Lainga Tong ◽  
Miklós Bán ◽  
Zachary Aidala ◽  
...  
Keyword(s):  
Acrocephalus Arundinaceus ◽  
Egg Rejection ◽  
Brood Parasite ◽  
Cuculus Canorus

scholarly journals Fast and furious: host aggression modulates behaviour of brood parasites

2020 ◽  
Author(s):  
Václav Jelínek ◽  
Michal Šulc ◽  
Gabriela Štětková ◽  
Marcel Honza
Keyword(s):  
Brood Parasitism ◽  
Egg Laying ◽  
Nest Defence ◽  
Great Reed Warbler ◽  
Acrocephalus Arundinaceus ◽  
Brood Parasite ◽  
Cuculus Canorus ◽  
Common Cuckoo ◽  
Brood Parasites ◽  
The Common

ABSTRACTAvian brood parasites pose a serious threat for hosts, substantially reducing their fitness which selects for the evolution of host defences. A classic example of a host frontline defence is mobbing which frequently includes contact attacking of brood parasites. Here, we investigated how the nest defence of a very aggressive great reed warbler (Acrocephalus arundinaceus) host influences the speed of egg-laying and egg-removing behaviour of its brood parasite – the common cuckoo (Cuculus canorus). We video-recorded 168 brood parasitic events at 102 active host nests and found that cuckoos avoided host mobbing in only 62% of cases. If hosts spotted the cuckoo at their nests, they almost always attacked it (in 91 of 104 cases), however, such attacks only rarely and temporarily prevented cuckoos from parasitizing (11 additional cases). When attacked, cuckoos parasitized host nests significantly faster and left them immediately. However, when not attacked, cuckoos frequently stayed at or near the nest suggesting that host aggression, rather than the risk of being spotted, influences the speed of brood parasitism in this species. Further, we found that cuckoos performed egg-removing behaviour in all parasitic events without regard to host aggression. As a result, cuckoos removed at least one egg during all brood parasitism events except those when an egg slipped from their beaks and fell back into the nest (in 9 of 73 cases). This indicates that egg-removing behaviour is not costly for the common cuckoo and is an essential part of its parasitism strategy, widening understanding of this currently unexplained behaviour.

scholarly journals Experimental shift in hosts' acceptance threshold of inaccurate-mimic brood parasite eggs

2006 ◽  
Vol 2 (2) ◽  
pp. 177-180 ◽  
Author(s):  
Márk E Hauber ◽  
Csaba Moskát ◽  
Miklós Bán
Keyword(s):  
Adaptive Modulation ◽  
Critical Role ◽  
Egg Laying ◽  
Acrocephalus Arundinaceus ◽  
Brood Parasite ◽  
Cuculus Canorus ◽  
Common Cuckoo ◽  
Acceptance Threshold ◽  
Resistance Strategies ◽  
The Common

Hosts are expected to evolve resistance strategies that efficiently detect and resist exposure to virulent parasites and pathogens. When recognition is not error-proof, the acceptance threshold used by hosts to recognize parasites should be context dependent and become more restrictive with increasing predictability of parasitism. Here, we demonstrate that decisions of great reed warblers Acrocephalus arundinaceus to reject parasitism by the common cuckoo Cuculus canorus vary adaptively within a single egg-laying bout. Hosts typically accept one of their own eggs with experimentally added spots and the background colour left visible. In contrast, hosts reject such spotted eggs when individuals had been previously exposed to and rejected one of their own eggs whose background colour had been entirely masked. These results support patterns of adaptive modulation of antiparasitic strategies through shifts in the acceptance threshold of hosts and suggest a critical role for experience in the discrimination decisions between inaccurate-mimic parasite eggs and hosts' own eggs.

Environmentally driven escalation of host egg rejection decimates success of an avian brood parasite

2020 ◽  
Vol 31 (6) ◽  
pp. 1316-1325 ◽  
Author(s):  
John M Eadie ◽  
Bruce E Lyon
Keyword(s):  
Large Scale ◽  
Ecological Factors ◽  
Water Levels ◽  
Environmental Drivers ◽  
Egg Rejection ◽  
Vital Rates ◽  
Brood Parasite ◽  
Parasitic Lifestyle ◽  
Almost All ◽  
Rejection Rates

Abstract The black-headed duck (Heteronetta atricapilla) of South America is the only known avian obligate brood parasite with precocial offspring. In Argentina, it relies on two species of coots as primary hosts, which typically reject 35–65% of duck eggs. We show that environmentally driven increases in host egg rejection behavior lead to substantial reductions in the reproductive success of the brood parasite. Episodes of flooding and vegetation loss caused dramatic shifts in host egg-rejection behavior, resulting in rejection (85–95%) of almost all duck eggs. Coots respond to fluctuating water levels by building up their nest, raising their own eggs but leaving duck eggs behind. Coots can apparently recognize parasitic duck eggs, but large-scale rejection is triggered only when hosts must actively make a choice. We use a simple population model to illustrate the unique demographic challenges that black-headed ducks face with their parasitic lifestyle and to explore the potential impact of environmentally induced escalation of egg rejection. Using the best available estimates for key vital rates, we show that obligate parasitism may provide a demographically precarious existence for black-headed ducks, even under benign environmental conditions. Environmentally mediated increases in egg rejection rates by hosts could impact significantly the viability of this enigmatic species of brood parasitic duck. Our results demonstrate that egg rejection rates are not fixed properties of host populations or individuals but are strongly influenced by social and ecological factors. Shifts in these environmental drivers could have important and unforeseen demographic consequences for brood parasites.

Gut microbiota in a host–brood parasite system: insights from common cuckoos raised by two warbler species

2020 ◽  
Vol 96 (9) ◽  
Author(s):  
Lucie Schmiedová ◽  
Jakub Kreisinger ◽  
Milica Požgayová ◽  
Marcel Honza ◽  
Jean-François Martin ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Gut Microbiota ◽  
Acrocephalus Arundinaceus ◽  
Brood Parasite ◽  
Bacterial Strains ◽  
Factors Affecting ◽  
The Common ◽  
Animal Hosts ◽  
Bacterial Sources ◽  
Selection Of

ABSTRACT An animal's gut microbiota (GM) is shaped by a range of environmental factors affecting the bacterial sources invading the host. At the same time, animal hosts are equipped with intrinsic mechanisms enabling regulation of GM. However, there is limited knowledge on the relative importance of these forces. To assess the significance of host-intrinsic vs environmental factors, we studied GM in nestlings of an obligate brood parasite, the common cuckoo (Cuculus canorus), raised by two foster species, great reed warblers (Acrocephalus arundinaceus) and Eurasian reed warblers (A. scirpaceus), and compared these with GM of the fosterers’ own nestlings. We show that fecal GM varied between cuckoo and warbler nestlings when accounting for the effect of foster/parent species, highlighting the importance of host-intrinsic regulatory mechanisms. In addition to feces, cuckoos also expel a deterrent secretion, which provides protection against olfactory predators. We observed an increased abundance of bacterial genera capable of producing repulsive volatile molecules in the deterrent secretion. Consequently, our results support the hypothesis that microbiota play a role in this antipredator mechanism. Interestingly, fosterer/parent identity affected only cuckoo deterrent secretion and warbler feces microbiota, but not that of cuckoo feces, suggesting a strong selection of bacterial strains in the GM by cuckoo nestlings.

scholarly journals Endocrine regulation of egg rejection in an avian brood parasite host

2020 ◽  
Vol 16 (6) ◽  
pp. 20200225 ◽  
Author(s):  
Mikus Abolins-Abols ◽  
Mark E. Hauber
Keyword(s):  
Stress Response ◽  
Stress Physiology ◽  
Endocrine Regulation ◽  
Egg Rejection ◽  
Brood Parasite ◽  
Potential Mechanism ◽  
Turdus Migratorius ◽  
American Robins ◽  
Defence Behaviour ◽  
Behavioural Adaptations

Parasite–host coevolution can lead to novel behavioural adaptations in hosts to resist parasitism. In avian obligate brood parasite and host systems, many host species have evolved diverse cognitive and behavioural traits to recognize and reject parasitic eggs. Our understanding of the evolution and ecology of these defences hinges on identifying the mechanisms that regulate them. We hypothesized that corticosterone, a hormone linked to stress response, vigilance and the suppression of parental behaviour, stimulates the rejection of foreign eggs by brood parasite hosts. We experimentally reduced circulating glucocorticoid levels with mitotane injections in American robins Turdus migratorius and found that the mitotane-treated birds rejected foreign eggs at a lower frequency compared to the sham-treated subjects. This is the first study to causally identify a potential mechanism of a widespread defence behaviour, and it is consistent with egg rejection being mediated by stress physiology.

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