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Nest defence against conspecific intruders in the Common Pochard Aythya ferina: natural observations and an experimental test

100%

Honza M., Pialkova R., Albrecht T., Neuzilova S.

Acta Ornithologica

2009

tom 44

nr 2

The reproductive behaviour of brood parasitic birds has been of long-standing interest to evolutionary biologists, but some key features of this breeding tactic are largely unknown in particular species. Here we investigated antiparasitic tactics in ground nesting Common Pochard Aythya ferina females towards intraspecific brood parasitism. Using a conspecific female dummy we experimentally simulated a situation where a female returning to her own nest is confronted with a conspecific parasite. The behaviour of the tested females towards the experimental dummy was compared with their responses towards the stuffed female Ring-necked Pheasant Phasianus colchicus used as a control. The reactions towards both dummies were similar: Pochard females typically swam silently around their nests and observed the dummy. The lack of differences between the measured parameters recorded in the experiments with conspecific and pheasant dummies may indicate that female Pochards do not recognize the conspecific intruder as a specific threat. In addition, the responses of the incubating female towards the conspecific female on her nest were studied using continuous video recordings. The defence was not sufficient, since the intruders were never expelled from the nest. The only rejection technique recorded was that of the parasitic egg being removed from the nest with the aid of the bill. The data indicate that active sophisticated anti-parasitic tactics have not evolved in Pochards, although there is some level of defence towards intruding conspecific parasites.

The use of sympatric Reed Warblers Acrocephalus scirpaceus and Marsh Warblers Acrocephalus palustris as breeding hosts: parasitism rates and breeding success of Common Cuckoos Cuculus canorus

100%

Sklepowicz B., Halupka L.

Acta Ornithologica

2009

tom 44

nr 2

We investigated the level of parasitism, rejection rates and breeding success of the Common Cuckoo Cuculus canorus parasitising two sympatric species of Acrocephalus warblers breeding in western Poland. In both hosts the frequency of Cuckoo parasitism was fairly constant throughout the breeding season. The parasitism rate (defined as the proportion of nests parasitised by the Cuckoo) was significantly higher in Reed Warblers Acrocephalus scirpaceus (12%) than in Marsh Warblers Acrocephalus palustris (4.6%). The rejection rate in Reed Warblers (7.4%) was the lowest ever reported for this species, while Marsh Warblers rejected 57.1% of Cuckoo eggs. As a result, the hatching success of the Cuckoo in Reed Warbler nests was higher than in Marsh Warbler nests (74.1% and 28.6%, respectively). The fledging success of Cuckoo chicks in the nests of the two host species was similar. Nest survival was significantly lower in parasitised nests than in non-parasitised ones. The breeding success of the Cuckoo (proportion of fledged young to the total number of eggs laid) was higher in the nests of Reed Warblers (29.6%) than in those of Marsh Warblers (7.1%), but the difference was not statistically significant. In 2001-2003 both host species were parasitised at a similar rate, but in 2004-2008 the level of parasitism dropped dramatically in Marsh Warblers. We discuss possible explanations for this phenomenon.

Ograniczanie wyników

2 Acta Ornithologica

1 Albrecht T.

1 Halupka L.

1 Honza M.

1 Neuzilova S.

1 Pialkova R.

1 Sklepowicz B.

2 2009

Wyniki wyszukiwania

Nest defence against conspecific intruders in the Common Pochard Aythya ferina: natural observations and an experimental test

The use of sympatric Reed Warblers Acrocephalus scirpaceus and Marsh Warblers Acrocephalus palustris as breeding hosts: parasitism rates and breeding success of Common Cuckoos Cuculus canorus