REPRODUCTIVE SUCCESS OF EURASIAN TREECREEPERS,CERTHIA FAMILIARIS,LOWER IN TERRITORIES WITH WOOD ANTS

Abstract

Few studies have considered the effects of interspecific competition between distantly related taxa on the reproductive success of individuals. We compared the food supply, laying date, clutch size, and breeding success of a small double-brooded passerine bird, the Eurasian Treecreeper (Certhia familiaris) between territories with or without colonies of red wood ants (Formica rufa group) during four years. Both the wood ants and Eurasian Treecreepers forage on tree trunks and utilize the same food resources. It has been shown that the wood ants are able to depress the available food supply for the treecreepers and interfere with their foraging behavior. We found that food abundance was lower in territories colonized by wood ants, and that this difference was more pronounced during the second clutches. In territories without ants, treecreepers started breeding earlier and increased the size of second clutches, whereas birds breeding in territories with ants decreased clutch size in second breeding attempts. In addition to hatching later, nestlings in territories with ants achieved lower body mass near fledging and suffered higher mortality than nestlings in territories without ants.Consequently, double-brooded treecreeper pairs produced an average of 2.3 more fledglings, also of higher quality, in territories without ants than in territories with ants. There were no differences between the territory types in any measure of habitat quality other than food abundance. Our results suggest that wood ants reduce territory quality of Eurasian Treecreepers by means of food depletion and have negative effects on the breeding success of individual birds. These results show that competition between organisms in different phyla may be effective in determining the reproductive success of individuals.

Impacts of major predators on tropical agroforest arthropods: comparisons within and across taxa

“…Ants were unavailable to birds on no-ant branches, and if ants, in coffee systems, constitute a large part of bird diets, bird predation on other arthropods may have significantly increased where ants were excluded masking isolated effects of ants on arthropods. Alternatively, aggressive ants may deter bird feeding (Aho et al 1999;Haemig 1992Haemig , 1996. In this case, if ants significantly limit bird feeding when both predators are present, bird predation also would have increased and may have compensated for effects of ant removal, masking large effects of one or both ant species.…”

Forest fragmentation is associated with primary brood sex ratio in the treecreeper (Certhia familiaris)

“…In our nest-box population, the first eggs are laid in early April, when snow cover and night frosts still prevail in central Finland. Approximately 30% of the first breeders raise a second brood in June and July, which is usually reared by only the female (Aho et al 1999). Almost all juveniles migrate from the study area as a result of natal dispersal, whereas breeding birds are suggested to be sedentary (P. Suorsa and H. Hakkarainen, unpublished data).…”

“…We measured food abundance using vacuum cleaners on spruce and pine trunks during the period immediately after the fledging of the young treecreepers (Aho et al 1999). The trunk surface between the heights of 0.5 and 1.5 m was vacuumed in dry weather between 09.00 and 18.00.…”

Distribution of Mound-Building Ant Species (Formicaspp., Hymenoptera) in Finland: Preliminary Results of a National Survey

“…Savolainen & Vepsäläinen 1988, Niemelä et al 1992, Way & Khoo 1992, Karhu & Neuvonen 1998, Laakso & Setälä 2000, Martikainen et al 2000, Sipura 2002, Punttila et al 2004) and vertebrates (e.g. Haemig 1992, Aho et al 1999, Jäntti et al 2007) in all forest layers from the forest soil and floor up to the tree trunks and canopies. Further, they are important resource for both invertebrates and vertebrates (e.g.…”