title: Fluff-thieving birds sabotage seed dispersal.
abstract: Characterizing many species interactions as mutualisms can be misleading because some members of the interaction derive greater fitness benefits at the expense of other members. We provide detailed natural history data on a suspected bird-plant mutualism in South Africa where many species of birds use fluffyEriocephalusseed material to construct their nests, potentially dispersing seeds for the plant. We focus on a common bird,Prinia maculosa, which invests heavily in gatheringEriocephalusmaterial. Prinias spent 5 of their median 6-day nest construction period adding seed material to their nests and frequently travelled outside their territory boundary to gatherEriocephalusmaterial. Yet, prinias gathered primarilyEriocephalusfluff and actively avoided gathering seeds. The average prinia nest contained only 6.6 seeds, but contained fluff from 579 seeds. These data suggest that prinias provide limited dispersal benefits toEriocephalusplants. By contrast, the large amounts ofEriocephalusfluff in prinia nests, and the effort that prinias invest in gathering it, suggest that prinias benefit from constructing their nests withEriocephalusmaterial. We end by outlining hypotheses for possible fitness benefits thatEriocephalusmaterial could provide prinias and other birds.
authors.affiliation: Department of Biology , Queen's University , Kingston, Ontario , Canada K7 L 3N6.
authors.forename: Vanya G
authors.identifier: 0000-0002-2505-3761
authors.initials: VG
authors.lastname: Rohwer
authors.affiliation: Department of Botany and Zoology , Stellenbosch University , Private Bag X1, Matieland 7602 , South Africa.
authors.forename: Anton
authors.identifier: 0000-0002-4012-648X
authors.initials: A
authors.lastname: Pauw
authors.affiliation: Department of Biology , Queen's University , Kingston, Ontario , Canada K7 L 3N6.
authors.forename: Paul R
authors.identifier: 0000-0003-2611-1211
authors.initials: PR
authors.lastname: Martin
keywords: Eriocephalus; Karoo prinia; mutualism; parasite; seed dispersal