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Title:Manipulating social information to promote frugivory by birds on a Hawaiian island
Author(s):MacDonald, Sean Erroll
Advisor(s):Sperry, Jinelle H
Department / Program:Natural Res & Env Sci
Discipline:Natural Res & Env Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(s):conspecific attraction
fruit-eating bird
Hawaiian flora
playback experiment
seed dispersal
social information
Zosterops japonicas
Abstract:Animals across a range of taxa use social information when foraging. Fruit-eating vertebrates are no exception and use social information to find fruit, which may ultimately affect plant populations via seed dispersal. In many systems, mutualistic relationships between fruiting plants and frugivores are critical to maintain ecosystem functioning, especially in the tropics. On the island of Oʻahu, Hawaiʻi, all native, fruit-eating birds are extinct and several plant species are experiencing reduced recruitment likely due to a lack of seed dispersal. Over the years, numerous bird species have been introduced to the island many of which are frugivorous. Yet, introduced birds may not recognize native fruits as a resource and social information may be needed for introduced frugivores to target and feed on native fruits. We investigated if social information, in the form of broadcasted bird vocalizations, of introduced birds could increase visitations and more importantly frugivory on focal fruiting plants. We also tested if the visitation rates to focal plants were influenced by conspecific and/or heterospecific vocalizations. We conducted 80 playback experiments at native and introduced fruiting plants, and compared responses to silent control periods. Four times as many frugivores were detected and 10 times more frugivory events were recorded at plants during periods of broadcast vocalizations compared to control periods. The Japanese white-eye (Zosterops japonicus) exhibited the strongest response to both conspecific and heterospecific playbacks. Japanese white-eyes also consumed the most fruit from the widest array of plant species during trials. Introduced birds that use social information and readily identify novel resources may more effectively colonize new areas. We suggest that the white-eye’s use of social information may help to support their robust population on Oʻahu. Ecosystems throughout the world are affected by the loss of mutualistic relationships, many of which provide valuable ecological services. As humans continue to modify environments, novel conservation approaches may be required to maintain important ecological functions.
Issue Date:2019-07-18
Type:Text
URI:http://hdl.handle.net/2142/105700
Rights Information:Copyright 2019 Sean Erroll MacDonald
Date Available in IDEALS:2019-11-26
Date Deposited:2019-08


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