Frugivory and North American Migrants in a Neotropical Second-Growth Woodland
Martin, Thomas Edward
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/77633
Description
Title
Frugivory and North American Migrants in a Neotropical Second-Growth Woodland
Author(s)
Martin, Thomas Edward
Issue Date
1982
Department of Study
Biology
Discipline
Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Ecology
Agriculture, General
Language
eng
Abstract
Bird species visitation to a single fruit source fluctuates over time due to changes in fruit density, presence of behaviorally dominant birds, and availability of alternative fruit sources. As a result, different bird species are major consumers of a fruit source at various periods of the fruiting season. Large dominant birds exploit a small-fruited species mostly at its peak availability. Large dominant birds displaced small birds, so small birds used the fruit less when dominants were abundant. Frugivorous migrants increase in abundance in late spring, due to migration, and they outnumber non-migrants in their representation at fruit sources.
Use of a fruit source by migrant and non-migrant frugivores is influenced by the net energy gain per unit time (profitability). I develop mathematical and conceptual models that describe fruit profitability to birds based on rewards provided by the pericarp (mass and nutrition yields) relative to costs (metabolic requirements, handling time, search time, behavioral interference) associated with finding and eating a fruit. The composition of birds at a fruit source is influenced by factors that determine profitability to individual bird species. Composition can vary over time as profitability changes and birds switch to alternative fruit sources.
The strategy employed by a plant to attract bird dispersers must act within this framework of factors that determine profitability and, hence, attraction of birds. In addition, plants are constrained by resource limitation and life-history considerations. Four factors that are important in determining profitability of a fruit to birds (seed size, absolute yield, nutritional yield, and daily fruit crop size) are directly controlled by the plant. These four factors are regulated by the plants relative to environmental influences, resource limitation, life-history considerations, and attraction of birds.
Frugivores vary in abundance within the second-growth community throughout the dry season. Recapture rates indicate that much of the fluctuation in abundance of frugivores is due to the movements of transients. Non-migrant frugivore abundance is negatively associated with migrant frugivore abundance; when migrants flood the community during spring migration, non-migrant frugivores decrease in abundance. Fruit abundance is high and many of the fruits of second-growth habitats are small, possibly causing selection of second-growth habitats by migrants.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
