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The ecology of the black-headed honeyeater Melithreptus affinis in Tasmania, Australia

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Herman, K (2005) The ecology of the black-headed honeyeater Melithreptus affinis in Tasmania, Australia. PhD thesis, University of Tasmania.

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Abstract

The island state of Tasmania supports an environment unlike anywhere else in
the country. Historically the land has been exposed to glacial conditions, been
both isolated and attached to the rest of the continent. This has resulted in a
unique array of flora and fauna. Of the birds species found in the state, 12 are
endemic, and it is one of these species that is the focus of this study.
Melithreptus affinis is one of two members of this genus found in Tasmania,
both of which are endemic. It was first described in 1835, and although
known to science, little if any research has been undertaken on any aspect of
this species ecology. This study rectifies this.
In a context of the Tasmanian environment, the foraging and time budget of
M affinis was constructed. Literature has already shown that there are
significant morphological differences between M affinis and the mainland M
lunatus, species believed to be allopatric counterparts. In fact, within the
genus, both the Tasmanian species show much greater morphological
divergence than the mainland species. Results showed that M affinis used a wider variety of habitats, or increased
niche during this study, with foraging effort being distributed between
gleaning and probing methods. These variations were influenced by seasonal
factors and climatic conditions, showing the adaptability of the study species,
and how closely it has evolved with the Tasmanian environment. Versatility
was demonstrated when environmental conditions were less than optimal.
Continuing this broadening of niche is the species use of a wider array of
microhabitats than records show for Melithreptids on the mainland.
Microhabitat use was distributed between upper, mid and lower canopies,
whilst this genus is generally considered and upper canopy specialists. Again
these changes may be a response to the climatic conditions at the time of the
study.
To date the literature on the breeding biology of insular species is limited to a
small body pertaining to Northern Hemisphere species. Characteristics such
as lower clutch sizes, later laying dates, prolonged nestling development and
increased adult survival have been attributed to island populations. This study on M affinis was undertaken to determine if such trends were consistent in a
Tasmanian context. Analysis of both field data and museum specimens
showed that there were no discemable differences in most aspects of
reproduction. The characteristics shown by M affinis are consistent with
other members of the genus, as well as other members of the Meliphagidae
family, except the duration of the incubation period in the species. This
period is longer than would be predicted based on other members of the
family. It is hypothesised that this increase may be the result of a longer
history of this species in Tasmania and thus an adaptation to the colder
conditions experienced during the glacial periods. It is not possible to
compare this characteristic with the other endemic species, as this information
is not available.
The lack of variation in the reproductive traits of this endemic species allows
for this species to considered equivalent to continental species, and raises the
question as to the validity of insular or island effects on other aspects of the
species ecology. This species has evolved in isolation, in an environment that
has undergone substantial geological alteration, and has evolved in response
to these environmental conditions.

Item Type: Thesis (PhD)
Keywords: Honeyeaters
Copyright Holders: The Author
Copyright Information:

Copyright 2005 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.)--University of Tasmania, 2005. Includes bibliographical references

Date Deposited: 19 Dec 2014 02:48
Last Modified: 29 Mar 2017 05:28
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