Please Note:

The Open Access Repository has moved to a new authentication system as of the 1st of November.

Account holders will now be able to login using their University of Tasmania credentials.
If you have trouble logging in please email us on E.Prints@utas.edu.au so we can assist you.

Public users can still access the records in this repository as normal

Open Access Repository

The Shy albatross (Thalassarche cauta): Population trends, environmental and anthropogenic drivers, and the future for management and conservation

Downloads

Downloads per month over past year

Alderman, RL (2012) The Shy albatross (Thalassarche cauta): Population trends, environmental and anthropogenic drivers, and the future for management and conservation. PhD thesis, University of Tasmania.

[img]
Preview
PDF (Front matter)
front-Alderman-...pdf | Download (596kB)
Available under University of Tasmania Standard License.

[img]
Preview
PDF (Whole thesis excluding Ch. 2,3 & App. ix)
whole-alderman-...pdf | Download (1MB)
Available under University of Tasmania Standard License.

[img] PDF (Whole thesis including published material)
whole-alderman-...pdf | Request a copy
Full text restricted until 2111.
Available under University of Tasmania Standard License.

Abstract

Despite recent global conservation efforts, albatrosses remain amongst the most threatened groups
of birds. Worldwide, they are affected on land and at sea by a range of processes, particularly
fisheries bycatch. In spite of their high conservation profile, albatrosses present challenges for
monitoring and recovery actions because they are long-lived, spend most of their life at sea and
return to breed at colonies that are often located on remote, relatively inaccessible islands.
This thesis offers a comprehensive assessment of the population status and trends of Australia’s
endemic shy albatross, Thalassarche cauta, which breeds exclusively on three Tasmanian offshore
islands. The main anthropogenic, physical and environmental processes that influence each of the
three breeding populations are examined and the processes that shape key demographic
parameters and trends are assessed in four analytical chapters which follow the introductory
chapter.
Chapter two compiles and analyses available population and demographic data to provide the first
comprehensive assessment of the status and trends of the three individual shy albatross colonies
and of the species as a whole. This chapter shows that the Albatross Island population has recently
stabilised following a period of sustained increase post-harvest and that this change in trajectory
appears driven by a decrease in juvenile survival. The small Pedra Branca population is declining,
likely due to reduced breeding success associated with the increasing population of Australasian
gannets on the island. While trends for Mewstone, the largest breeding population, are unknown, it
is shown that birds from this colony have greater exposure to commercial fisheries, are therefore at
higher risk of fishing-related mortality and, consequently, survival rates for this population are likely
lower than their Albatross Island counterparts. Collectively, these results suggest the current status
of the shy albatross is likely to be stable at best and quite possibly decreasing.The third chapter uses satellite tracking data to investigate the at-sea distribution of post-fledging
shy albatrosses. Data show colony-specific dispersal behaviour and subsequent post-fledging range.
Accordingly, the three populations differ in the extent to which juveniles overlap with commercial
fisheries and their consequent risk of by-catch. The satellite data and supporting evidence from band
recoveries also show that juvenile mortality is highest in the period immediately after fledging, with
population differences in the frequency of mortality also apparent. Post-fledging mortality is likely
related to foraging failure of naive birds and the observed population differences may be related to
proximity of colonies to food resources. Considering the combined impact of environmental and
fisheries influences, it is probable that the juvenile survival rates for the two southern populations,
and for Mewstone in particular, are lower than the northern, well-studied, Albatross Island
population.
In line with the increasing focus of managers and researchers on understanding climate impacts on
threatened species, chapter four assesses the efficacy of existing long term monitoring on Albatross
Island in detecting the influence of climate change on the breeding performance of this population.
This study shows that the current sampling design is biased towards older, more experienced
breeding individuals, which are better able to buffer the effects of climate variability and thereby
obscure climate signals. Modifications to the monitoring protocols are suggested, including the
deliberate sampling of younger birds to provide a more sensitive and effective ecological indicator of
the effects of climate variability and climate change on this population.
The fifth chapter takes the existing breeding-success time-series and investigates the relationship of
this important life-history parameter with a range of local and regional environmental variables. The
strongest relationships were found with environmental conditions during chick-rearing, including
rainfall and maximum temperature during this period at the breeding site, and with sea-surface
height anomalies associated with increased upwelling in the primary foraging areas during both incubation and the chick-rearing phases. The population implications of these climate-biology
relationships given future predictions for climate change are considered.
These findings are synthesised to produce the first comprehensive report of the overall conservation
status of the shy albatross and a key conclusion of this research is that the species is not as secure as
previously believed. In addition to contributing to our understanding of the status of the species, this
thesis highlights a range of threatening processes and their underlying mechanisms and provides
clear guidance for future management and monitoring of this species, findings that can be extended
to other threatened seabird species.

Item Type: Thesis (PhD)
Keywords: shy albatross, demography, population trends
Additional Information:

Copyright 2012 the Author

Date Deposited: 17 Aug 2012 04:33
Last Modified: 15 Sep 2017 01:06
Item Statistics: View statistics for this item

Actions (login required)

Item Control Page Item Control Page
TOP