Download Breeding Patterns of Wedge-tailed Shearwaters at Freeman Seabird

Keeping Common Birds Common: Breeding Patterns of Wedge-tailed
Shearwaters at Freeman Seabird Preserve, O`ahu
Harrison Pravder
Hokule`a Program, Washington University in St. Louis
INTRODUCTION
Conservation Climate
A staggering 340 out of the United States’ 1500 endangered species
call
Hawai`i home. These species are protected under the Endangered
Species Act (ESA). Under the act, species at risk for extinction are
targeted for revival. The ESA consumes much of the US Government’s
allocated funds for conservation activity, thereby directing funds
away from common species, species that are crucial for sustained
ecosystem stability.
Wedge-tailed Shearwater
The Wedge-tailed Shearwater (Puffinus pacificus) (also known as a
wedgie) is a medium-sized petrel native to the Hawaiian archipelago.
With an estimated population of 5.2 million individuals worldwide,
wedgies range throughout the tropical Indian and Pacific Oceans.
Despite being greatly affected by introduced predators and human
habitat interference, wedgies are not considered at risk under the
ESA, and thus are not given much attention to by conservationists.
They are, however, protected under the Migratory Bird Treaty Act, an
act that discourages human disruption of migratory bird activities.
Nonetheless, human activity (via habitat destruction and other
means) has lead to an ongoing global wedgie
population decrease of unknown rate.
Freeman Seabird Preserve (FSP)
The last breeding ground for wedgies on the
south
shore of O`ahu, FSP is a preserve that was
established
by the Hawai`i Audubon Society in 2008 after a
generous donation. Efforts to improve breeding
conditions for wedgies have had great success.
My Work
My work focused on monitoring wedge-tailed shearwaters at FSP and
evaluating regional population threats through necropsies. My
monitoring efforts strove to document WTSH nesting and fledging
success on the preserve and to identify local threats to the colony. In
the necropsies, I examined all parts of the deceased seabirds and
Bird Monitoring
evaluated several organs for external abnormalities, such as plastics
I went to the Freeman Seabird Preserve on a
and toxins.
nearly daily basis to inspect the nests.
I looked for:
1. Eggs
2. Adults with eggs
3. Adults without eggs
A Bushnell® 8MP motion-activated
camera was set up at different locations
around the preserve each day. Photos
and/or videos were taken and analyzed.
Necropsies
I performed necropsies at the Oceanic
Institute (Waimanalo, HI) on a weekly
basis. Three WTSH were necropsied.
Samples were taken for pollutants, and
FREEMAN SEABIRD PRESERVE
★
RESULTS/OBSERVATIONS
NUMBER OF NEW EGGS LAID
CUMULATIVE NUMBER OF EGGS LAID
METHODOLOGY
A cat seen visiting the
Freeman Seabird
Preserve at night.
A Siamese house cat
seen at the Freeman
Seabird Preserve
during the day.
Night activity at the Freeman Seabird Preserve.
*Note: All pictures taken with Bushnell® 8MP Motion-Activated
DISCUSSION
Breeding Information
• A bimodal distribution was observed for egg laying with
two peaks arising on June 21st and 24th (Julian days 172 and
175).
• The June 24th peak coincided with a full moon.
• Mean=July 22, Median=July 21
WTSH Observations
• The colony continues to expand the number of breeding
pairs.
• Many birds nesting in “artificial homes”.
• Few birds nesting in native vegetation (5 Birds).
• Nesting in ʻohai, ʻilima papa, and naio.
Necropsy Findings
• Plastics seen in all birds mostly in the form of fishing line.
Predatory Activity
• Predatory activity observed from cats and humans.
• People seen walking barefoot through the
preserve towards the ocean.
CONCLUSIONS
• Work is needed to assess all species, not just those that are
threatened/endangered.
• This study contributes to increasing our knowledge base of
one common species; more work is needed to study other
species.
• We need to ensure that common species
remain common, for without common
species, the ecosystem would suffer drastically
due to loss of essential ecosystem services.
• It is more cost-efficient in the long term to protect species
that can be preserved, rather than bring back deprived
species.
• Several measures can be taken to protect all species:
1. Limit invasive predators
2. Protect native habitat
3. Limit human exposure
• Priorities must be set to maximize each
dollar spent.
• There are trade-offs in every conservation
action. With limited funds, we need to
maximize the overall benefit.
• Public outreach efforts are necessary to educate the
community of conservation issues and to inform the public
of their role in this ongoing issue.
I would like to express my sincere thanks to Dr. K. David
Hyrenbach for his thorough guidance and generosity
throughout my time in Hawai`i. I would also like to thank Anu
Hittle without whom the Hokule`a program would not exist
and for all of the great experiences I enjoyed because of her
leadership. Additionally, I would also like to thank Dr. Tiffany
Knight for her support throughout the process. Funding was
provided by the WU Environmental Studies Program, WU
ACKNOWLEDGMENTS