Allen Cay, Bahamas - Island Conservation

Allen Cay, Bahamas - Island Conservation

Allen Cay, Bahamas
O U R MI SS IO N
To provide safe breeding habitat for native, threatened species on Allen Cay.
O U R V I S IO N
Native seabird and iguana populations are thriving in their natural habitat.
T H E P R O B LE M
Invasive house mice present on the cay negatively impacted native species,
including the globally declining Audubon’s Shearwater and Endangered,
endemic Allen Cay Rock Iguana.
T H E S OLU T IO N
WHY IS ALLEN CAY
IMPORTANT?
• HOME OF TH E I UC N
EN DANGERED, E N D EM I C
AL LEN CAY ROCK I G UA N A
• ON CE RECOVER ED, T HE
IS L A N D W ILL BE A BL E TO
S U P P ORT 1200 BR EED I N G
PA IRS OF AUDUBON ’ S
SHEA RWAT ER S
In 2012, The Bahamas National Trust and Island Conservation worked together
to remove invasive house mice from Allen Cay; the absence of invasive mice
will provide an opportunity for the island ecosystem to naturally recover.
T H E B I G PICT U RE
Invasive species are the leading threat to the Caribbean’s rich biodiversity. By
building local partnership and training practitioners in the region in invasive
species removal techniques, we are increasing capacity for island restoration to
permanently protect the Caribbean’s native species.
Allen Cay is located in the Northern
Exuma Islands, approximately 37 miles
southeast of Nassau, Bahamas. The cay
is long and thin in shape, with very few
trees. Following removal of invasive house
mice, natural cavities were filled with sand
to provide ideal breeding sites for female
Allen Cay Rock Iguanas.
A L L EN C AY RE STO R AT I O N P R OJ E C T
Allen Cay, Bahamas is home to an important population of the globally declining Audubon’s
Shearwaters and provides critical habitat for the endemic, Endangered Allen Cay Rock Iguana.
Invasive house mice on the cay were indirectly destroying native shearwater and iguana populations
by providing an abundant food source for Barn Owls. This in turn increased owl densities and enabled
year-round populations (the owls would normally migrate to another island). During the breeding
season, Barn Owls predated heavily on Audubon’s Shearwaters and juvenile Allen Cay Rock Iguanas.
It is estimated that the mortality rate for shearwaters was twice as high on Allen Cay as on nearby
islands without invasive rodents.
In May 2012, Island Conservation and the Bahamas National Trust worked together to remove invasive
house mice from Allen Cay to protect native species. Island Conservation trained Bahamas National
Trust staff in invasive species removal techniques to help build capacity for future restoration projects
in the Bahamas. The partnership will return to the cay in summer 2013 to confirm removal of invasive
house mice and monitor ecosystem changes. In the absence of invasive house mice, we anticipate a
significant increase in nesting shearwaters and rock iguanas.
TAKING ACTI ON TO CHANGE THE FUTURE
The rare
Allen Cay Rock Iguana is found naturally on only three islands worldwide (all
in the Bahamas) and has only two known breeding populations. Following the
activities to remove invasive house mice, scientists filled natural cavities on
the cay with sand to provide ideal nesting habitat for the iguana. If successful,
a dramatic increase is expected—Allen Cay is large enough to double the
current total iguana population in less than a generation (21 years).
1. ALLEN CAY RO C K IG UA N A ( CYC LU RA CYC H LU RA I N O R N ATA )
2. AUDUBON’S SHEA RWAT ER ( P U F F INU S LH E R M I N I E R I L H E R M I N I E R I )
Evidence for the decline of Audubon’s Shearwaters on Allen Cay is strong:
the vocal activity at night has fallen dramatically. Nesting areas on the cay
that were occupied in 2000 were empty by 2005 and have not recovered.
Audubon’s Shearwater has been extirpated from most of its former breeding
range in the Caribbean region. The expansion of safe breeding habitat for the
shearwater is essential to protecting this declining seabird from extinction.
The Bahama
Yellowthroat is endemic to the northern Bahama Islands and native to Allen
Cay. It inhabits thick, low scrub and undergrowth and nests close to the
ground in dense vegetation or a tree stump. Although similar to the migratory
Common Yellowthroat, it is slightly larger with a heavier bill and remains
resident year-round in the islands.
3. BAHAMA Y ELLOW T HR OAT ( GEOT H LY P IS ROST RATA )
There are thousands of islands in the Bahamas
Archipelago, including many protected sites in national parks, where invasive
species threaten native plants and animals. By working with local partners and
training them in invasive species removal techniques, we are helping build
capacity in the region for future island restoration projects that can benefit
seabirds, iguanas, and other wildlife in the Bahamas.
4. REGIONAL DEV ELOP M EN T