Channel Islands,
California
Alanna Reilly
Luminous eyes, red belly and a grey speckled coat characterize
this fierce (ish) predator. A more minute version of its mainland cousin,there
are 6 subspecies of Channel Island fox, 4 of which underwent massive population
decline in the late 1990s to early 2000s. They have naturally small populations
and, as top of the food chain had, little reason to ever feel fear in the past. These foxes were vulnerable to new any threat, and with a high rate of
invasive species dispersal (including humans) globally, it was only a matter of
time before that vulnerability was exposed.
The Biggest Threat: Non Native Species.
When the non-native Golden Eagle started
to hunt the foxes, they had no defense against aerial predators. The Golden
Eagles outcompeted the native Bald Eagle(which posed little threat to the
foxes) and the lack of Bald Eagles further bolstered the new predators numbers.
The Golden Eagle wasn’t the only non-native enemy though. On San Catalina Island foxes were killed off
by Canine Distemper Virus, brought over by a stowaway Raccoon. The naturally
small populations, ranging from 500-1500 foxes per island, were decimated by
the disease due to lack of genetic diversity. Feral pigs and grazers had also
drastically altered the plant life on the island, removing natural grasses
that could have provided concealment
from the Golden Eagles.
The population drops on the islands were drastic:
San Miguel: 450
adults-15 in 1999.
Santa Cruz Island:2000 adults in 1994 - 60 in 2000.
Santa Rosa Island:1500 adults in 1994- 15 in 2000.
The need for action was urgent, and the fox population were
desperate.
THE RECOVERY PLAN:
In 2004, 4 of
subspecies were listed as endangered by the U.S Fish and Wildlife Service under
the federal Endangered Species Act.
First step:
The Island Fox
Conservation Working Group consulted a variety of experts and after two years of monitoring and
establishing threats, a draft was
developed in 2006. It included translocation of the Golden Eagles, capturing
and breeding the remaining foxes, while also vaccinating them to prepare them
for eventual re-introduction to the wild. Island Foxes had never been bred in
captivity before so the Association of Zoos and Aquariums collaborated with
local zoos to come up with efficient breeding conditions. However, to protect
the organism you must protect the habitat. The removal of non native ungulates,
with the reintroduction of Bald Eagles onto the islands helped to bring the
ecosystem back into balance. From 2002-2006 young Bald Eagles were
re-introduced to the island to provide natural competition for the Golden
Eagles, and in 2006 breeding was documented.
Challenges faced:
Although
Fox populations grew quickly at first, a few factors slightly hindered
population growth later in the program:
1.
Male aggression
lead to fighting and injury amongst the captive foxes
2.
Female
abandonment of pups
3.
An outbreak of mastitis amongst the Santa Rosa
and San Miguel Facilities
Due to careful monitoring and some adjustment to the plan,
factors that led to more successful reproduction were identified and addressed.
The Foxes Today:
By 2004 Santa
Catalina facilities had released a total of 57 foxes back into the wild, and
the northern islands following suit with
a total of 254 foxes released by 2008. By 2012, foxes had reach pre-decline
population on San Miguel and Santa Cruz Islands. All released foxes were
radio-collared, and there has been an 80-90% survival rate. These guys are back on their feet, and with the support and careful supervision of the Channel Island Fox Conservation Group, they'll stay that way.
Sources:
picture 1: http://www.edhat.com/daypics2011/sbzoo13.JP
2: http://www.photobotos.com/golden-eagle-attacking-fox/
3: http://www1.islandfox.org/2014/07/channel-island-fox-status-update-june.html
4: https://xenophobia22.wordpress.com/tag/california/
5: http://www.sbcondors.com/california-trails/fox/
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