Friday, March 13, 2015

The Challenge of the Channel Island Fox

                                           
                                                   
                                                  TheChallenge of the Channel Island Fox
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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