Thursday, May 06, 2010

It's Pupping Season for Island Foxes

Across the Channel Islands a new generation of island foxes are being born. Each litter of pups are an important step toward full recovery for the endangered populations on San Miguel, Santa Rosa, Santa Cruz, and Santa Catalina Islands.

Island foxes reproduce only once a year, in the spring. This year's weather has been good for native plants which suggests we could see a large number of healthy island fox pups.

With small parents, island fox pups, or kits, are very tiny at birth. They weigh approximately the same as two AAA batteries and would easily fit in the palm of your hand.

Young foxes are very vulnerable and are born in a den. The den provides protection from weather and other animals
for the first weeks of their lives. Here the mother feeds them milk until they start to eat solid foods. The father brings food back to the den both for his mate and the pups.

Unlike most other canines, island foxes don't appear to dig. They must find a den site either in a hole dug by another island species, (spotted skunk, ground squirrels, etc.) or a naturally made hollow under dense vegetation, tree roots or rocks.
Pups born in March or April are emerging from dens on the islands in May. Both parents care for the youngsters, helping to feed them and teaching them how to find food. This pup is with its father, an older male, in the fog on San Nicolas Island.

Island foxes grow up fast and by September they will be ready to leave their parents and strike out on their own. Annual counting of island foxes doesn't occur until the fall to insure that pups are weaned and somewhat independent. During trapping and counting, island foxes also undergo annual health checks. Radio monitoring collars are replaced or put on and island foxes are given vaccinations against distemper and rabies.

Last year biologists recorded impacts on island foxes from climate change. Continued drought reduced fruit on the islands' native plants. The combination of increased temperatures, low rainfall and reduced food resources caused the litter size born to each pair of island foxes to be small. A normal island fox litter is 2-3 pups. In good years, litters of up to 5 pups are possible. Unfortunately, the pups born in 2009 also had reduced birth weight, impacting their survival.

This year's normal rain levels may bring more positive pup numbers. Biologists are hoping for numerous healthy pups to continue the island fox's successful recovery.