They were wide-eyed and anxious one moment, then bursts of cinnamon blurs, bounding freely over and through dormant grasses for the first time in their endangered lives the next. Eighteen island foxes were released on the National Park Service property of Santa Cruz Island for the fist time since captive breeding began on the largest of the Channel Islands in 1999.
The foxes were brought over on an Island Packers boat from the captive breeding facility in the Central San Joaquin Valley on Nature Conservancy property to replenish what has been a sparsely populated region for the largest land predator on the Channel Islands. Biologists chose strategic sites on the southeast end of Santa Cruz, where there were less foxes from Potato Harbor to Smugglers Cove. The foxes were transported in small cages to each site where males and females were paired up when released. Before the release, biologists had trapped 20 individual foxes to gauge territories and numbers in the region. There’s still the worry that captive-bred foxes will run into established territories and aggressive encounters will ensue, especially amongst males pursuing females in January. In all, 58 foxes have been released this fall on Santa Cruz.
\”That’s key; we want to avoid that as much as possible,\” explained Tim Coonan, terrestrial biologist for the NPS. \”Sometimes they run into each other. It does occur when choosing mates with hardcore breeding activity in January. Hormones rise and they get very aggressive.\”
Captive breeding has gone so well on the island that it’s possible the last release of the remaining captive population could be in the fall of 2007. The wild population is also on the rise, culminating with the eradication of the feral pig population and no golden eagle predation since last spring.
\”We’re about done with captive breeding on Santa Cruz,\” said Coonan, who has been involved with the recovery of island foxes on the entire archipelago. \”The wild population has grown dramatically in the last couple years, and the fall of ’07 could be the last big release of captive-bred foxes. Things are looking so good on Santa Cruz and San Miguel.\”
Santa Cruz has the largest wild population, with around 300 individuals covering the mountainous islet. Twenty-five foxes remain in captive breeding, but those won’t be released until they have their pups in the spring and the new pups have grown ready to venture on their own in the fall.
\”Fall is the best time to release the foxes,\” continued Coonan. \”The pups have grown. It’s ideal for that.\”
San Miguel Island has also seen a spike in its wild and captive populations. Coonan said the survival rate on the windswept islet is very high for the wild population, at 90 percent. Twenty-five pups were born in the wild last spring, and there are now 77 individuals establishing territories across the island.
The same can’t be said for Santa Rosa Island. Although Coonan said there are no remaining golden eagles on the second largest of the Channel Islands, the wild island fox population is still very low, at around 50 individuals with 28 animals in captive breeding.
\”The small population of foxes on Santa Rosa can be attributed to the most recent bout of golden eagle predation during the winter and spring of ’06,\” he said. \”We’re heading into golden eagle season right now.\”
Biologists will be keeping a close eye for the raptors that show up in the winter to build up their resources to breed, which happens in February.
\”We’re really cognizant of this fact,\” he said.