predators

Predation graphics for DTPC

 Predation TItle graphics for DTPC                           

 ravens & coyotes & dogs

Desert tortoises have several natural predators, such as coyotes, badgers, kit foxes, golden eagles, greater roadrunners and ravens. However, the impact of certain predators is increasing due to urban development and other human activities in the desert.

Coyotes are one of the top predators in the Mojave desert.

human subsidized

These predators thrive in and around desert towns by taking advantage of the resources humans unintentionally provide, and they prey heavily on desert tortoises.  The common raven, coyote, and domestic dog are serious threats to tortoises and other wildlife.

Tortoise pecked by a raven. Juvenile tortoise shells are too soft to withstand a raven’s strong beak.

RAVENS

Water: In a thirsty landscape humans irrigate crops, establish sewage treatment ponds and spray water over lawns and golf courses. Ravens are quick to learn how to get a free drink year-round, increasing their opportunities to breed and raise more ravens

Housing: Ravens readily build nests on power towers, microwave and radio towers and in abandoned cars and buildings. These sites give them protection from predators and a great view of the landscape. High perch sites make hunting as easy as scanning from the high cross-bar of a power line tower.

Food: French fries in dumpsters behind fast-food restaurants, rabbits and snakes killed on roadways, the remains of meals left in landfills and at campsites: with all of these we set a table for ravens and their nestlings. Ravens rarely miss a handout.

Other Comforts:  Ravens pass the hottest hours of the day in the shade of trees or buildings available in desert towns and cities.  Shade is another resource we provide free of charge.

All of this assistance makes life easy for ravens. Their numbers in California’s deserts have increased by over 1000% during the last few decades, roughly in step with the increase of human activity and numbers there. The more resources we make available the more ravens we create. And there are no predators to control their populations.

Historically, ravens were relatively rare in the desert due to the scarcity of essential resources and a lack of predators. The arrival of large numbers of people, homes, roads, and power lines have created a paradise for these intelligent birds. Ravens are masters at finding the food and water sources provided by humans and using these resources to build their populations.

COYOTES AND DOMESTIC DOGS

Coyotes, along with free-ranging dogs, are known to prey upon adult tortoises. Desert tortoise predation by coyotes has been found to be most severe in areas associated with human populations and subsidies, and when populations of other prey species are reduced due to drought or other causes. Unsupervised domestic and feral dogs attack tortoises in adjacent desert, and dog packs threaten both wildlife and human safety.

This tortoise survived a dog attack

 

The more predators we support, the fewer tortoises we will have. Ravens and coyotes are dedicated predators of both young and adult tortoises. In areas adjacent to cities and suburbs, along major highways, and anywhere ravens flourish, tortoises are being killed.

What you can do

  • Take all you bring in with you out again. Do not leave behind food or trash when you visit the desert. Coyotes and ravens will gladly take what you leave behind.
  • Use water sparingly and responsibly to minimize availability to ravens.
  • Keep a lid on your trash! Overflowing dumpsters or trash bins are perfect feeding sites for ravens and other predators. Even excess pet food left outside can help support the growing predator populations.
  • Dogs on leash. Do not let your dog roam off-leash in the desert and report sightings of feral dogs to local animal control.
  • Support efforts to control the exploding raven population. Political support of these projects is essential to the recovery of desert tortoise populations. A variety of techniques, both lethal and non-lethal, are available.

Dead tortoise. Cause of death: uncertain.