Condors: A Sight for Soaring Eyes
So many things must come into play in order to reach our ultimate goal of self-sustaining California condor populations in the coming years. Especially in Baja, Mexico where we have to deal in two cultures, economies and lands capes. One major plus is that our Mexican team of biologists sports endless energy and know how, having been with the program since it began in 2002. They braved mountains of permits and paperwork when the first five pioneer condors joined the program.
In the US, program managers collect condor food from stillborn cows from dairies. In Baja, we ask the local ranchers first if they have any carcasses available and canvass the landscape for dead or dying livestock much like the condors do on their own once released. These food animals go to supporting the condors in the aviaries prior to release, as well as after.
We use the carrion to teach the birds the rudiments of foraging by strategic placement of carcasses throughout the landscape in a pattern that challenges but not overwhelms the fledgling population. The rule of thumb is to manage the food placement with special emphasis on the least able to forage birds in the flock. The other, more experienced birds figure it out first and the less experienced birds follow their example.
When we began the Baja reintroduction program in 2002, there was a hope that there would be enough carrion in the Sierra San Pedro area to support a population of approximately 50 condors. The only real way to know was to let the birds “tell us” after they developed sufficient foraging abilities and study their patterns and level of foraging success. Also an important part of the equation is our own education about the release landscape and where sufficient carrion might be available.
Over the past decade, the birds have expanded their foraging range to about 350 square miles finding dead deer, bighorn sheep, and livestock but it does not appear to be enough.
At the Big Sur release site, managed by the Vantana Wilderness Society, condors feed mostly on beached marine mammals. This was a historical food supply for condors but over harvesting by humans in last century nearly ended these species as condor diet items.
That has changed.
While marine mammals are now an abundant and rich food source, levels of residual DDT have caused some egg breakage. Fortunately the pesticide levels are diminishing in the area making this food supply a promising bet for the condor’s future in northern California.
Just 250 miles south of the condor release site in Baja are colonies of sea lions and grey whales. Sources indicate that the DDT levels should be much lower than those found in the California marine mammals, but we need samples tested to be sure. Southern Baja coastlines offer tremendous potential as condor foraging areas if we can get the birds to realize it.
Three methods, or a combination of them, would likely be successful:
First, transplanting several experienced condors part way to the southern destination and letting them fly back, homing pigeon style, to get them used to the area and the route. But since there are no other condors to the south, they will not stay.
Second, they could be taught the path to the south by using fixed-winged drones painted to look like condors and flown to consecutive feeding sites to teach condors the route. But again, without other condors in the area, they may not return.
Third, by releasing a small group of 5 or 6 birds in the high food concentration area, methods one and two could be employed as the released birds become established.
Reaching self-sustainability is an important goal in our wild California condor populations. With a little more work we will achieve it in Baja.
Mike Wallace, Ph.D., Program Manager