Peregrine Falcons Returning to the Channel Islands

On June 10, Brian Latta, a scientist with the Santa Cruz Predatory Bird Research Group (SCPBRG) , spoke at the Santa Barbara Harbor as part of the Channel Islands National Park’s “From Shore to Sea” lecture series. Latta’s lecture focused on the reestablishment of Peregrine Falcons in the Channel Islands off the Santa Barbara coast.

As a result of contamination from the pesticide DDT (Dichloro-Diphenyl-Trichloroethane), the falcon had been classified as endangered since the 1970s, resulting in a need for measures of human intervention such as captive breeding. Biologists discovered that DDT was harming birds and banned the pesticide in 1972. Birds like the peregrine falcon that sit high on the food chain would eat animals that had consumed DDT and absorb the substance to the point that their eggshells become thin and crack before hatchlings had time to mature. Unfortunately, the pesticide stays active for decades. Jim Roush, one of the founding members of SCPBRG, heard of the captive breeding of peregrine falcons in the early 1970s by Dr. Tom Cade at Cornell University, and, along with Ken Norris of UC Santa Cruz decided to do the same on the west coast. Brian Walton soon joined the cause, coordinating the breeding of the birds.

One thousand peregrine falcons were bred in captivity in the 1970s by SCPBRG in Santa Cruz, and were released between 1977 and 2007. SCPBRG employees would climb to peregrine nests, leaving fake eggs in the place of the thin shelled eggs they took to the laboratories to hatch. The newly hatched birds were then taken back to the adults, allowing them to be cared for. If adults were not around, the chicks would then be taught to live and hunt in the environment on their own by being placed in a hack box, where for seven days, daily food would appear for the chicks, with the humans making sure they were not seen so as to prevent the birds from becoming dependent upon them. The U.S. Fish & Wildlife Service removed the bird from the Endangered Species List in 1999.

During his lecture, Latta described the ways in which SCPBRG has been helping peregrine falcons on the Channel Islands. He explained that the progress of captive-bred birds is monitored by employees who travel to the islands to record the birds’ progress. From a few miles away, researchers examine the birds through cameras, waiting until they leave their nests to check on the shells of eggs, making sure that they are stronger.

The first breeding pair of peregrine falcons was re-established in 1986 on the island of San Miguel of the Channel Islands. By 1994, there were nine pairs that were reestablished on the island, and today there are twelve. The Channel Islands today holds 37 breeding pairs.

While inland peregrine falcons in California originally were doing better than coastal peregrines, there has been a large improvement in productivity and eggshells have strengthened.

To read more about the Channel Islands National Park’s “From Shore to Sea” series, click here.