Peregrine Falcon Territories Increasing on the Channel Islands

A Peregrine Falcon flying above the Channel Islands. (Institute for Wildlife Studies)

Peregrine Falcons are an apex predator on the Channel Islands which means that they feed on the top of the food chain and their presence is an important part of a healthy ecosystem. Peregrine Falcons were eliminated from the Channel Islands by 1960 because of reproductive failures associated with DDT contamination in the marine environment. The Santa Cruz Predatory Bird Research Group released 37 Peregrine Falcons on the Channel Islands from 1983-1998 in an effort to restore them to the islands.

MSRP has funded several surveys to monitor the recovery of the Peregrine Falcon on the Channel Islands with a focused survey on Santa Catalina Island in 2004 and two comprehensive surveys on all eight islands in 2007 and 2013. The Santa Cruz Predatory Bird Research Group completed the survey in 2007 and documented 25 active territories across 6 of 8 islands. During the 2007 survey, 10 previously unknown or unconfirmed territories were documented.

In 2013, biologists from the Institute for Wildlife Studies (IWS) conducted weekly surveys to locate known and new nesting locations. Biologists broadcasted Peregrine Falcon vocalizations in potential territories to help with locating more nests. IWS located a total of 45 active territories with at least one territory on each island. This was almost double the number of active territories discovered during the 2007 survey. The breakdown of territory locations was as follows: 10 on San Miguel Island, 11 on Santa Rosa Island, 14 on Santa Cruz Island, 3 on Anacapa Island, 2 on San Nicolas Island, 3 on Santa Barbara Island, 1 on Catalina Island, and 1 on San Clemente Island. The five most northern Channel Islands are the primary stronghold for Peregrine Falcons most likely because of their proximity to the mainland and the large number of seabird colonies which is a main food source for peregrines. IWS biologists counted a total of 69 Peregrine Falcon chicks that hatched this year and banded 50 of the chicks to track them from year to year.

Peregrine chicks in their nest after banding. (Jim Spickler, Eco-Ascension Research and Consulting)

For the upcoming 2014 season, IWS biologists will continue to monitor both Peregrine Falcons and Bald Eagles on all eight islands. By conducting annual surveys for both species, we will better understand the population dynamics of both species and evaluate potential on-going impacts of DDT contamination. As part of the monitoring program, IWS will collect any failed eggs, eggshell fragments, nestling feathers, and prey remains for future analyses. For weekly updates on the Peregrine Falcon and Bald Eagle surveys on the Channel Islands in 2014, visit the Channel Islands Live! Discussion Forum.

-Annie Little, U.S. Fish and Wildlife Service