Chapters 1 - U.S. Fish and Wildlife Service

Chapter 4
experienced late rain showers, which resulted in the growth of weedy vegetation on the site. This
led to nest abandonment and predation of the remaining eggs (Collins 2007). In 2006, an unusually
high number of nests and eggs were lost for reasons that could not be positively documented;
however, great blue heron tracks were noted in the colony (Collins 2007). In 2007, predation by
both a great blue heron and a coyote, which greatly reduced the number of fledglings produced
that year, were observed and documented (Collins 2007). It has not been since 2000 that the
fledgling to breeding pair ratio has been above 0.70, which is considered by some to be the ratio
needed for a stable population (Fancher 1992).
The recovery strategies included in the California Least Tern Recovery Plan that are specific to
Anaheim Bay (Seal Beach NWR) include:
Preserve and manage existing nesting colonies, such as the one at NASA Island;
Develop and implement management plans to construct and manage new nesting sites
in protected areas including Anaheim Bay;
Protect and manage adequate feeding habitat for nesting colonies;
Monitor the least tern population to determine status, distribution, and progress of
management during the breeding season;
Conduct research to obtain necessary information for tern management (e.g., effects of
environmental pollutants, factors affecting choice of roosting, loafing, and feeding
areas used during breeding and post-breeding seasons, causes of colony disruption and
site abandonment, methods for enhancing nesting sites in existing colonies); and
Develop and implement a conservation education program.
The NASA Island nesting site is intensely managed immediately prior to and during the breeding
season. These activities are often implemented and/or funded through a partnership with the
Navy. Pre-nesting season activities include chemical and/or mechanical treatment or removal of
invasive weeds and grasses from the sandy nesting substrate; enhancing nesting substrate with
additional sand and/or shell fragments, as necessary; and making any necessary repairs to the
electrified chain-link fence that surrounds the site.
During the nesting season, the Refuge Manager and the Friends of Seal Beach NWR recruit and
train contractors and volunteers for the “Eyes on the Colony” program. Participants in this
program watch the nesting site and when necessary take actions to scare off potential predators,
such as crows and ravens. They also report any evidence of mammalian predators or evidence of
potential predation to the Refuge Manager. The nest site itself is also monitored weekly to
estimate and record breeding pairs; count nests, eggs, and chicks; and estimate the number of
chicks that are successfully fledged from the site. At the end of the nesting season, the monitoring
results are forwarded to the California Department of Fish and Game for inclusion in annual
California least tern breeding survey reports. Monitors also attempt to identify the causes of
adult, chick, and egg mortality, which can be due to predation (often recorded as potential,
suspected, or documented) or non-predation (e.g., abandonment, flooding, human damage). With
this information, it may be possible to modify predator management or site protection to avoid
such losses in the future. A predator management program has been approved for the Refuge and
is implemented year-round to control coyotes, feral cats and dogs, and other potential predators.
Predator management is conducted in accordance with the program developed in 1990 and
described in the Final Environmental Impact Statement for the Endangered Species Management
and Protection Plan prepared by the Service and NWSSB (USFWS and U.S. Navy 1990).
Another activity important to the recovery of this species is public education. The significance of
the least tern nesting site on the Refuge and the need to protect nesting colonies in other locations
4-62 Seal Beach National Wildlife Refuge