appendix b final 2008 biological surveys of los angeles and long ...

9.0 Birds
surveys at a subset of harbor locations in contrast to other historical studies that included at
least monthly surveys.
Differences in survey methods also may contribute to differences in the number of birds counted
between recent and historical studies (Figure 9.6-2). The current and 2000–2001 (MEC 2002)
surveys covered more open water than previous studies. Open water, along with riprap and
dock/pilings, supports the greatest numbers of birds in the Ports. On average, several thousand
birds were counted per survey during these recent studies. Several thousand birds were also
counted per survey during the 1973–1974 study of inner and outer harbor areas, even though
those surveys excluded open-water habitat. In contrast, substantially fewer birds were counted
when studies were limited to the outer harbor areas or were based on less frequent quarterly
surveys (HEP 1979, MBC 1984, MEC 1988). Due to the fidelity of a number of species to
particular habitats and location (e.g., Brown Pelicans and Black Oystercatchers on outer
breakwaters, and Western Gulls on inner harbor docks), an increase in survey area generally
corresponded to an increase in total abundance of birds, but not necessarily to an increase in
abundance of each individual species.
Despite the differences associated with methodology, there have been changes in the relative
abundance of some bird guilds over time (Figure 9.6-3). A major difference between earlier and
more recent studies has been the decrease in dominance by gulls and increase in other bird
guilds. Some increases in other bird guilds (e.g., Upland Birds, Waterfowl) are likely due to
expanded survey areas in the more recent surveys. Recent nesting of Brandt’s and Doublecrested
Cormorants also increased the percent contribution of Waterfowl in the current study.
Increased nesting activity of Aerial Fish Foragers such as terns in the harbors has likely
contributed to the substantial increase in the percent contribution of this bird guild over time. In
addition, large numbers of Brown Pelicans roost at the Ports.
In some cases, the inclusion of both inner and outer harbor areas in more recent surveys has
contributed to a decrease in the percent contribution of guilds that are more associated with one
but not both of these harbor areas. For example, the percent contribution of Shorebirds
declined from 1986–1987 surveys to 2000–2001 surveys; MEC (2002) hypothesized this was
due to limited shorebird habitat being present in the inner harbor. However, Shorebirds
declined again during the current study, likely due to fewer observations of Western Sandpipers
(only 4 were observed in 2007–2008 compared to nearly 300 in 2000–2001; MEC 2002). This
may be due to differences in tidal fluctuations when this species would be present on the Ports’
few mudflat and sandy beach habitats.
Percent composition of Wading/Marsh Birds, which includes herons and egrets, has declined
somewhat since the 1986–1987 surveys (Figure 9.6-3), likely due to inclusion of both inner and
outer harbor areas in more recent surveys and suitable habitat being limited in the inner harbor.
Although most birds were observed resting during the current and previous studies, relatively
more were observed foraging (18.8%) rather than resting (66.4%) during the current study
compared to foraging (10.9%) and resting (76.8%) activities observed in 2000–2001 (MEC
2002). Foraging activity in 2007–2008 also was higher than in 1986–1987 (13%); MEC 1988).
There was a notable increase in courting/nesting activity during the 2007–2008 (2.9%)
compared to 2000–2001 (0.3%) surveys.
Table 9.6-1 provides a historical comparison of the percent contribution of the ten most
abundant species during 2007–2008 compared to historical surveys using yearly averages for
each species relative to total birds counted. Some of the variations in abundance have been
attributed to improvements in waste treatment practices. For example, HEP (1979) attributed a
decrease in the number of gulls between the 1973–1974 and 1978 surveys to the initiation in
the mid 1970s of secondary treatment of sewage and reduction of cannery waste in outer Los
9–12 2008 Biological Surveys of Los Angeles and Long Beach Harbors
April 2010