106 Wigeon vigilance on golf courses
©Wildfowl & Wetlands Trust
Wildfowl
(2013) 63: 105–114
Although it is predicted that waterfowl
should perceive humans as predators (
sensu
Frid & Dill 2002), waterfowl occurring in
habitats experiencing frequent disturbance
stimuli not associated with predation
or other “harm” are likely to respond
differently to human activity (for instance by
habituating to them; Madsen 1995).
Consistent with that observation, it is
increasingly common for wintering and
migrating waterfowl populations, including
American Wigeon
Anas americana
, to use
artificial habitats such as urban parks,
airports and golf courses, suggesting that
individuals selecting these habitats may
become less responsive to human presence
(Blackwell
et al.
2008; Moul & Elliott 1994;
Merola-Zwartjes & DeLong 2005).
Actively feeding waterfowl interrupt
foraging bouts to scan their surroundings,
potentially with greater frequency when
predation risk is elevated (Pöysä 1987). One
measure often used to test the level of
waterfowl response to potential disturbance
stimuli is to measure vigilance behaviour
under different levels of human activity.
Although individuals are vigilant to scan for
potential competitors (Pöysä 1994), or to
monitor family members and mates (Black
et
al.
1992), vigilance is primarily regarded as
an anti-predator behaviour (Caro 2005;
Guillemain
et al.
2007b) and can be used as a
measure of perceived predation risk (Lima
& Dill 1990). In addition to human activity
(Randler 2003; Severcam & Yamac 2011;
Wang
et al.
2011), other factors influence
vigilance behaviour in waterfowl, including:
flock size and density (Lazarus 1978),
position within the flock (Inglis & Lazarus
1981; Black
et al.
1992), pair and family
status (Black & Owen 1989), sexual
differences (Mayhew 1987; Guillemain
et al.
2003), predators (Jacobson & Ugelvik 1992),
distance from water or refuge habitats
(Mayhew & Houston 1989), and presence of
other species (Larsen 1996).
Although factors affecting vigilance
behaviour in waterfowl are generally well
understood, little information exists
quantifying these effects in anthropogenic
habitats where human activity may be high,
but benign, while the benefit in terms of
food intake rates may favour a greater
tolerance of such activity. This study
evaluates the effects of human activity on
the vigilance behaviour of wintering
American Wigeon foraging on a suburban
golf course – a highly human-modified
habitat – whilst also considering other
variables (sex, distance from water, flock size
and position of an individual in the flock)
known from previous studies (Mayhew 1987;
Guillemain
et al
. 2003; Berl & Black 2011) to
influence alert levels in wigeon. Based on the
results of these studies, vigilance by
American Wigeon on suburban golf courses
was predicted to: 1) be higher in males than
females, 2) increase with distance from
water, and 3) decrease with flock size, whilst
levels of individual vigilance would not be
related to 5) presence of humans or 6) levels
of human activity.
Methods
Observations of grazing American Wigeon
were conducted on the Fallbrook Golf Club,
a ~50 ha suburban public golf course,
located 2 km southeast of Fallbrook,
California, USA (33°N, 117°W). The
Fallbrook Golf Club receives high levels of
