Table 1. Categorical values used to rate the overall reaction of gulls to auditory and visual stimuli.

Response Value*	Description of Response
0	No response
1	Initial increase in vigilance followed by relaxation during 30 sec period
2	Increased vigilance for entire 30 sec period: neck slightly raised, casual scanning for threats, does not interrupt activities like panting
3	Extremely vigilant for entire 30 sec period: neck fully outstretched, rapid scanning for threats, activities like panting often interrupted, use of ‘kek-kek’ calls
4	Use of ‘yeow’ alarm call
5	Stood up off eggs
6	Movement within 3 m of nest
7	Movement beyond 3 m of nest, including flight

^*Higher values represent more energy-intensive responses and may also include behaviors described under lower response values.