VULNERABILITY OF SCOTTISH SEABIRDS TO OFFSHORE WIND

3.3 Percentage of time flying (Factor 3)

This factor is considered to indicate risk of collision because seabirds that spend more time flying while at sea are more likely to be at risk of collision (all else being equal). Where available, scores were taken from Garthe and H◘ppop (2004), adjusted where apprtopriate according to more recent research publications. For other species, scores were calculated from data on activity budgets following the procedure outlined by Garthe and H◘ppop (2004). Species were scored 1 if 0-20% of time at sea was spent in flight, score 2 if 21-40% was spent flying, score 3 if 41-60% was spent flying, score 4 if 61-80% was spent flying, and score 5 if 81-100% was spent flying (Table 7). In the last few years, data logger information is starting to provide detailed information on at-sea activity of seabirds. For example, Kotzerka et al. (2010) reported that black-legged kittiwakes spent 35% of foraging trips engaged in sustained directional flight, and much of the remaining time in localised areas searching for food. There may be quite considerable variation in time spent flying between seasons, with breeding seabirds rearing chicks flying more than nonbreeders in winter. At present there is too little data on this to be able to provide seasonally separated scores.

Table 7. Percentage of time flying scores