#Flock meaning driver#

For example, the attack success threshold may have been as low as 40, and optimum group size may not have been reached by a group size of 80. Some of the threshold estimates were uncertain. Advantages of increasing group size from the attack success rate function, however, were still substantial, even up to group sizes of 70, and we found a preference for flocks up until at least 80, as shown by the continuing increase (or peak) in number of birds using flocks up to about 80 in Fig.

#Flock meaning driver#

The strength of selection for the dilution effect above flock sizes of about 30 was minimal predicting few larger flocks if this were the main driver of group size (assuming no other advantages of flocking), and this is shown by the reduction in the strength of increase in the relationship shown in Fig. Either way, redshanks clearly preferred large flock sizes up to around 80-100, and the group sizes most frequently used by birds were therefore closest to those that might be predicted from the overall individual predation risk relationship and the attack success rate relationship. First, the quadratic fit suggests an optimum flock size of about 80, but the logarithmic relationship sug- gests redshanks avoid small flocks (less than 30) but still attempt to form large flocks at least up until 100 (the maxi- mum flock size we included). This relationship between the preferred flock size and population size has two possible interpretations. Redshanks were found most commonly in large flocks, although there was little increase in the frequency with which redshanks favoured larger flocks above a flock size of about 30 (see Fig. continued to increase group size as population size increased, both independently of attack rate and beyond the threshold predicted by both the dilution effect and the individual risk of being killed per attack (see Fig.