Ripley’s K for all the years, along with 1000 random allocations (in grey).

<p>Ripley’s K is a measure of clustering across a range of spatial scales, transformed here such that values above zero represent clustered distributions and values below zero are uniform distributions <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097809#pone.0097809-Haase1" target="_blank">[20]</a>. The ordinate effectively represents the average number of nests found within a random circle of the radius on the abscissa. The slightly positive slope of the random allocations is a consequence of the three empty hectares at the corner of the plot.