Figure 2. Scoring in the nest building test.

Scoring was performed according to a previously published assessment scheme (Table 1; Deacon, 2006) using grades ranging from 1 (very poor) to 5 (optimal). Examples of nests reaching scores of 2 (A), 3 (B), 4 (C) and 5 (D) are shown. For all of these nests, the vote of two independent evaluators was unanimous. Note that grade 1 would correspond to an untouched nestlet. However, no animal graded lower than a score of 2 in our test cohort.