Video 3 from Plant–animal worms round themselves up in circular mills on the beach

Video of twin circular mill number 3 up the beach from boulder H (figures 2<i>c</i>) at 2 x normal speed

Experimental protocols.

<p>Total number of colonies used in the experiment (<i>n</i>) and in the final data analysis (<i>n</i>'); quality of the old nest; and number and quality of available nest sites during exploration and emigration for each experiment and each treatment (when applicable). For the emigration phase, it is indicated whether new nest sites are familiar (F) or unfamiliar (U).</p

Experimental design.

<p>Top view of the exploration arena consisting of one large, central dish; two small, intermediate dishes; and two small, peripheral dishes. Adjacent dishes were connected by tunnels for the ants to walk through. Conspicuous landmarks (black shapes) were used to help ants orientate inside the arena. Colonies housed in their old nest (ON) were positioned in the middle of the central dish. One or two available new nest sites (N1 and N2) were positioned in the peripheral dishes either at the onset of exploration (familiar nests) or at the onset of emigration (unfamiliar nests). The position of new nest sites (right or left) was pseudo-randomized between colonies.</p

Video 1 from Plant–animal worms round themselves up in circular mills on the beach

Video of circular mill number 1 on the beach near boulder D (figures 2<i>a</i>) at 2 x normal speed

Prior experience and speed-accuracy trade-off (experiment 3), final state.

<p>(<b>A</b>) Number of colonies split (S, hashed bars) or having chosen the good (G, white bars) or mediocre nest (M, black bars) 24 hours after emigration onset. Nest choice patterns were compared between treatments using Fisher-Freeman-Halton's exact test and nest preference was tested within each treatment using exact binomial tests (ns: non-significant; ****: <i>p</i><0.001). (<b>B</b>) Reunification time for informed (light grey, n = 18) and naïve (dark grey, n = 18) colonies. Bars and whiskers represent the means and standard errors, respectively. The effect of treatment on reunification time was tested using GLMM (no data transformation).</p

Video 2 from Plant–animal worms round themselves up in circular mills on the beach

Video of circular mill number 2 on the beach near boulder F (figures 2<i>b</i>) at 2 x normal speed

Prior experience and emigration speed (experiment 1).

<p>(<b>A–D</b>) Emigration data for informed (Inf., light grey, n = 24) and naïve (dark grey, n = 24) colonies emigrating to a single good nest site (experiment 1). Bars and whiskers represent the means and standard errors, respectively (A–B, D); full squares, rectangles, whiskers and open circles represent the median, interquartile range, 1.5 x interquartile range and outliers, respectively (C). (<b>A</b>) Discovery, assessment, transport and emigration times. The effect of treatment on each variable was tested using GLMM (no data transformation). (<b>B</b>) Crossing times of intermediate dishes leading either to the new nest site or to the dead-end. Same letters indicate no statistical differences, whereas different letters indicate significant statistical differences (<i>p</i><0.05) in LSD post-hoc comparisons (GLMM, interaction treatment/direction: <i>p</i> = 0.059; no data transformation). (<b>C</b>) Number of successful forward tandem runs to the new nest site (Wilcoxon matched-pairs test). (<b>D</b>) Quorum thresholds used to switch to transport. The effect of treatment on quorum threshold was tested using GLMM (no data transformation). (<b>E</b>) Relationships between the number of ants in the familiar nest at the onset of emigration and, respectively, the quorum threshold (left) or the assessment time (right) for informed colonies (n = 24). Linear regression shows that these relationships are best described by the following equations: (i) Quorum Threshold  = 2.422+1.059 x No. of ants, <i>r²</i> = 0.82, <i>p</i><0.001; and (ii) Assessment time  = 5.3+0.171 x No. of ants, <i>r²</i> = 0.048, <i>p</i> = 0.301.</p

Prior experience, nest choice and cohesiveness (experiment 2).

<p>Emigration data for informed (light grey, n = 33) and naïve (dark grey, n = 33) colonies emigrating to one familiar (F) and one unfamiliar (U) good nests or to two unfamiliar good nests (U1 and U2), respectively (experiment 2). Bars and whiskers represent the means and standard errors, respectively. (<b>A</b>) Discovery, assessment, transport and emigration times. <i>P-</i>values are given for the effect of nest site (familiar/unfamiliar) on discovery, assessment and transport times, and the effect of treatment (naïve/informed) on emigration time (GLMM; discovery time was log-transformed). Same letters indicate no statistical differences, whereas different letters indicate significant statistical differences (<i>p</i><0.05) in LSD post-hoc comparisons. (<b>B</b>) Number of successful forward tandem runs towards new nest sites. Same letters indicate no statistical differences, whereas different letters indicate significant statistical differences (<i>p</i><0.05) in LSD post-hoc comparisons (GLMM; effect of nest: <i>p</i><0.005; no data transformation). (<b>C</b>) Choosiness and Cohesiveness indexes. Choosiness was calculated as the proportion of items in the familiar nest (informed colonies) or in unfamiliar nest 1 (naïve colonies). <i>P</i>-values are given for the effect of treatment on both variables (GLMM; no data transformation). The broken line over choosiness – set at 0.5 – represents expectations under the hypothesis of random choice between both nests (*****: <i>p</i><0.001 in one-sample Wilcoxon test for non-normal data; ns: non-significant in one-sample t-test for normal data).</p

Cross tabulation for effect of manipulation on final nest choice.

<p>Best choice: chose the better new nest, or split between the two new nests; moderate: chose the worse new nest; impaired: remained in starting nest or split between starting and worse new nests (nest destruction from previously published data).</p><p>Cross tabulation for effect of manipulation on final nest choice.</p

The range of nest types used in the experiment: (a) clear cover, 1mm wall height, 4mm entrance width; (b) red filter cover, 2mm wall height, 4mm entrance width; (c) red filter cover, 2mm wall height, 1mm entrance width; (d) clear cover, 1mm wall height, 4mm entrance width, acetate film with holes for ant removal and second acetate layer to act as a cover; (e) clear cover, 1.8mm wall height, 4mm entrance width; (f) red filter cover, 1.8mm wall height, 2mm entrance width. (g) Experimental arena, starting nests were of poor quality and were not destroyed, allowing voluntary emigrations to occur.

<p>A similar arena was used for the nest destruction treatment, measuring 800x165mm [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141012#pone.0141012.ref015" target="_blank">15</a>].</p