PMC

(Top) Landmark and discriminanda configuration for Protocol 3 (stage 1) in Experiment 1. Two opaque Petri dishes were used as the identical discriminanda and Velcro tabs were glued to the top center of the Petri dishes to hold the landmark in place. This landmark position was called landmark 0 (L0). (Bottom) Landmark and discriminanda configuration for Protocol 3 (stage 2) in Experiment 1. The materials were identical to those used in stage 1 (see A) except that the landmark was placed diagonally at either 1 cm (landmark 1; L1), 2 cm (landmark 2; L2), 3 cm (landmark 3; L3), or 4 cm (landmark 4; L4) away from the discriminandum that covered the reward.

Results for the loss and mean square error (MSE) of landmark localization, landmark visibility, and pose estimation on HyperFace(H) vs. DPLH. (A) Loss of landmark localization. (B) Loss of landmark visibility. (C) Loss of pose estimation. (D) MSE of landmark localization. (E) MSE of landmark visibility. (F) MSE of pose estimation.

Neogonodactylus oerstedii uses a landmark to navigate back to its burrow while foraging. (a) Arena design. A vertical burrow was set into the base of the arena so it was invisible at range (empty circle). A landmark was placed adjacent to the burrow during some experiments (gold-filled star). Food was placed in one of two locations near the centre of the arena (filled circles). (b) Landmark displacement experimental design. Homeward paths were observed when a landmark adjacent to the burrow was displaced to a new location in the arena (gold arrow), while experimental individuals were away foraging. (c) Examples of foraging paths from and to the burrow during the three experimental conditions. Blue lines represent outward paths from the burrow while red lines represent homeward paths before search behaviours were initiated. Grey lines represent homeward paths after search behaviours were initiated. Empty and filled circles represent the location of the burrow and food, respectively. Gold-filled stars represent the location of the landmark. Arrows represent paths of landmark displacements. (d) Data from all homeward paths. Lines and filled circles represent the same as in (c). The grey rectangle represents the track along which the landmark was displaced. The gold rectangle marks the range of locations to which the landmark was displaced during landmark displacement trials. The black tracing in the ‘landmark displaced' group marks the homeward path of an individual on its second run which, after orientating its initial homeward path towards the displaced landmark (in red), it turned back (marked by an asterisk, *) returning to the food location and orientated towards the burrow (in black). (e) Orientations of homeward paths at one-third the beeline distance from the location of the food to the burrow (initial orientations). Each point along the circumference of the circular plot represents the orientation of the homeward path of one individual with respect to the position of the burrow (empty triangle). Grey arcs in the ‘landmark displaced' orientation plots represent the range of the directions of the displaced landmark from at the location of the food. Arrows in each plot represent mean vectors, where arrow angles represent vector angles and arrow lengths represents the strength of orientation . Dashed lines represent 95% confidence intervals. Asterisks (*) denote a significant difference between groups (p < 0.05). ‘Landmark absent' data were obtained from Patel & Cronin []. (f) Homeward path orientations of groups same as in (e) measured immediately before search behaviours were initiated (terminal home vector orientations). (g) Straightness of homeward paths from the location of food to the burrow. Larger path straightness values indicate straighter paths with a value of one being a completely straight path from the food location to the burrow (a beeline path). Bars represent medians, boxes indicate lower and upper quartiles, and whiskers show sample minima and maxima. Asterisks indicate significant differences in path straightness between groups (p ≤ 0.05; landmark absent: n = 13, landmark fixed: n = 13, landmark displaced: n = 10).

Landmark error comparisons – manual intra‐observer error is the average distance between landmark locations from landmark placement trials 1 and 2 across a representative subset of 100 samples. Average intra‐observer error is compared to the average distances between (A) manual and one‐level landmark coordinates, (B) manual and two‐level landmark coordinates and (C) one‐level and two‐level landmark coordinates for each landmark across all samples. Landmarks showing relatively high placement error are identified by ID, as defined in Fig. .