Figure 1.
Simplified illustration of the Voronoi-like field generation process.
Here, a 101×101 unit arena is populated with 50 field seeds that are randomly placed on unit cells (a). The nearest seed is calculated for all the cells within the arena (with random allocation if several seeds are equally closest). If a cell possesses at least one neighbour that does not share its nearest seed, it is designated an ‘edge’ cell, whereas cells where all four neighbours share the same nearest seed are designated ‘field’ cells: (b) shows black edge and white field cells for the field seeds given in (a). To calculate wild edge cell availability nest sites are randomly placed on edge cells, and the numbers of edge and field cells are tallied within a given foraging radius of the nest (the area within the grey circle in c).
Figure 2.
Wild forage available within Voronoi-like randomised fields.
Solid black line gives mean values and symbols give the 25%, median and 75% interquartile values for the mean number of visible wild field edge cells (‘visible wild’, panels a, d and g) and the proportion of wild field-edge cells to cultivated field cells within the foraging radius (‘proportion wild’, panels b, e and h), and the ratio of the proportion of field edge cells visible within the foraging distance of the nest compared with the overall proportion of edge to field cells within the simulated arena (‘coverage’, panels c, f and i), where the number of fields seeded (panels a, b, and c), the width of the wild field edge strip (panels d, e, and f), or the radius of the foraging distance around the nest (panels g, h, and i) are systematically altered.
Table 1.
Interactions between the three parameters considered in the Voronoi-like field generation model.
Figure 3.
Results from the British landscape datasets.
These panels show mean proportion (± s.d.) of wild field edges visible according to the foraging radius away from a nest, for (top to bottom) unmanipulated fields, and fields with an extension of 1, 2 and 3 units in their edge margin.
Figure 4.
Increased availability of wild forage as a proportion of the ‘initial’ amount.
Results for fields with edges manipulated by one (bottom), two (middle) or three (top) units, given as a proportion of the non-manipulated edge results.