PARENT SESSION
Wednesday, August 9, 5:00-6:30 pm
Poster Session 15 - Trophic interactions: predator-prey, foraging, and food webs
Exhibit Hall, Ballroom Level, Cook Convention Center

Patch area, substrate depth, and richness effects on the giving-up densities of mourning doves.

Abu Baker, Mohammad^*,1, Brown, Joel¹, ¹ University of Illinois at Chicago, Chicago, Illinois, USA

ABSTRACT- Food harvest by animals represents an interplay between resource characteristics and the animals' ability to respond to these characteristics. We studied foraging by Mourning Doves in patches of sand that varied with respect to initial seed density (2, 4, or 6g of millet), surface area (27, 32, and 36cm in diameter) and sand depth (1.5, 3.0, and 4.5cm deep). Patch use was evaluated in terms of giving-up densities (GUD) and proportion of food harvested (H/IPD). GUDs were also assessed in units of grams of seeds per patch, per unit surface area (GUDAREA), or per unit volume of sand (GUDVOL). GUDs were 52% lower in patches with low depth than high depth. The proportion of food harvested (H/IPD) increased from 39% to 50% in 2g and 6g patches, respectively, revealing the doves' ability to bias search time towards patches with higher IPDs. Effective foraging depth increased with IPD. Tray area had no effect on GUDs or H/IPD. Consequently, GUDAREA was significantly lower in large than small trays (22.3, 27.6 respectively), suggesting that smaller patches hampered the doves' ability to move freely across the surface. On the other hand, tray area and substrate depth had no significant effects on GUDVOL as IPD; hence, doves were able to reach food within a feasible depth of 2.5cm Our results indicate that doves respond to patch properties by biasing feeding efforts towards rich and easy opportunities. The salient properties such as substrate depth and IPD interact in predictable ways to determine resource harvest and foraging effort.

Key words: Foraging, Patch-use, Giving-up-densities