*2.4. Invertebrate Scavenging Experiments*

In summer 2003, we deployed two whole roe deer and eight roe deer body parts (obtained as roadkill animals, divided approximately into quarters for each treatment, with skin and hair in place). The five pairs of carcasses/carcass parts were placed in iron mesh cages (size 1 × 1 × 0.5 m, mesh diameter 2.5 cm) in forest habitat to explore the rate of weight loss by invertebrate scavenging and decomposition while excluding all vertebrate scavengers above the size of a small rodent (Table S3). The experiment was designed to permit weighing the cage with only a minimal vertical lift to avoid losing tissue or dislodging parts of the carcass or the covering. A finer mesh (mesh diameter 1.9 cm) was also installed in the base of the cage, to minimize this issue, ensuring that only decomposition fluids and gasses were lost. However, it is important to be aware of the fact that the weight includes the eventual weight of insect eggs and maggots laid on, or feeding on, the carcass. Our scales were accurate to 100 g. We cannot exclude the possibility that small rodents might have removed some minor amounts of tissue. We used a paired experimental design, where one sample was covered with vegetation and another was left uncovered. Each sample was weighed daily (for a few missing days, we averaged the adjacent days) for 3 weeks following deployment. A four-parameter Weibull model, which represents an asymmetric sinusoidal decay [27], was fitted to the linear stretch of each subset of data by non-linear regression [28]. Three parameters were extracted to describe each curve: (1) day of start of decay (minimum value of the second order derivate of the curve); (2) day of inflection (minimum value of the first order derivate of the curve); (3) day of flattening out (maximum value of the second order derivate of the curve). The values for these three stages were compared using Mann–Whitney U tests.

Analyses were done in R [29], where the Weibull models were run with the add-on package drc [30].
