Carcass persistence time of small wildlife on roads

Description

We measured the persistence time of small-bodied carcasses on road surfaces using amphibians (Pelophylax kl. esculentus) and a variety of small passerine species. Median persistence times for this species were previously estimated at 24 hours, these experiments aim at fine-tuning these estimates by following the disappearance of carcasses in intervals of 2 hours in varied weather, road traffic volume conditions, and carcass position on the road lane. Raw data is available in 'Data.csv' and is organized as follows: day of the experimental trial (day-month) coordinates of the trial observer ID name of the road species (amphibian/passerine) weather conditions (dry day/day with continuous rainfall) daily road traffic volume obtained from local authorities ID of the carcass disappearance interval: lower bound, upper bound (upper bound marked as 'inf' in the case of right-censoring) carcass position on the lane (in tire tracks, outside tire tracks) Example: Amphibian 1 from the D23 road (traffic: 4160 vehicles/day) disappeared between the moment it was placed on the road (t=0) and the first survey (t=2 hours). -- Add_experiment.csv > Continuous following of small passerine disappearance from road, on a dry day at location 'Caluire_Saone'. Carcass ID Position on the lane Carcass bodymass Time elapsed between placement on the road surface and disappearance or end of trial (minutes) Number of vehicles on the lane between placement on the road surface and disappearance or end of trial Right censoring status: 0 = has not disappeared before the end of the trial / 1 = has disappeared from road

Steps to reproduce

We measured the persistence time of small-bodied carcasses on road surfaces using amphibians (Pelophylax kl. esculentus) and a variety of small passerine species. We measured persistence time between March and July 2022 for dry days, October and December 2022 for rainy days. We stored all carcasses at -20°C and thawed them for 24h before the day of the experiment. On each road, we placed N=10 carcasses on the asphalt road surface. We chose the lane using a random number generator so that carcasses could be on road shoulders, in the center of the lane so they would fit in-between the tires of most vehicles, or directly in the path of the left or right vehicle tires. We surveyed the carcasses on foot every two hours to determine whether they had disappeared. We considered a complete removal of a carcass when the observer could no longer detect it when walking on the road. The additional experiment was conducted with the same methodology but with continuous monitoring of the carcasses while counting the number of vehicles passing on the road lane.

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