So often we hear about barn owls and their status as the sentinel species in the continual monitoring of rodenticide residues in the environment.
But how is it that these residues get from us, to them?
A paper by D.E. Glue titled Prey taken by the Barn Owl in England and Wales in 2009 highlighted that the majority of prey animals taken by Barn Owls are not the species we in the Pest Industry focus on when it comes to chemical interventions.
With this in mind, the Wade Environmental team decided to collect Barn Owl pellets from a farm in Hampshire and dissect the pellets to ascertain the abundance of small mammal species found.
The data collected from the WE study showed a similar trend towards the majority of a Barn Owls diets consisting of non-target small mammal species, specifically field mice and voles.
Although it must be kept in mind that due to the size discrepancy between Brown Rats and Voles the DE. Glue paper noted that by weight Brown Rats could account for a larger proportion of diet than their frequency might belay, they still accounted for less than half of the biomass consumed.
Even with that consideration however this does draw a worrying thought, and that is that the mechanism by which residues find their way into the food chain is not through the intentional poisoning of pest species, but the unintentional or coincidental poisoning of non-target species.
Therefore let this be a reminder to ensure you fill out an Environmental Risk Assessment for every job, as well as revisiting these forms each time you return to sites.
Want to see more like this? Sign up for the latest Wade Environmental newsletter.