The purpose of the study was to test whether surveying dead insects along a roadside could be a method of tracking insect populations over time in a way that: 1) does not require additional insect mortality (many insect monitoring methods require a lot of collecting), 2) does not require a large investment in terms of time, money, or expertise, 3) does not require a lot of processing time or the indefinite maintenance of an insect collection, 4) can be repeated by anyone with a smartphone and an iNaturalist account.
My primary conclusions were that this method could be used to supplement existing insect monitoring methods and may prove useful because of the rapid turn around time from observation to data.
The most interesting thing I observed was that the insect roadkill community on the side of this bridge turned over almost completely from week to week, such that if you sampled for a short time, you would miss huge spikes in population abundance of given insect groups.
I really liked the paper! Itâs a nice demonstration of how productive iNat can be for surveying, and an ingenious way to avoid causing additional arthropod mortality.
I assumed initially that the âJersey barriersâ separated you from the traffic. I was a little alarmed when I later realized that your collections were made in the unprotected road shoulder. I think the safety risks might make it tough to use this approach in many cases.
Itâs true that safety is a major concern for this method! It doesnât seem possible to collect the roadkill without being adjacent to the cars though. The insect debris only accumulates under particular conditions, unfortunately.
Maybe collecting on regular roadside sidewalks with a curb might substantially safer, but I can imagine that the lower traffic volumes and speeds (compared to a highway) might also reduce the collection quantity. Also, requiring paved sidewalks is going to limit a survey mostly to urban and a few suburban areas.
Yes, they donât seem to accumulate on the sidewalks the same way. I tried surveying four other bridges that were also over the river, two of which had sidewalks. Insects only seemed to accumulate where the Jersey barriers were, which were a much more substantial wind barrier than the other fence like barriers on the other bridges (reviewers had me cut the details on the other bridges).
The context in which I see âphoto voucherâ used on bugguide.net means someone photographs an invertebrate alive (or recently deceased) then dissects/keys/analyzes the genetics to determine the species. Since most entomology is done with dead, prepared specimens, it doesnât always translate to photos of living animals.
I use âvouchering systemâ more broadly to refer to the way in which a specimen is vouchered, be that with a collection (like a museum) or via photograph. I think iNat can be considered a kind of vouchering system, given it represents a long term image of an organism coinciding with the date/time/location of the collection.