Francisco Vara-Orta writes,
"Eager to reduce the neighborhood pigeon population and the mess that comes with it, Hollywood residents appear ready to try a new birth control method on their wild birds.
"Beginning within the next couple of months, a substance called OvoControl P will be placed in kibble in new rooftop feeders, say residents and state and local officials. The substance, which interferes with egg development, generally is viewed as a humane way to lower the birthrate of the birds, which many residents consider a
Not answered in the story is what this substance does to hawks who eat affected pigeons and what it might do to non-target birds who will certainly also ingest the stuff directly.
OvoControl developers say the risk is negligible: "Fortunately, the chemistry of the active ingredient assures that there is an extraordinarily low risk of any effect on a raptor. To have an effect, the bird MUST consume the bait – raptors enjoy fresh meat and fish, not OvoControl bait. Once OvoControl is digested and absorbed, it is no longer biologically available to another bird. There is effectively no risk of secondary toxicity."
...Except for hawks who eat stomach contents, which they occasionally do. On the other question they say:
"All avians are considered sensitive to the product. OvoControl has therefore been designed to limit non-target exposure to birds. There are five techniques employed:
- The bait is relatively large, suitable for a pigeon but not to the average songbird. The bait has low oil content.
- The bait is fed on a restricted basis—roughly 5gm/bird, or roughly 15% of the pigeon’s daily dry matter intake—at the crack of dawn, in the general vicinity of the overnighting birds. Experience shows that once the pigeons are habituated to the bait, it is consumed in 15 minutes or less leaving little opportunity for non-target feeding.
- Pigeons are flocking birds. Feeders are placed on rooftops where the risk of non-target exposure is limited.
- A daily dose is required during the breeding season. It is possible that a non-target receives a dose from time-to-time, but periodic observation by the applicator ensures that OvoControl is reaching the target population.
- Raptors will not consume bread based bait.
A lot of variables and qualifiers there. But given the chemical wears off and must be continually used, it is probably mild and not much of a threat except to pigeon family values. However, it sounds like a gold mine for the drug's producers!