The unintentional side effects of poison

Common Raven

Many local businesses have resorted to using poison to control pest species such as Pigeons and Rodents.   The reasons for doing so vary from loss of property and profit, to health concerns, and droppings leaving an unsightly mess on the sides of the buildings and rooftops.   However, the use of poison to control these pest species has a very unfortunate side effect that very few people mention, witness or even understand.


The poison that is used does not just target and kill the intended pest species.  In fact it can, and does act like a disease, which spreads to include other species.  Take the Raven for example.  Not only do local Ravens hunt Pigeons for food in winter, thus helping to control their population, they also eat carrion.  Their doing so helps prevent the spread of disease, but has now come with deadly consequence.  Just lately I was told by a friend that the body of a Raven had been found in a Garden Center without wounds, or other indication of injury that may have caused it's death, and this was not the first time this year.  While the Garden center is now closed, they still store seed and so, still implement pest control measures.

Peregrine

A couple of days ago I came across this little bird, in the photo below, outside of a business, near that same garden center.  It was a very sad species introduction for me.  As you can see there are no wounds, there is also no window nearby, ruling out a window strike.  My best guess, since this is a seed eating species, is that he got into some of the poisoned seed left out for the Pigeons on the rooftop.  

Common Redpoll male

Carrion eating species of birds and finches are not the only species to be affected.  Some of the poison that is left out for pest species to consume, is slow acting and creates horrible suffering.  Once the poison takes effect, the creature cannot move very fast or very far.  I have seen this many times, when I worked in a warehouse that stored and sold grain and seed products.  The result is that the poisoned creature can often be found out in the open somewhere between the location of the poison and a place of safety.  This leaves them vulnerable to predators such as the Merlin below, a Peregrine Falcon, an Owl or even a pet cat.

Family cat

While the predators may then instantly relieve their suffering, they in turn will suffer and die, when the Rodent or Pigeon is consumed.  Their bodies, if not left to decompose, will eventually be discovered and consumed by one of the many carrion eating species of wildlife.  If they do not consume the dead or dying creature themselves, as might be the case during the breeding season, then an Owl, Raven, or Merlin will feed the poisoned pest species to their mate, or their young, killing them instead.

Merlin

While I know that this was not intentional on the part of the decision makers involved, the use of poison as pest control measure has created a very bad, very indiscriminate cycle of death for many wildlife species that needs to be stopped.   However, the sad truth is, this local community isn't the only one to use poison to control pest species populations and eliminate health threats.  Poison has been used for many years by communities the world over.  Are there alternatives?  More in another post.

Susan