9/4/16 – A stochastic event is a random, unpredictable event. As a wildlife biologist we learned about stochastic events as one of many possible causes for death, and we try to determine how much of an impact these events will have on population viability. A classic example given is a severe weather event, or a roost tree being struck by lightning. Stochastic events can also play a role in gene expression, or species dispersal. Usually a breeding population is not established and these individuals are considered waifs, stranded in a strange location.
Hurricane Hermine provided two examples of a stochastic event:
First, as the rains and cold air swept across North Carolina I noticed a Bumble bee (Bombus sp.) that had gotten caught out as the weather turned. She was wet and in cold-shock, barely able to move. Since she was firmly holding on to a flower of chives (Allium sp.), I simply cut the flower and carried her by the stem.
I lined an empty plastic salad box with some napkins to help wick away moisture from her body, and I offered a dab of honey. I placed the container near a lamp to slowly warm her. It did not take long before she was grooming herself and fanning her wings. She was revived, but we still had another 12 hours of rain in the forecast, so I wrapped a towel around the container to deter her from flying into the clear sides and I set her in a quiet place. Soon she had crawled under the layers of the napkin, where I thought she would sleep, but she came back out later to have a meal of the honey.
The following day we had warming temperatures and sunshine, so I released her. Hopefully she will go on with her important work of pollinating flowers. I wonder how many bees and other pollinators were killed by this stochastic event? If you are interested in helping researchers try to save the declining bumble bee species or you just want to learn some more, check out Bumble Bee Watch.
The second example comes from this story of a not so unusual event: thousands of birds got caught in Hurricane Hermine’s eye, and are being ‘transported’ along with the storm as it moves up the east coast. Some of these birds will be killed directly by the storm, some will be relatively unharmed. Birds that survive will need to find food and how much time they have to do that will vary. There are unique opportunities for bird watching after a hurricane blows through, but be sure to always be mindful of flooding and other weather hazards when trying to spot a rare bird blown in by a storm. While birds evolved to migrate with hurricane season, human altercation of coastal habitat can increase the effects of severe weather. Learn more about hurricanes and migrating birds at this Cornell Lab site and on this Audubon page.