Strike

February 26, 2024

It has been warm over the last several days (+70F/+20C) and Melissa has taken to keeping the patio doors open to allow the dogs free access to the yard and house.  While we do have a “doggie door” in the kitchen, it was installed for a toy poodle (Canis familiaris – all domestic dogs) and would hardly provide access for our 75 to 85 pound (34 to 38.5 kg) pups, although Loki does try and stick his head and front feet through the door.  While working this morning melissa noticed two house sparrows (Passer domesticus) had taken advantage of the open door and decided to check out the succulents stored on the porch.  Melissa quickly shut the kitchen door, and then chased the sparrows back outside, then closed the outside door to prevent more birds coming inside.  After sitting back at her work chair, she heard a loud bang as a Eurasian collared dove (Columba decaocto) struck the patio glass.  The bird fluttered away, unhurt but obviously dazed.  I found this ironic as opening my browser it featured another article on the apparent bird strike that killed Flaco last week. 

When I looked online, I found one of the major problems in the interaction between humans and birds is the occurrence of window strikes.  Most strikes are associated with tall skyscrapers with reflective windows, but nearly 50% of bird collisions occur at homes.  It is estimated between 365 and 988 million birds are killed annually in the US by building strikes.  Approximately 56% of these deaths occur at low-rise buildings, 44% at residences, and only 1% at high-rise buildings.  This is second only to mortality from feral and free-ranging domestic cats when considering types of human-caused bird mortality.  The problem exists because birds cannot see glass and only see the reflections of their surroundings or the interior of a home or building if the light inside is brighter than outside.  Birds’ bodies are fragile, and they seldom survive a first collision to learn from their mistakes.  Even birds that can fly away after a collision may die from internal injuries or from predation due to their wounded state.  Birds are especially vulnerable when seeking escape cover after being frightened by predators (real or perceived) or by loud noises.  Window strikes by males their reflection to be a rival for territory or a mate are usually more of an annoyance to the homeowner than a threat to the bird.

One suggestion to avoid window strikes is to make the glass doors and windows more visible.  When you put something on the outside of the window it can make it more visible to birds.  The Cornell Lab of Ornithology and the Bird Collisions Program of the American Bird Conservancy provide a few suggestions.  Creating patterns or designs on windows help break up reflections and can appear as a barrier to birds.  However, these markings must be applied to the outside of windows as any reflections on the outside of the window may obscure markings on the inside.  You should also use white or light colors to maximize contrast and visibility.  The markings should be visible from at least 10 feet (3 m) away to give birds time to see them and react.  Grids of dots or lines are very effective if they are placed no more than 2 inches (5 cm) apart over the entire window surface.  Wider spacing will create apparent gaps that smaller birds may still try to fly through.  Stripes should be at least one-eighth inch (.5 cm) wide, and dots at least one-quarter inch (1 cm) in diameter and bigger is better.  Hmm, I just installed large picture windows on the porch and bay to let in the light.

THOUGHTS:  There are commercially available films that can stop strikes when applied to the outside of a window that appear solid from the outside but cannot be seen when looking out.  Many of these products and do-it-yourself ideas are discussed on the American Bird Conservancy’s website.  Although the male eastern bluebird (Sialia sialis) has attacked the window, the collard dove was the first actual strike.  There are always decisions and tradeoffs with any human improvements .  Act for all.  Change is coming and it starts with you.