The Stunning Decline of Birds
- A noted bird conservation director and analyst said that of the birds surveyed in a recent national study, “about half are in decline and of these half are in significant decline.”
- The most cited cause of the declining bird population is loss of habitat due to urbanization, conversion of land to agriculture, and the ongoing widespread use of pesticides. While it’s generally agreed that cats are the second leading cause of declining bird population worldwide, bird/window and bird/vehicle collisions are substantial and are estimated to number in the billions. New energy saving developments such as solar farms and wind turbines have caused additional and significant stress on bird populations.
- Estimates certainly vary, but most indicate that cats kill in the area of one billion plus birds annually – just in the United States.
- A University of Georgia study showed that cats bring home only 23% of their kills, calling into question whether previous statistics might have been significantly underestimated.
- At the height of the “Plume Boom” in the early part of the 20th century the business of killing birds for the millinery trade was practiced on a large scale, involving the deaths of hundreds of millions of birds from throughout the world to be used for fashion.
Bird Vision
- It wasn’t until the 1970’s that researchers discovered birds have UV receptors in their retinas and see ultra-violet light as different colors that humans do not perceive.
- Bird’s eyes have 4 cones; red, green, blue and ultra-violet. Humans’ eyes have only three; red, green and blue.
- Each cone in a bird’s eye contains a colored oil droplet that no longer exists in mammals. This oil increases the variety of color that a bird sees.
- In technical terms, humans only see light wavelengths from 400 to 700 nanometers whereas birds, see in the UV spectrum beginning below 400 nanometers.
- The colors that humans see in bird plumage can vary dramatically from the colors birds see and where humans see no colors in bird plumage, birds can see vivid colors. Research shows this visual ability plays a major role in courtship and survival. Many fruits and berries reflect UV light.
- Finnish researchers from the University of Turku discovered that small rodents leave trails of UV reflecting urine which makes them highly visible to Kestrels soaring over open fields.
The Cat Factor
- In New Zealand, a University of Otago study showed that bells on cat collars can reduce bird kills up to 50%. Other studies show that some cats actually adapt their stalking motions to neutralize and silence the bell.
- There are an estimated 90 million pet cats in the U.S. with only about 35% kept exclusively indoors. The feral cat population ranges from 60 to 100 million and impacts nearly every city in the country.
- A University of Nebraska study states that cats have been responsible for the extinction of 33 bird species worldwide, largely on islands where cats were introduced, and in one case by a lighthouse keeper’s pet cat which took out an indigenous species that ground nested.
- One study showed that in a group of controlled observed cats, a declawed cat actually had the highest kill rate of birds.
- As many birds as cats destroy, they are a distant second to the number of small mammals and reptiles that fall victim.
- More than 7 animals per minute are killed in shelters unnecessarily adding up to more than 9,000 healthy and treatable animals per day! Kittens under 8 weeks old comprise the top of the at risk shelter population for euthanasia