New Jersey Wildlife: Vultures, nature's cleanup crew

John Parke By John Parke Hunterdon County Democrat
on November 19, 2013 at 7:00 PM, updated November 19, 2013 at 7:01 PM

New Jersey is the most densely populated state in the nation and with a lot of people comes a lot of vehicular traffic.  With its 38,122 miles of roads it is almost a guarantee that while traveling in New Jersey you will encounter roadkill.  In 2010, a study was done by an insurance firm that conservatively estimated that over 30,800 deer were hit per year by motor vehicles in the Garden State.  

This number obviously does not include other animals such as the many raccoons, opossums, squirrels, rabbits, birds, reptiles and amphibians that meet there demise trying to cross New Jersey’s busy roadways. With so many dead animals lying on roadways, one has to wonder, is there anything that can utilize this carnage?  Enter the vultures.

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In New Jersey there are two different native vulture species: turkey vultures and black vultures. The turkey vulture is a historic resident of New Jersey whereas the black vulture is more of a recent immigrant from the southern US that now persists in the state throughout the year and is expanding its range northward.

Vultures play a very important role in an ecosystem, specifically they specialize in feeding on the dead.  This role of a scavenger is one of the most important yet under-appreciated ecosystem services of any bird group.  Because vultures feed by scavenging they can rapidly dispose of decomposing carcasses whereupon they provide nutrient cycling and help in reducing the risk of contamination by disease producing pathogens such as bacteria, virus and fungus.

Vultures have evolved specialized body parts for the gruesome job of scavenging on carrion, dead animals.  For instance, vultures have extremely good eyesight to see a carcass from high altitudes and they also have a highly developed sense of smell compared with other bird species. In fact, vultures can smell carrion from over a mile away. The turkey vulture in particular has the largest olfactory system of all birds.

Once prey is detected, a vulture will use its very strong beak to pull and tear flesh from the body and attempt to open a pathway into body cavity.  With its bald head a vulture can then reach inside the body cavity of a dead animal and not have pieces of body adhere to the skin as it would to feathers. Finally, vultures have highly acidic stomach liquids and urine.  The acidic stomach liquid allows for the digestion of the raw flesh. However as their primary defense mechanism, when threatened vultures will regurgitate its stomach contents, including the rancid acidic stomach liquid to deter and confuse an intruder.   A vulture will also urinate on its legs whereupon the acidic urine kills any bacteria that has built up on the bird from manipulating carrion.  

Vultures are very adaptable and exhibit complex behavior. They are social animals and will often form large roosts and loafing areas. Roosts sites however can change each night. Groups of perched vultures are called a “wake."  In the early morning hours after a cool or rainy night in order to increase their body temperature or dry off wings vultures like to “sunbath” with their wings spread out in a “horaltic pose."
 Vultures will also defecate on their feet in the hot summer months to cool them off.   When a group of vultures is seen together flying it is called a "kettle." This term is related to the appearance of swirling water boiling in a pot, hence a “kettle."  

Researchers indicate that vultures have been documented to rise to as high as 20,000 feet, soar for hours without flapping their wings and can travel at up to 200 miles in a day.   In spite of their large size, they only weigh between 2-4 pounds.  A long lived bird the average life of a turkey vulture is about 16 years of age and black vultures can be up to 25 years.

Populations of both species have increased in abundance and range in the past 30 years. These increases may continue into the future particularly since a recent study of roadkill by the University of California indicated that:  “The number of animals killed by vehicles in the United States is estimated at a million per day.”


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