Saw Mill River Audubon
Connecting People and Nature Since 1953
  • Home
  • SMRA web page
  • SMRA FaceBook page
  • Send email to SMRA
Turkey Vulture

Birding

Secret Life of Croton’s “Carrion Crows”

SMRA January 8, 2020

You don’t have to be a birder to notice the huge flocks—sometimes numbering 100 or more—of big, dark birds looming over downtown Croton-on-Hudson this fall and winter. Or to know what they are: vultures (often nicknamed “carrion crows” or “buzzards”), those notorious scavengers of road kill and other carcasses that seem to be increasing in number every year around these parts.

Their growing presence is all a glance will tell you about the local vultures, and for many people, that’s all they need to know. But—as with so much in the natural world—if you take a moment to look closer, you’ll see that the story of these big birds is far more complicated, full of surprising twists and turns.

First of all, Croton doesn’t simply have “vultures”: It has two different kinds, Turkey and Black. They’re actually pretty easy to tell apart. The more common TVs, brown-black in plumage, have long wings that slant upwards, forming a V, as they tilt buoyantly in even a slight breeze. BVs, a more recent arrival in our area, are darker (with silver-white patches at their wingtips), slightly smaller and squatter, and have a heavier flight. They flap much more frequently than their cousins.

And while they both have bare, featherless heads, Turkey Vultures’ are pink and Black Vultures’ grey-black. (Bare heads make for less mess when they’re delving deep in a carcass for succulent morsels—and aren’t you glad you know that now?)

But there are other, more fascinating differences between the species. Turns out they also boast dramatically different behavior, feeding habits, and dominance.

For example: Even though we see the two species soaring and roosting together, they don’t actually get along that well. Since Turkey Vultures are larger on average, a single individual can dominate a single Black at a feeding site. But Black Vultures have a way to counteract that size disadvantage: They team up. They form a pack…and a pack of BVs can almost always drive a lesser number of TVs away.

Secondly, while Turkey Vultures depend almost entirely on carcasses for their food (only rarely killing a sick or young animal), Black Vultures hunt live prey much more frequently. The pack mentality, more akin to wolves or lions than other birds, even allows them to bring down mammals such as skunks, calves, and young pigs.

But perhaps the most striking difference between the two species is that they use two entirely different senses to locate carrion.

Black Vultures, like most day-flying predatory birds, rely on their keen eyesight. When foraging or hunting, they soar (and flap) high in the sky, scanning the ground below.

Turkey Vultures, however, use a far rarer—almost unheard-of—method: They employ their sense of smell. Recent research has shown that the vultures possess an olfactory bulb (an area of the brain that processes odors) far larger than that of Black Vultures. In fact, their olfactory bulbs are larger as a proportion of brain volume than those of nearly 150 other bird species studied.

This and other anatomical differences allow Turkey Vultures to recognize ethyl mercaptan, a chemical produced when a dead mammal has begun to decay. The vultures can detect this chemical sooner after death than any other carrion-eater, making them most often the first to the feast.

The same adaptations mean that foraging Turkey Vultures tend to fly low over the canopy, which gives them a better chance of catching that first whiff of ethyl mercaptan. And the Black Vultures? While they soar higher, scanning the ground with their keen eyes, they’re also keeping a close eye on their cousins flying closer to the ground. When a Turkey Vulture locates the carcass first and descends, down swoop the BVs as well. (And then sometimes attack in a pack to drive away the bird that first located the meal.)

Perched on their rooftops and tree limbs, Croton’s carrion crows seem little more than a group of silent, hulking nuisances. But like almost everything in nature, they actually paint an extraordinary portrait of adaptation, competition, and survival. One that rewards a closer look.

Joe Wallace

Related Posts

Shrike-Rappaport-ver2

Birding /

The Sentinel Butcher is Watching

a-bobcat-in-the-wild

Birding /

The Prowler in the Backyard

Winter Wren

Birding /

Wintersong

‹ Evolution’s Outreach Program › Activism in the Age of Climate Grief

Recent Posts

  • The Sentinel Butcher is Watching
  • The Prowler in the Backyard
  • Wintersong
  • Tumult Season
  • Still Magical After All These Years

Recent Comments

  • SMRA on If You Plant It
  • Seasonal Focus: Winter Finches – Saw Mill River Audubon on Winter Events!
  • Message from our Board President – Saw Mill River Audubon on Issue Alert: Hudson River Proposed Anchorage
  • Message from our Board President – Saw Mill River Audubon on SMRA Explores the Southwest!

Archives

  • February 2023
  • January 2023
  • October 2022
  • July 2022
  • June 2022
  • May 2022
  • March 2022
  • January 2022
  • December 2021
  • November 2021
  • October 2021
  • September 2021
  • August 2021
  • July 2021
  • June 2021
  • May 2021
  • April 2021
  • March 2021
  • January 2021
  • December 2020
  • November 2020
  • October 2020
  • September 2020
  • August 2020
  • July 2020
  • June 2020
  • May 2020
  • April 2020
  • March 2020
  • February 2020
  • January 2020
  • December 2019
  • November 2019
  • October 2019
  • September 2019
  • August 2019
  • July 2019
  • February 2019
  • September 2018
  • September 2017
  • August 2017
  • June 2017
  • April 2017
  • March 2017
  • January 2017
  • December 2016
  • November 2016

Categories

  • About SMRA
  • Advocacy
  • Backyard Habitats
  • Birding
  • Climate Change
  • Ecotourism
  • Education
  • Field Trips
  • Native Plants
  • Programs
  • Public Programs
  • Sanctuaries
  • SMRA
  • Special Events

Meta

  • Log in
  • Entries feed
  • Comments feed
  • WordPress.org

Back to Top

© Saw Mill River Audubon 2023
Powered by WordPress • Themify WordPress Themes