Why There Are So Many Ravens (And Why I Care)

By   January 23, 2015

Standing in the bed of the Mojave River I feel like an extra in The Birds. In the soft light of a desert sunset 3,000 ravens swirl above. The agitated mass fills the air with alarm calls. Wielding a small laser pointer, to whose light ravens are exquisitely sensitive, my friend Matt and I have put them to flight. We witness a Hitchcockian scene.

Math Lesson 1:

Modern humans transform landscapes. It’s really a quite simple set of equations when considering raven numbers:

The Mojave Desert Before 1940
Hot + Dry + Flat + Shadeless + Food Poor = Very Low Numbers of Ravens

Since 1940 (these changes have increased in area and intensity over time)
Hot
+

Greatly Increased Availability of Water (irrigated cropland, sewage treatment ponds, lawns, parks, golf courses with water hazards, ponds, canals, pools)
+
Greatly Increased Supply of Nesting Sites and Hunting Perches (powerline towers, tall buildings, radio antennas and cell phone towers, highway signs and billboards)
+
Greatly Increased Availability of Shade (planted trees, buildings, intentional shade structures)
+
A Cornucopia (dumpsters, roadkills, landfills, fruit and nut crops, livestock food troughs, pet food bowls, intentional feeding by raven fanciers, a million other opportunities)
=
Vastly Increased Numbers of Ravens (1000% increase between 1975 and 1995 alone)
And so we are awash in highly intelligent, highly opportunistic flying omnivores.

So What?

Fair question. I’ll give you a personal answer. I have spent my professional life with animals whose ancestry stretches back past the Pleistocene, back through the rest of the Cenozoic, back through the cataclysm that snuffed the dinosaurs and all the glorious giant reptiles of the Cretaceous and the Jurassic, all the way back to somewhere around 230 million years ago, deep in the Triassic Age. They are creatures exquisitely refined by surviving on an unpredictable planet.

I don’t know how they’ve done it but desert tortoises, simply by being themselves, have quieted me and slowed me down. They have shown me what it is to be a competent Earthling, living is harmony with their life support system and succeeding by paying very close attention it. I believe in the core of my being that they have lessons to teach us humans if we will but pay attention. If we allow them to slip into oblivion we will have lost any chance to learn these lessons. And they are charmers. I have seen dozens of people fall in love on encountering their first tortoise. I believe the world is a richer and more interesting place with desert tortoises in it.

Ravens love to eat baby tortoises and some have even learned to kill adult tortoises. In the course of my career I have collected hundreds of carcasses of tortoises killed by ravens and watched as the number of juvenile tortoises has declined. In the last two 60-day studies I did in the west Mojave I found zero juveniles but found many tiny carcasses with holes pecked in them.

Math Lesson 2:
More Ravens = Fewer Tortoises

A juvenile Desert tortoise, less than 10 years of age, done in by a raven.

A juvenile Desert tortoise, less than 10 years of age, done in by a raven.

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