An Excellent Year in the Gulf of California


Isla Rasa, Mexico. Photo ©Julia WhittyRasa Island, Mexico. Photo © Julia Whitty

I’m finally back from Mexico’s remote Isla Rasa, a tiny outpost in the Gulf of California and one of the most important seabird breeding islands in the world. The island covers a bare 138 acres/56 hectares. Yet it’s home to half a million birds—many more if it’s a good enough year for the birds to produce eggs, incubate them, and hatch their chicks.

Heermann's gulls and a cardón cactus, both endemic to the Gulf of California and the Baja Peninsula. Photo © Julia Whitty.Heermann’s gulls and a cardón cactus, both endemic to the Gulf of California and the Baja Peninsula. Photo © Julia Whitty.

Some 95 percent of all Heermann’s gulls (Larus heermanni) nest on Isla Rasa. These are small, pretty, polite gulls—compared to their much larger Larid relatives.

Heermann’s gull:

  • length 19 inches/48 centimeters

  • wingspan 51 inches/129 centimeters

Great black-backed gull:

  • length 30 inches/76 centimeters

  • wingspan: 65 inches/165 centimeters

Grand Central Station Valley, Isla Rasa, Mexico. Photo © Julia WhittyGrand Central Station Valley, Isla Rasa, Mexico. Photo © Julia Whitty.

In the photo above, you can see the nesting territories of the gulls dotting the island’s valleys. Gulls also nest throughout the rocky hillsides and ridgelines.

Heermann's gull. Photo © Julia Whitty.Heermann’s gull. Photo © Julia Whitty.

In fact Heermann’s gulls nest on every square inch of this sunbaked, windswept island—except where thickets of cholla cactus have taken hold… and where colonies of terns have usurped them.

Elegant tern colony in the midst of Heermann's gulls, Isa Rasa, Mexico. Photo © Julia Whitty.Elegant tern colony in the midst of Heermann’s gulls, Isa Rasa, Mexico. Photo © Julia Whitty.

In the photo above you can see how elegant terns (Thalasseus elegans) have successfully muscled into the territories of gulls in one of the island’s eleven valleys.

Elegant terns, Isla Rasa, Mexico. Photo © Julia Whitty.Elegant terns, Isla Rasa, Mexico. Photo © Julia Whitty.

The terns nest closer together than the gulls. This, and the fact that they move into gull territories en masse and often under cover of night, means they generally get what ground they want—even though they’re smaller birds.

Heermann’s gull:

  • length 19 inches/48 centimeters

  • wingspan 51 inches/129 centimeters

Elegant tern:

  • length 17 inches/43 centimeters

  • wingspan 34 inches/86 centimeters

Heermann's gulls and elegant terns, Isla Rasa, Mexico. Photo ©Julia Whitty.Heermann’s gulls and elegant terns, Isla Rasa, Mexico. Photo © Julia Whitty.

Here’s what the two species look like nesting side-by-side.

You can probably already tell from the numbers of birds in the photos that’s it’s been a very good year so far on the island.

Heermann's gull chick and eggs. Photo ©Julia Whitty.Heermann’s gull chick and eggs. Photo © Julia Whitty.

By the time I left, chicks were hatching everywhere and the whole island was transformed from the calm (in comparison) business of incubating to the furious business of feeding tiny insatiable stomachs.

In a forthcoming Mother Jones article I’ll be writing more about why this year may be the best for the Gulf’s seabirds since the mid-19th century.

HERE ARE THE FACTS:

Our fall fundraising drive is off to a rough start, and we very much need to raise $250,000 in the next couple of weeks. If you value the journalism you get from Mother Jones, please help us do it with a donation today.

As we wrote over the summer, traffic has been down at Mother Jones and a lot of sites with many people thinking news is less important now that Donald Trump is no longer president. But if you're reading this, you're not one of those people, and we're hoping we can rally support from folks like you who really get why our reporting matters right now. And that's how it's always worked: For 45 years now, a relatively small group of readers (compared to everyone we reach) who pitch in from time to time has allowed Mother Jones to do the type of journalism the moment demands and keep it free for everyone else.

Please pitch in with a donation during our fall fundraising drive if you can. We can't afford to come up short, and there's still a long way to go by November 5.

payment methods

ONE MORE QUICK THING:

Our fall fundraising drive is off to a rough start, and we very much need to raise $250,000 in the next couple of weeks. If you value the journalism you get from Mother Jones, please help us do it with a donation today.

As we wrote over the summer, traffic has been down at Mother Jones and a lot of sites with many people thinking news is less important now that Donald Trump is no longer president. But if you're reading this, you're not one of those people, and we're hoping we can rally support from folks like you who really get why our reporting matters right now. And that's how it's always worked: For 45 years now, a relatively small group of readers (compared to everyone we reach) who pitch in from time to time has allowed Mother Jones to do the type of journalism the moment demands and keep it free for everyone else.

Please pitch in with a donation during our fall fundraising drive if you can. We can't afford to come up short, and there's still a long way to go by November 5.

payment methods

We Recommend

Latest

Sign up for our free newsletter

Subscribe to the Mother Jones Daily to have our top stories delivered directly to your inbox.

Get our award-winning magazine

Save big on a full year of investigations, ideas, and insights.

Subscribe

Support our journalism

Help Mother Jones' reporters dig deep with a tax-deductible donation.

Donate