To call someone a cabeza de chorlito in Spanish is equivalent to calling that person a birdbrain in English. But how did the poor little chorlito (plover) end up with a reputation for not being the sharpest needle on the cactus? Recently I found out.
I had been invited to the shores of Atotonilco Lagoon — a Ramsar (protected) wetland located alongside the town of Villa Corona, located 40 kilometers southwest of Guadalajara — by a group of volunteers who were trying to remedy a problem that the snowy plover, Charadrius nivosus or chorlito nevado in Spanish, is hopelessly stuck with.
At the lagoon, nature photographer Ernesto Sánchez explained the situation to me: “Unlike other birds that hide their nests in tall grass or trees, the plover, which is on the list of endangered species, lays its eggs on a flat spot on the beach, out in the open and its nest consists of nothing more than a slight depression in the sand or mud. For a chorlito, even an animal footprint will do as a nest.
“So, here on the shores of the Atotonilco Lagoon, those eggs are left not only to the mercy of predators like crows and possums, but are also in danger of being accidentally crushed by human heels, cows’ hooves or the wheels of cars being driven aimlessly up and down the beach.”
“¡Cabezas de chorlito!” I couldn’t help exclaiming. “Why do these birds lay their eggs out in the open?” I asked the leader of the project, biologist Said Felix, whom I found bending over a cluster of three little eggs, with a caliper in one hand and a clipboard in the other.
“Believe it or not,” he told me, “the reason is that plovers have to perform a little ritual for choosing a nesting site, and it can only be done on soft sand or mud, in a flat, open spot. Here the male uses his feet to dig three slight depressions.
“The female then inspects each spot for quality, chooses whichever she considers the best and then drops little pebbles — or pieces of colored glass, if she can find them — all around the winning depression, and that is where she lays her eggs, whether or not we think it’s logical.”
Felix went on to tell me that female plovers aren’t really all that dumb. It seems, in fact, that they are rather promiscuous and might have three different “husbands,” all of whom may end up sitting on the eggs and caring for the chicks, while their communal “wife” goes off to do something else.
After measuring and numbering each egg, Felix placed it in a small bowl full of water. “If it falls to bottom,” he explained, “it means it was recently laid, whereas if it floats high in the water, it will hatch very soon. In the latter case, if you put the egg to your ear, you may hear the chick inside already pecking at the shell.”
Snowy plover eggs need about 25 days to hatch, and for all that time are threatened by myriad dangers. Although plovers are pretty feisty and will pull on the tail feathers of an enemy bird, there’s not much they can do if a big animal comes along, except to run away from the nest and hope the intruder will follow them.
Plovers tend to run or even fly from the nest when feeling threatened or disturbed and use imaginative distraction displays, especially when approached by mammalian predators.
The chicks, fortunately, pop out of the egg ready to deal with the less than desirable situation their parents have put them in. “Within minutes after hatching,” Felix said, “a baby plover — which is born covered in down — is capable of running far away at high speed.”A newly-hatched plover takes off running at speed. Said Felix
All the people working to understand and protect the snowy plovers of Lake Atotonilco are volunteers who spend many of their weekends at this task. They call their organization Eco Kaban and they receive some financial assistance from Terra Peninsular and Tracy Aviary. They also collaborate with the Max Planck Institute of Ornithology in Seewiesen, Germany, to collect blood samples to determine genetic populations in the Americas.
So just what is the weekend like for an Eco Kaban volunteer?
“They have a bird blind,” Canadian geologist and birder Chris Lloyd told me after visiting the lagoon a few days ago. “It’s a real Mexican-style bird blind: a converted taco stand, the portable kind with wheels, and it’s covered completely with cloth, right down to the ground. So they wheel it in place and check out the area through a spotting scope. They watch the birds flying around and if they keep coming back to the same spot, they say: ‘There’s got to be a nest there.’ So they line up that spot with something off in the distance and go stick a little flag next to it, so they can find it again.
“Next they put a kind of chicken-wire lobster trap over the nest. When the adult plover tries to get to its eggs, it follows a sort of funnel down to the end, goes through and then can’t find its way out. That’s when Said rushes over to grab it before it escapes.
“He brings the bird back inside the blind, which houses a little lab, measures the bird’s wing span, takes a blood sample and bands it. A Mexican colleague studying at the Max Planck Institute will later take all the blood samples to Germany for genetic analysis and eventually there will be a paper on the differences between plover populations on the coast and inland.”
The bird bands are very important:
“For the last three years we have been putting four brightly colored rings or bands on each bird,” Said Felix told me. “These can easily be seen with binoculars, and the color combination identifies the bird as one nesting on Lake Atotonilco.
“This has been a great help for understanding the migratory habits of these birds which disappear every year in October only to pop back up in February. And now we have an even bigger help thanks to the German Research Foundation and the University of California, which has given us several tiny transmitters.
“Very recently our colleagues in Sinaloa were able to put one of these on a plover and it showed us the bird’s movement from the coast of Sinaloa to sites as far as 200 kilometers away, over a period of five months. As a result of all this, we are just beginning to see the migration route of the snowy plovers, so we can help protect them in the winter.”
Eco Kaban is a Guadalajara-based NGO of biologists and ecologists working to preserve the environment “for this generation and for future generations.” In addition to studying snowy plovers at the Atotonilco Lagoon, Eco Kaban helps organize the Christmas Bird Count in the Guadalajara area. This Audubon Society event has been ongoing for 115 years and counts 65 million birds each year.
Eco Kaban’s third project involves tagging birds in Guadalajara’s Huentitán Canyon in cooperation with MoSI, the bird-banding program of the Institute for Bird Populations, a nonprofit corporation founded in the United States in 1989 to study the causes of bird population declines.
The writer has lived near Guadalajara, Jalisco, for more than 30 years and is the author of A Guide to West Mexico’s Guachimontones and Surrounding Area and co-author of Outdoors in Western Mexico. More of his writing can be found on his website.