We call them “Trash Birds” but not because they’re bad, but rather, it’s a little personal joke about their habitat – they love garbage, and the two places where we can always find them when counting birds in Mexico is the dump in Empalme and the garbage pile behind the Guaymas Protein Company fish canning plant at the end of Sanchez Taboada. While normally associated with big mammals like water buffalo and dairy cows, the birds in Mexico find an easier meal tearing through plastic bags.
Cattle Egrets (Bubulcus ibis) are a very adaptive bird. Native to Spain, Portugal, and Western Africa, their worldwide expansion is an incredible success story. In the New World, they were first seen in British Guiana in 1877. From there, they slowly colonized the coasts of the southern Caribbean over the next 50 years and finally appeared in Florida in 1941 before breeding there in 1953. By 1956 they were being reliably seen along the entire US eastern seaboard. The first western bird was collected in San Diego in 1964. While busy colonizing the US, they were also spreading through Central America and Europe, reaching Ireland and Iceland in 2008. On the other side of the world, they colonized New Zealand and Australia in the 1960s. Their populations have risen and fallen with the changing patterns of land use around the world, for example, the shrinking of the farming industry in New England curtailed their growth in that region while adapting to living alongside range cattle allowed them to expand in the western US. And of course, there are always landfills.
How they got to these places is unknown, but none of the populations show any sign of having escaped from captivity. The birds in the western hemisphere are assumed to have flown from Africa to Brazil in the mid to late 19th century.
Here in central New Mexico, they’re a migrant, appearing in the spring and disappearing when it gets frosty. When I first moved here 30 years ago, seeing one required getting in the car and driving 110 miles south to Bosque del Apache; I recorded my first sighting there in April of 1991. Now, in season, they’re a neighborhood bird. Over the past 20 years, I’ve seen them closer to home much more frequently, mostly in the flooded fields in the North Valley. I still vividly recall the day they became a “yard bird,” June 20th, 2009. Sitting in the driveway, home on a trip from China, throwing the ball for Teddy. Overhead, 10 birds flying off to the south.
A couple of days ago, these three showed up in a flooded pasture just down the road. Walking in the tall grass, skewering some kind of big bug for an afternoon meal. While there isn’t a water buffalo within a thousand miles – irrigation alone attracts them to an easy repast of floating bugs and mammals. Far easier than picking a tick off the back of a moving bovine. When the flood sinks in, they’re off to the next field.
A little bit of sub-Saharan Africa, right here in the central Rio Grande Valley.