Sinaloa, the Mexican state that lies along Sonora’s southern border, is well known for the popular beach-front tourist destination, Mazatlán. You might also associate it with a major drug cartel, but if you’re a birder you’ll probably think first of its namesake bird, the beautiful Sinaloa Wren, Thryophilus Sinaloa. The Sinaloa Wren is endemic to western Mexico, and just 21 years ago was unknown north of Alamos, deep in southern Sonora. However, by 2006 it had expanded its range into central and northern Sonora, and ultimately made its first appearance in Arizona in August, 2008, in Patagonia. Today, 12 years later, Sinaloa Wrens continue to appear in Arizona rarely but expectedly, and although they have not been seen in Patagonia for 6 years, for the past 3 years single birds have been found in both the Tubac area and in Ft. Huachuca. Sinaloa Wrens have not yet been found in any other U.S. state, nor has more than a single bird been found, so it’s still a crowd-drawing event when one is reported here.
This may well change, however, since the wren now is routinely found nesting at Rancho El Aribabi on the Cocospera River just 35 miles south of the Arizona border. We visited El Aribabi in May, 2014, and although we never saw a Sinaloa Wren, we clearly heard one singing, a loud but harmonious song that competed well with the clatter of Yellow-breasted Chats. We returned to El Aribabi again this May, and this time found two pairs of Sinaloa Wrens building purse-like grass nests draped across riparian tree branches. Each monogamous pair sallied out to find grass and fine twigs, added them to the growing nest and, as they flew away, broke into song.
We videotaped two minutes of this nest-building and singing activity, which can be found on YouTube here. This song is well-described as ‘complicated and harmonic.’
This beautiful bird has moved 400 miles north of Sinaloa in just 2 decades, and is now nesting 35 miles south of Arizona. I think it’s safe to bet it won’t be long before she loses her endemic status in Mexico. After all, birds can’t read and they have wings.