On July 5 we had a very unusual flycatcher, most likely a Myiarchus, along the Rio Grande Bosque in Albuquerque NM. The Ash-throated Flycatcher is the only Myiarchus expected here. It is a common breeder, and we are very familiar with it. This mystery bird did not have any yellow on the belly, or any rufous on the wings or tail, and there were no obvious wing-bars. The bird sat on a wire for a few minutes, slightly lifted its tail up a few times, and preened. Then it flew off. The bird was about 100 feet away, but in good light. No vocalizations were heard, but it was far enough away that we could have missed them. Overall color is gray, with lighter gray on the breast than on the back. There is a light gray collar and throat. We went through all of our books, including Mexican Field Guides, and nothing seem to match. Most probable ID is some sort of very worn Ash-throated, but the thought of something more interesting is tantalizing. The only other flycatchers normally found here in July are Black and Say's Phoebe, and Western Wood-Pewee. It certainly is not any of these.