Avian collisions with human-made objects are relatively common; however, documented avian collisions with naturally occurring objects are rare in scientific literature. On 22 April 2002, we observed a tree swallow (Tachycineta bicolor) entangled in the spines of a teddy bear cholla (Opuntia bigelovii) in the Tule Mountains, Cabeza Prieta National Wildlife Refuge, Arizona. Two possible causes of this incident include the swallow flying into the teddy bear cholla, possibly being blown by a gust of wind, or being placed there by a loggerhead shrike (Lanius ludovicanus). Because of the flying abilities of swallows and documented diets of loggerhead shrikes, either would be unusual.