Seasonal predation by migratory shorebirds recorded in shells of lingulid brachiopods from Baja California, Mexico

Repair scars attributed to shorebirds are very frequent in intertidal popul ations of Glottidia palmeri (Lingulidae, Brachiopoda) from the Gulf of Cali fornia. The multimodal distribution of the scars along the anterior-posteri or axis of the brachiopod shells suggests the existence of strong temporal variation in the intensity of predation. Bootstrap analyses of the scar dis tributions, size-frequency population data, and growth ring data all indica te that the scars are seasonal and originated in the late fall and/or winte r months. The scars record predation by migratory shorebirds that have wint ering grounds in Baja California. The anterior-posterior distributions of s cars can offer insights into seasonal variation in predation on marine bent hos. Also, because seasonal repair scars represent a periodic signal, they may estimate the longevity and growth rates in prey and offer a "sclerochro nological clock" analogous to oxygen isotopes or growth rings. The approach proposed here may be applicable also to the fossil record of some shelly o rganisms.