Chapter 3: Comparative Reproductive Ecology of the Auks (Family Alcidae) with Emphasis on the Marbled Murrelet

Abstract

Marbled Murrelets (Brachyramphus marmoratus) are comparable to most alcids with respect to many features of their reproductive ecology. Most of the 22 species of alcids are colonial in their nesting habits, most exhibit breeding site, nest site, and mate fidelity, over half lay one egg clutches, and all share duties of incubation and chick rearing with their mates. Most alcids nest on rocky substrates, in earthen burrows, or in holes in sand, around logs, or roots. Marbled Murrelets are unique in choice of nesting habitat. In the northern part of their range, they nest on rocky substrate; elsewhere, they nest in the upper canopy of coastal coniferous forest trees, sometimes in what appear to be loose aggregations. Marbled Murrelet young are semi-precocial as are most alcids, yet they hatch from relatively large eggs (relative to adult body size) which are nearly as large as those of the precocial murrelets. They also share with precocial murrelets an early age of thermoregulation, as indicated by a short brooding period. Hatching success in monitored Marbled Murrelets nests was somewhat lower and fledging success was markedly lower than for other alcids. The lower rate of reproduction was attributed in part to egg and chick predation. Marbled Murrelet young raised in forest nests may incur additional mortality on their trips from inland nest sites to the ocean. El Niño effects may also decrease productivity in this species. To document murrelet reproduction more fully, further study of individually marked, breeding Marbled Murrelets and their young conducted during periods without El Niño influences is needed.

Parent Publication

• Ecology and conservation of the Marbled Murrelet

Citation

De Santo, Toni L.; Nelson, S. Kim. 1995. Chapter 3: Comparative Reproductive Ecology of the Auks (Family Alcidae) with Emphasis on the Marbled Murrelet. In: Ralph, C. John; Hunt, George L., Jr.; Raphael, Martin G.; Piatt, John F., Technical Editors. 1995. Ecology and conservation of the Marbled Murrelet. Gen. Tech. Rep. PSW-GTR-152. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; p. 33-48