This order comprises four families:

• Procellariidae (petrels, shearwaters)
• Hydrobatidae (northern storm petrels)
• Oceanitidae (southern storm petrels)
• Diomedeidae (albatrosses)

References

Ferrer-Obiol J, James HF, Chesser RT, Bretagnolle V, Gonzalez-Solis J, Rozas J, Riutort M, and Welch AJ (2021), Integrating sequence capture and restriction site-associated DNA sequencing to resolve recent radiations of pelagic seabirds, Sys. Biol. syaa101. (pdf)