A Tale of Two Grebes

Clark’s Grebe (left) and Western Grebe in care at Bird Rescue’s San Francisco Bay-Delta wildlife center. Photo by Cheryl Reynolds – International Bird Rescue

International Bird Rescue cares for numerous grebes each year and many of those patients are Western Grebes and Clark’s Grebes. Western Grebes were the bird species most affected by recent California storms in mid-January, which brought dozens of oiled waterbirds into care. We’ve shared many interesting facts about these birds over the years – from how we care for their chicks to their unique feet and leg structure. But did you know that these two grebes can also hybridize?

Both the Western and Clark’s Grebes were described in 1858 by George N. Lawrence. He considered them two separate species, but they were soon condensed into one species – the Western Grebe, with the former Clark’s Grebe considered a “light morph.” You can see in the photos below why ornithologists at the time might have come to that conclusion:

Western (left) and Clark’s (right) Grebes. Photos by Katrina Plummer and Cheryl Reynolds

100 years later, new research led to these grebes once again getting split into two species. Scientists had found that the grebes were very particular when it comes to mating – the two species differentiate from one another by the sound of their voices. However, a small portion of the time, Western and Clark’s Grebes do interbreed. Recent research* suggests that this is more likely to happen as the pool of available birds gets smaller as the breeding season progresses – grebes become less choosy when they have fewer possible mates to pick from.

This grebe in care appears to have both Western and Clark’s Grebe characteristics. Photo by Angie Trumbo – International Bird Rescue

We sometimes see these hybrid birds in care as well – right is a photo of a suspected hybrid patient. You can see how it has some of the traits of both Clark’s and Western Grebes.

When birds like this hybridize, it can raise questions about what their evolutionary future will be. Will they remain two separate species? Will one species genetically overpower the other? Will hybrid birds be able to survive better in our changing world than their purebred counterparts?

Whatever their future may hold, it is important that we protect these beautiful waterbirds and their habitats so that they can continue their evolutionary journey without too much negative impact from humans.

How can you help Western and Clark’s Grebes?

  • Learn to recognize when they are in distress. Grebes do not typically come to shore, so if you see one lying on the ground – call your local wildlife rehabilitator.
  • Keep wetland habitats clean! Attend a local beach or pond cleanup to keep habitats safe for grebes and other wildlife.
  • Clean up discarded fishing gear. Lines and hooks can entangle and injure birds and other wildlife when they are left out in nature.
  • Share what you know. Teach your friends, family, and neighbors about how amazing grebes are and inspire them to take action to protect them too!

*Nuechterlein, G. L., & Buitron, D. (1998, May-Jun). Interspecific mate choice by late-courting male western grebes. Behavioral Ecology, 9(3), 313-321. 10.1093/beheco/9.3.313