When the Food Comes to You

Long-distance migration of prey synchronizes demographic rates of top predators across broad spatial scales (2016) Ward et al, Ecosphere, DOI: https://doi.org/10.1002/ecs2.1276

Disconnected Orca populations often use the same food source. So can this lead to similar demographic rates? (Image Credit: publicdomainpictures.net, CC0 Public Domain)

The Crux

Populations that experience some kind of connection are classified as “meta-populations”, as they are all interconnected in some way and can influence one another. Although these populations may be geographically and reproductively isolated, meaning that they are in different places and the organisms from the different populations don’t breed with one another, certain environmental factors may cause these populations to grow or shrink in similar ways.

The key to understanding how this synchrony between the varying populations happens is understanding what connects them. Killer whale (orca) populations in the northeast Pacific Ocean inhabit three distinct areas, with orcas from the northern and southern populations never coming into contact with one another. They do, however, feed on the same salmon populations that migrate from where the southern population lives to the where the northern lives. The authors wanted to find out if this connection via a food source could result in the demographic rates of these distant populations syncing up.