Ruff sex is hereditary


From one of the world’s largest ruff aviaries perched atop Burnaby mountain, SFU researcher David Lank has come across a crucial discovery that genetics — not environmental factors — drive courtship and mating practices in these unique birds.

Lank, an SFU research associate and adjunct professor of biological sciences, has spent three decades studying the unique mating patterns of the male ruff bird, a type of sandpiper originally from Finland. These birds, bred by Lank in the aviaries at SFU, are the only known ruffs in North America. 

Lank was originally drawn to these birds because of the mating patterns specific to their species. The males are unique in that they belong to one of three distinct groups, each with their own behavioural patterns in regards to mating. However, unlike most animals, these differences in mating are not a result of their environment, nor a result of different stages of development. Instead, they are a result of genetic variants in the three types of the male ruff birds. 

The three types of ruff birds are the territorial, the wingman, and the female mimics. The territorial make up 85 per cent of the population, acting as most birds do when trying to mate; they display their plumage to attract the females, and hope to mate with those that approach their selected territory. 

The wingmen function as their namesake states. They join one of the territorial males, forming a competitive yet helpful alliance to attract the females. However, once a female ruff approaches, the alliance transforms into a rivalry of who can mate with the female first.

Lastly, the female mimics are similar to female ruffs in appearance. They are smaller than the other males, and only form one per cent of the populous. Unable to attract females themselves, they lie in wait by the other males, and try to jump on an approaching female. 

This discovery made about the ruff birds is important because, according to Lank, “major differences in personality [are] attributable to a gene.” In other words, behavioural patterns can be determined before these birds are even born. 

He explained to SFU News, “Ruffs lack developmental plasticity, which means they do not change their mating behavior with social circumstances, or learn from experience.” This has proven very informative to researchers as it proves that behaviour is not always a learned trait, and it is now scientifically proven to be something these ruff birds inherit.