Birds, gas stations, and mud: just an average road trip for semipalmated sandpipers

A discussion on what sandpipers eat, why it’s important, and how climate change is affecting them.

Imagine this: you are on a road trip and are coming up to an exit. You feel your tummy rumble and pull off at the nearest gas station. You may get lucky and find a cornucopia of a gas station with a restaurant and a full buffet, or you may get a gas station that’s fallen on hard times, with only a limited selection of snacks, many of which are past their sell-by dates. Foraging on a journey can be a roll of the dice.

Believe it or not, we have this gamble in common with a famous local bird species, the semipalmated sandpiper. Every fall, thousands of these tennis ball-sized birds travel from the Arctic on their way to South America. But their version of a gas station is the mudflats of the Bay of Fundy. Each year, hundreds of thousands of them migrate through the Bay of Fundy and hundreds of people flock—no pun intended—to see them fuel up along their 4000 km journey. 

What they eat matters when they stop at the mudflats; remember, for them, it is not only road trip food, but also their fuel. Sandpipers are known to eat small invertebrates called Corophium volutator, nicknamed ‘mud shrimp’, as well as polychaetes, essentially furry mud worms, and biofilm—a thin, slimy, microbial goo. If you have ever stepped on a slippery rock when visiting the bay, you have stepped on biofilm! It is a collection of microorganisms that get their energy from the light like plants and, in the Bay of Fundy, live on the surface of the mud.

Luckily for the sandpipers, the mudflats are more of a restaurant buffet rather than a poorly-stocked gas station. “They will almost eat anything[…] they come here to just eat!” said Dr. Diana Hamilton, a professor of biology at Mt. A who studies sandpiper ecology. These birds skim the mudflats with little hairs on their tongue, eating everything from mud shrimp to biofilm, explained Hamilton.

However, what quality of food do they have access to here in Atlantic Canada? As we know, a bag of chips is not as good for you as a vegetable cup. Do sandpipers have a similar choice between low- and high-quality foods? Also, with the growing effects of climate change, will this change what food is available for sandpipers in the future? Will their favourite gas station fall on hard times? 

Research out of Hamilton’s lab, led by Mt. A alumna Jenna Quinn, explored the fatty acid concentration in a variety of sandpiper food items from Fundy mudflats. Fatty acids are important because they provide long-term energy, which is needed for long-distance migrations. Therefore, if the birds don’t get enough fatty acids while they are here, it could affect the likelihood that they will make it to their summer breeding grounds in South America. 

Importantly, the study found that “sandpipers in the Bay of Fundy can meet their [fatty acid] needs with a variety of dietary options,” said Hamilton. In terms of the “availability of fatty acids, the biofilm is as good as the invertebrates [who] are eating the biofilm.” This tells us that the current state of the mudflat makes for a prime stopover location for these birds. 

But what if this state was to change? What if biofilm and other food options for sandpipers became negatively impacted by climate change?

“In order to make appropriate conservation decisions about an organism, you [have to] understand how it interacts with its habitat,” said Hamilton. When it comes to future planning, “migratory birds, in general, are a particular conservation challenge because they have a wintering ground, a breeding ground, and they usually have a staging space in between—which is what we are here,” Hamilton explained. In the past decade, populations of sandpipers have halved, so now more than ever it is important that we begin paying closer attention to how human activity and the associated changes in climate are impacting the important ecosystems along our shorelines.

“After seeing the thousands of sandpipers fly in, I was mesmerized! This is a natural beauty we need to protect,” said Kailey Trenholm, a Mt. A student and local to the area. We don’t want our area to become a gas station that has fallen on hard times, we want it to be a flourishing cornucopia gas station with a restaurant that can fuel sandpipers for their long journey and give the best chance to return in years to come. It will take community effort and public awareness to make this happen.

To learn more, check out ‘Fatty acid composition and concentration of alternative food of Semipalmated Sandpipers (Calidris pusilla) in the upper Bay of Fundy, Canada’ by Quinn et al. (2017).

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