Dear Bird Folks,

Just before last week’s storm arrived my feeders were packed with birds. I have a theory that birds know when a storm is coming and thus will eat more. Is that correct? Whatever you say I’m okay with.

– Tony, Chatham, MA

I like you, Tony,

I’m glad you are willing to accept my answer. Sometimes people ask me a question and if I don’t provide the exact answer they are looking for, they argue with me. It’s like they are trying to pick a fight, but they should know I’m always Mr. Agreeable. Here’s an example: Today a guy asked, “What is the best kind of birdseed to use?” I answered, like I always do, “Sunflower seed.” He then replied, “My brother uses a special mixed seed that he swears works better.” Now what do I do? Call the guy’s brother an idiot? No matter what I say to this guy, he’s going to respond, “But my brother says…” It’s a no-win. That’s why I’m glad you are going to be okay with what I say. (Oh, in case you were wondering, I did call that guy’s brother an idiot. I was kidding about being Mr. Agreeable.)

Because I like you, Tony, I’ve decided to agree with your theory about birds eating before storms. Also, I agree with you because you are right. Birds do, in fact, eat more when a storm is coming. Unlike humans, who only eat extra food when there’s a party, or on the weekend, or during the week, birds’ feeding habits are based on need. Pre-migration is one time when birds will pack on the extra pounds. Pre-bad weather is another. For years researchers (and you) have casually observed birds eating extra food before storms arrive. But they couldn’t really prove if this was a fact or merely a coincidence. So, researchers at Western University went out and built something called a “hypobaric climatic wind tunnel.” (I don’t know why they didn’t just ask to borrow mine, but whatever.) Here’s what they found out.

By controlling temperature and the amount of light, scientists were able to duplicate winter conditions for the birds lucky enough to be shoved inside the hypobaric climatic wind tunnel. Under normal conditions the birds would wake up each morning, preen a bit, stretch a little and maybe check to see how their stocks performed in the overnight markets before heading out for breakfast. But when scientists lowered the air pressure inside the tunnel, the birds would skip their usual morning routine and immediately start searching for food. Low pressure means storms, and storms could force birds to hunker down for hours or even days, so they get out and stock up while the getting is good. You know, like we hysterically rush out for milk and bread the second we see a single snowflake. It’s the same thing.

The next question has to be: How do birds know when bad weather is coming? Do they have a sixth sense, an innate ability to foresee storms or perhaps The Weather Channel app on their iPhones? Birds have hollow bones, and when I was a kid I was told that they could feel air pressure changes in these bones, much like old people can feel bad weather in their joints. Well, the hollow bone theory turned out to be as accurate as the experts who predicted that the 2013 World Series champion Boston Red Sox (Sweet!) would finish in last place. Oh, sure, birds have hollow bones, but they don’t use them to forecast the weather. Instead, they use their ears. It appears birds have pressure sensitive organs in their ears. I guess that shouldn’t come as a surprise; our ears are also pressure sensitive. That’s why our ears pop in elevators. Ear pressure is also why babies on airplanes do all that screaming (particularly the ones sitting next to me). Only with birds, this sensitivity is far more acute and far more important.

Air pressure change not only tells birds when to eat extra food, but it also provides them with critical migration information. To save energy, birds migrate along frontal boundaries. Like eastbound planes getting pushed along by the jet stream, birds get a boost from the winds associated with moving weather fronts, especially high-pressure fronts. But when birds detect low pressure, which is frequently associated with a coming storm, they will often settle down and wait for it to pass. Birders study these weather patterns because it helps them to know when and where migrating birds will be. (Well, most birders know where the birds will be. I always seem to get it wrong and just end up getting caught in the rain.)

Birds also use their pressure detecting skills in flight. During migration many birds travel at night. Their pressure sensitivity helps them maintain the proper cruising altitude, which allows birds to avoid natural obstacles. But most importantly, flying at the proper cruising altitude allows the birds to safely use their FAA-approved electronic devices, which they love.

You aren’t alone in your interest in birds’ ability to predict storms. Scientists are continuing to work on this subject. In a recent discovery, they found the same sensitive organs that birds’ have in their ears are also in the bodies of sharks (yes, sharks), apparently to help them detect changes in water pressure. (Who knew birds and sharks had something in common?) So, if you look out your window, Tony, and find tons of birds chowing down on your feeders, you can assume a storm is coming and you’d better head out for bread and milk. But if you look out and see sharks eating from your feeders, forget the bread and milk and head to the optometrist.