{"id":1417,"date":"2017-11-17T12:00:41","date_gmt":"2017-11-17T12:00:41","guid":{"rendered":"http:\/\/wordpress.viu.ca\/biol325\/?p=1417"},"modified":"2017-12-04T16:53:07","modified_gmt":"2017-12-04T16:53:07","slug":"i-believe-i-can-fly-underwater","status":"publish","type":"post","link":"https:\/\/wordpress.viu.ca\/biol325\/2017\/11\/17\/i-believe-i-can-fly-underwater\/","title":{"rendered":"I Believe I Can Fly (Underwater)!"},"content":{"rendered":"

Common Murres (Uria aalge<\/em>) are recognizable by their black and white, penguin-like appearance and their hilarious calls. They also have one other distinctive trait that needs to be explored further, their diving abilities!<\/p>\n

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This Common Murre looks ready for takeoff… but is it going to go skyward or underwater? Photo by Alex McDonald, Property of Stubbs Island Whale Watching<\/p><\/div>\n

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Murres diving just under the surface. Photo by Paul Nicklen\/National Geographic Creative<\/p><\/div>\n

When you think of diving birds, your mind goes to penguins. Of all the diving birds, the penguins can reach the deepest depths (Piatt and Nettleship, 1984). Common Murres fill the same ecological niche of penguins in the Northern Hemisphere. They can dive from 170-230 m deep while foraging, exploiting similar prey sources such as fish, squid and marine invertebrates (Piatt and Nettleship, 1984). They both pursue their prey underwater and have numerous adaptations for underwater “flight” and feeding such as increased body size to facilitate deeper dives.<\/p>\n

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A Humpback Whale comes in and scoops up all the fish that the Common Murres and gulls worked so hard to round up into a tasty bait ball. Photo by Alex McDonald, Property of Stubbs Island Whale Watching<\/p><\/div>\n

Common Murres are visual foragers, diving after prey from the surface all the way down to depths your average scuba diver can’t fathom reaching (Cairns et al., 1986). They are often found in multi-species groups, foraging on bait balls. They work in conjunction with other diving birds as well as surface birds like gulls and eagles to corral fish into tight balls, making it easier to catch them. These bait balls also attract other marine predators such as whales, dolphins, seals and sea lions, hoping to catch an easy meal.<\/p>\n

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Success! This Common Murre holds its prize, a cuttlefish. Photo by BSIP\/UIG via Getty Images<\/p><\/div>\n

However, it’s not always about an easy meal. They also take a lot of long, deep dives while foraging, often more than 50 m deep (Hedd et al., 2009). If you’re a scuba diver, you know that it’s not easy to propel yourself down to that depth at any great speed. For the Common Murre though, that’s no problem!<\/p>\n

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The deep dives they perform are costly, often in cold northern waters that can reach sub-zero temperatures. There are two main parameters that need to be considered when studying diving abilities: swimming speed and diving time (in regards to oxygen storage and metabolism) (Croll and Maclaren, 1993). Common Murres can swim at approximately 1.5-2 m\/s and stay under water for almost 3 minutes (Hedd et al., 2009). On average they dive for about 67 seconds (Croll and McLaren, 1993). They have narrow hips and cylindrical bodies to streamline their dives, with their legs functioning as rudders to steer. They have small wings, useful for propelling themselves underwater in a flight-like motion but still functional for flight above water as well. Check out how they “fly” underwater using their wings in this short clip:<\/p>\n