So I was a skinny kid. I was a picky eater and would sometimes skip meals (I kind of wish I had that problem now, I eat everything and have to actively control my portions). It was to the point where my parents thought there was something wrong with me. They always used to use the phrase you eat like a bird. Which I would not know how to take because, lets be honest, how much do birds REALLY eat? Well I was doing some research for a post the other day and came across some numbers that I wanted to share about the whole eating like a bird thing. The results were staggering.
So I was researching to write a short post about the Mourning Dove (go check out the previous post) when I saw on the allaboutbirds.com website how much they ate. The stats showed that a Mourning Dove eats 12%-20% of its body weight and up to 71 calories per day. That took me back to my dad telling me Jay you eat like a bird so I had to do some more research and number crunching. So a dove is a relatively small bird, but by far not the smallest bird species. They weigh in at an average of 4 oz. (113.4 g). So if a Mourning Dove eats 15% of its body weight, it eats .6 oz (17 g) of food per day. Which to a human is like literally a handful of peanuts. That cant be significant right? WRONG!! I did some comparisons. If a human weighing 150 lbs. (68 kg) eats 15% of their body weight in food they eat a staggering 22.5 lbs. (10.2 kg) of food a day (according to a nutrition website I found, humans in America eat on average 3-5 lbs (1.3-2.3 kg) a day). That is a HUGE difference, that means that a human on average eats only around 2.6% of their body weight each day. Now for the calories, these dove eat around 71 calories per day. In the light of counting calories and when a burger is like an insurmountable amount of calories, that isnt that large right? WRONG again!! Lets put that into context with what we are supposed to eat. A healthy amount of calories for the same 150 lb (68 kg) human above is 2000 calories per day. That equals out to around 13.3 cal/lb (29.4 cal/kg) or 0.84 cal/oz (0.029 cal/g). Now we remember that this bird weighs all of 4 oz (113.4 g) and that 71 calories goes a long way. To be exact this 4 oz (113.4 g) dove eats 227.56 cal/lb (628 cal/kg) or 14.2 cal/oz (0.682 cal/g). This is also a substantially higher amount. For both amount of food and calories per body size this is about a 6-7 times larger number for birds than it is for humans. So If you are eating like a bird it is pretty bad and you may want to see a nutritionist because it will most likely lead to obesity. Unless of coarse its Thanksgiving, then that is pretty normal, and ironically you will probably be eating a bird.
Upon a little more research I found that these stats for the Mourning Dove is pretty low compared to some other bird species. Chickadees eat around 35% of their body weight in food per day and hummingbirds can eat somewhere upwards of 100% their body weight in nectar per day. Just dont go around telling people they eat like a bird anymore because if they have seen this post, in which they will probably take offense.
I did want to briefly (to the best of my ability) give my best explanation to why this is (and how I know). I had a grad school professor that taught me Comparative Anatomy and Physiology. He hit home a lot about the subject of Ficks Law (Im not going to go into great detail, google it for better understanding). Ficks Law is a measure of diffusion, or exchange rate between 2 areas through a concentration gradient. In this scenario we are talking about heat loss through skin. Ficks Law explains that when you have a higher surface area:volume ratio you loose heat faster (because you have more surface area touching the outside world for the heat to escape through). Smaller organisms such as birds have a very high surface area:volume ratio, so they loose heat a lot faster than larger animals, ie. humans. Because birds and mammals are both homeothermic or warm-blooded they are required to keep their body temperatures at a high level. Since these birds loose heat faster, and because flying takes up a lot more energy than land locomotion, their metabolism is constantly running at a increased level to keep their bodies the correct temperature. To do so they need constant fuel to keep that engine running.
This is especially important during the winter months when food is scarce and temperatures are lower. Putting out birdseed is important during these months to help these birds get through the winter. With them loosing vital habitat due to development, they loose the areas that were once rich in food. Feeding these birds is one way I like to think I am helping out. And, to tell the truth, I think they are awesome to look at as well.
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I did want to provide as brief an explanation as possible for why this is the case, as well as how I know. A professor in graduate school taught me Comparative Anatomy and Physiology. He made a lot of points regarding Fick’s Law (I won’t go into too much detail; for a better understanding, google it). Diffusion, or the rate of exchange between two areas through a concentration gradient, is measured by Fick’s Law. Here, we are discussing heat loss through the skin. According to Fick’s Law, heat escapes more quickly from objects with higher surface area to volume ratios because there is more surface area in contact with the external environment. Due to their higher surface area to volume ratio, smaller organismslike birdslose heat much more quickly than larger animals. humans. Birds and mammals need to maintain high body temperatures because they are both homeothermic, or “warm-blooded.” Because flying requires a lot more energy than land movement and because these birds lose heat more quickly, their metabolism is continuously elevated to maintain the proper body temperature. To do this, they require fuel to keep the engine running continuously.
After doing some additional research, I discovered that these Mourning Dove statistics are rather low when compared to those of some other bird species. Hummingbirds can eat anywhere from 10% to 20% of their body weight in nectar each day, while chickadees consume about 335 percent of their body weight in food each day. Just remember not to tell people anymore that they “eat like a bird” because they will likely take offense if they have seen this post.
This is particularly crucial in the winter when food is scarce and the temperature drops. In order to help these birds survive the winter, it is crucial to put out birdseed during these months. They lose the areas that were formerly rich in food because they are losing essential habitat as a result of development. I like to think of feeding these birds as my way of contributing. Furthermore, I think they are really amazing to look at.
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So I was researching to write a short post about the Mourning Dove (go check out the previous post) when I saw on the allaboutbirds.com website how much they ate. The stats showed that a Mourning Dove eats 12%-20% of its body weight and up to 71 calories per day. That took me back to my dad telling me Jay you eat like a bird so I had to do some more research and number crunching. So a dove is a relatively small bird, but by far not the smallest bird species. They weigh in at an average of 4 oz. (113.4 g). So if a Mourning Dove eats 15% of its body weight, it eats .6 oz (17 g) of food per day. Which to a human is like literally a handful of peanuts. That cant be significant right? WRONG!! I did some comparisons. If a human weighing 150 lbs. (68 kg) eats 15% of their body weight in food they eat a staggering 22.5 lbs. (10.2 kg) of food a day (according to a nutrition website I found, humans in America eat on average 3-5 lbs (1.3-2.3 kg) a day). That is a HUGE difference, that means that a human on average eats only around 2.6% of their body weight each day. Now for the calories, these dove eat around 71 calories per day. In the light of counting calories and when a burger is like an insurmountable amount of calories, that isnt that large right? WRONG again!! Lets put that into context with what we are supposed to eat. A healthy amount of calories for the same 150 lb (68 kg) human above is 2000 calories per day. That equals out to around 13.3 cal/lb (29.4 cal/kg) or 0.84 cal/oz (0.029 cal/g). Now we remember that this bird weighs all of 4 oz (113.4 g) and that 71 calories goes a long way. To be exact this 4 oz (113.4 g) dove eats 227.56 cal/lb (628 cal/kg) or 14.2 cal/oz (0.682 cal/g). This is also a substantially higher amount. For both amount of food and calories per body size this is about a 6-7 times larger number for birds than it is for humans. So If you are eating like a bird it is pretty bad and you may want to see a nutritionist because it will most likely lead to obesity. Unless of coarse its Thanksgiving, then that is pretty normal, and ironically you will probably be eating a bird.
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