Dear Bird Folks,I happened upon your website and was fascinated by your astute writing. Perhaps you can help with this. My husband has been commenting on the "fat, pregnant robins" around our house. He thinks the lean, svelte robins are the males. I think he's wrong, but I can't give him a good explanation as to why the fat robins aren't pregnant. Can you help? - Mindy, Colorado
You bet, Mindy,I'm more than willing to help you, especially after you said such nice things about me. Even though lots of people have said my writing is "astute" (and by "lots," I mean you are the first one), I want to help because I feel bad for you. Not only did your marriage with Mork not work out, but also because you ended up with a guy who thinks all fat robins are pregnant. If fat always equals pregnant, 80% of the men out there would be expecting twins. Have you seen some of those men? This morning I waited on one guy who looked like he could have had several people inside of him, kind of like the Octo-mom, only with a beard. Birds come in all shapes and sizes. Some are tall and slender like stilts, while others have elegantly tapered bodies like swallows and terns. Owls are typically robust; sparrows are mostly compact. Then there is the pelican, whose body-type defies description, as if it was created with spare parts. The American Robin, like many Americans, has opted for the round look. Robins have rather plump bodies that some observers describe as "chesty," which might explain their popularity. Robins are thrushes but unlike the spotted thrushes (Wood Thrush, Hermit Thrush, etc.), in which both sexes look the same, robins are sexually dimorphic. While sexual dimorphism may sound like something kinky, it only means that the male and female birds are readily distinguishable. Boring! The fact that Mr. and Mrs. Robin each has a different look may not be exciting to read about, but it does mean that your husband should be able to tell which is which and doesn't have to think the fat ones are pregnant females. Female robins have gray backs and heads and washed-out orange breasts. The male has a deep orange breast and a black head. And here is the interesting part, if any of this can be called interesting: Male robins are typically the larger bird. So if any robin is going to look pregnant, it will be the male. However, all of this is silly because birds don't become pregnant, no matter how much they've had to drink. Pregnancy is a mammal thing. Birds, which need to stay light in order to fly, can't be weighed down with things growing inside of them. That's why they lay eggs. Mammals have another odd thing that birds would rather not get into...nursing their young. I can't imagine a bird would be very good at swooping through the air while carrying pouches filled with warm milk. A heavy load of milk is probably the main reason why cows don't fly. Some people might ask: "What about the cow that jumped over the moon?" To which I would reply: "Ah, hello? Jumping is not flying." The better question would have to do with bats. Bats are mammals, yet female bats are able to fly around with tiny batlets growing inside of them. They also nurse their babies. How can bats pull it off when birds can't? I don't really know because I'm not a batman, but I do know that bats typically only have one baby at a time while birds may produce four, six or even sixteen offspring at once. Also, there are far more birds in the world than there are bats, so the birds' egg system appears to be the better option. While I'm sure the robin's body shape has a lot to do with its preggo-look, it doesn't explain the other part of your hubby's observation, that the "lean, svelte" robins are the males. A "svelte" robin? I don't think so. That's like a svelte plumber. They don't exist. I have no idea what birds he is looking at and I can't travel to Colorado to find out because Joe Biden says I have to stay home or the swine flu will get me. However, I do have a theory. Male robins have longer tails and wings than the females do. It's possible that their longer profile makes the male birds look thinner than the females. It's a weak theory, but that's all I have. On another topic: It is now the first week of May. That means for anyone who wishes to do so, it's time to put out your hummingbird feeder. The other thing May means is that my phone will be ringing nonstop with people asking about the formula for hummingbird nectar. Here it is, so you won't have to call: one part sugar to four parts water. I repeat: one part sugar to four parts water. Red food coloring is not needed although some folks boil the water to help dissolve the sugar and to boil off any additives in the water (like chlorine, fluoride, etc.). It's also important to clean your feeders and change the sugar water every few days. If you don't do it, your birds could become sick and Joe Biden might not let them migrate come fall.