Traveling Light

Written by Pam Garrettson
Thursday, May 07, 2015

Pam Garrettson.Tony and I have finished all the air-ground segments in South Dakota, but tonight find ourselves back at our starting point, the capital city of Pierre, SD (pronounce it “Peer” or they’ll know you’re not from around here). Our truck was supposed to be fixed by today, but the part still hasn’t arrived. Meanwhile, we’ve been surveying out of various rental vehicles, transferring supplies and equipment from one to another, schlepping up to the northern part of the state and now back. And once again, I have brought too much stuff. Oh sure, I make my lists and try to pare them down, but find myself thinking, “we might need that..” and it’s a big truck, so I toss it in.

The air crew doesn’t have that luxury (see photo), and neither do the birds we are surveying. Flight is very metabolically costly, requiring 4-10 times the energy as a bird at rest. So birds have all sorts of adaptations for flight, many for saving weight. Some of their bones are hollow, others fused, and birds altogether lack some bones that other vertebrates have. Their reproductive organs (testes, or ovaries and oviduct) regress and are tiny outside the breeding season. Most flighted species only have only one functional ovary. Birds have no urinary bladders, and the one-stop shopping structure known as the cloaca (Latin for “sewer”) serves as both anus and urogenital opening. In bird droppings the green part is the feces, and the white part consists of urates from the kidneys— that’s what ruins the paint on your car, in case you were wondering.

The breeding season is demanding, especially for females, who need extra protein, fat and minerals for egg-laying. Arctic-nesting geese bring all these nutrients with them, and unlike me, they really need everything they bring. When they arrive, their nesting grounds are barren, and until things green up, they rely solely on their stored reserves. They can’t nest until the snow and ice melts, and the longer the delay between their arrival and the start of nesting, the smaller are the clutches they produce. Temperate-nesting waterfowl can procure most of their nutrients on the breeding grounds. Water—the territorial ponds birds loaf on during laying and early incubation, and the larger wetlands that will be used for brood rearing—is what largely determines their productivity. If it’s wet, they’ll nest, and often renest if they lose the first. If it’s dry, they aren’t so persistent, and some forego breeding altogether.

It has been dry in the western Dakotas, and this is an arid area to begin with. This week, the drought here was rated moderate-to-severe. We surveyed this morning near Bison, SD, in a steady rain, and while it felt like a lot of water while it was dripping down our necks, most of it will probably soak quickly into the very dry ground. However, where there is water, we’ve observed decent numbers of shovelers, gadwall and blue-winged teal, plus a smattering of the earlier-nesting mallards and pintails. More rain is forecast for the weekend, and we’ll see if that helps out the later nesters.

The air crew travels light, the ground crew, not so much.

The air crew travels light, the ground crew, not so much. Photo by Pam Garrettson, US FWS