Of all animals, birds can be especially baffling (other than Homo sapiens). Although each bird species has typical behavior, they sometimes will ‘change their minds’ on how they look. And even where they will be. Nor do they send out memos informing avid avian paparazzi. You know, the ones with multiple field books in their hands, spotting scopes slung over their shoulders, and the gigantic camera lenses that almost require their own wheelchair. I don’t fault passionate birders at all. I’m one, too (albeit not an expert). The bird portraits that adorn photographers’ websites are all very nice, too.
Perhaps my years in field biology explain my preferences for watching and learning about animal behavior (including birds) rather than obsessing on finding the perfect bird in its guidebook color and within the human-made boundaries of habitat. Why else would one of my favorite personal photos be one of a Canada goose blowing bubbles in the water?
“Well, the ______ (fill in the blank with bird name) were NOT at the _____ (fill in a specific location on the Refuge) on/at _____ (fill in with time/date reference). We didn’t see them! Are they not here? Where are they?”
We volunteers are often asked about where the birds are when they are not in their expected place at the expected time. We often respond with “They didn’t send us a memo on where they were going!” or “Birds have wings and they fly wherever they want, whenever they want.” I’ll often resort to “You know when they say about people, ‘Follow the money’? With birds, it’s ‘Follow the food.”
Well, it’s true!
Birds are fortunate that they can migrate over thousands of miles from one territory to another. Plants and most other animals do not. Most birds nest and brood in a specific habitat, one that provides the food they need to lay eggs and fledge their young. The right habitat must also provide cover and protection from predators. As the young birds grow, they are taught to fly and hunt for food. They also learn how to socialize outside of their family units. As the seasons change, they are encouraged to exercise and train for long daily flights, just like an athlete trains for a marathon. By the time they are ready to migrate elsewhere, they are almost adults.
Migration still perplexes biologists in many respects. What are the signals informing them when to leave one area and go to another? Do they always return to the same place they were born (called natal philopatry)? Do they always migrate to the same wintering location? What determines their migratory route? Do they ever veer away from their traditional route? We’re still investigating these questions. And often times, the answers raise more questions.
Some bird species demonstrate very strong natal philopatry. Sandhill cranes are one of these species. I have known some humans who have demonstrated this, too. 😉 Other bird species are not as tied to their birth place and may choose other nesting locations far from their original place. Likewise, not all birds exactly follow a map with planned stops on their migrations. Only humans do that.
Some of the factors that influence their seasonal locations (nesting and overwintering) are those that also influence humans. Weather, temperature, food availability, water sources, cover for protection, and even topography. High mountain ranges are a barrier to many migrating birds. Although larger birds can often migrate at high altitudes and fly over occasional obstructions, bad weather is often associated with long ranges of high mountains. Birds have learned through their evolutionary history what to avoid to conserve energy. They have also learned from their parents, and those before them, where food and water sources are during their long migrations. Thus, most of the continental flyways can be traced like a hopscotch board from one habitat to another where food and water are readily available for large flocks of migrating bird species.
They follow the food and water!
Of course, there are exceptions to everything. Life is not black and white, but mostly a large expanse of gray area in between. Many scientists have documented that some birds are changing their traditional migratory routes, nesting grounds, and/or their wintering locations. Two major factors impacting these are loss of habitat and climate change.
Here we go back to the same source: food and water. As temperatures change, plants are becoming rare in one location, but might be increasing in population in another location. For example, some trees and other plants that grew near the base of mountains are now becoming less available or even rare. However, some of these same species are thriving higher up on mountainsides, where they were at one time rarely seen.
Likewise, many birds that nested in some of those plants, or were sustained by the plant seeds or other plant parts, are following the plants further up the mountain. The same applies on larger scales of land: some birds are being seen and documented in areas they were never, or rarely, seen before because their water and food sources have changed.
Additionally, some of their historic and preferred habitats have disappeared due to urban expansion. While some birds can adapt to mutually living with humans in their metropolitan areas, others cannot. With urbanization comes destruction of wildlife habitat. Their food source may no longer be adequate, or there is less available for them to nest and raise their young. Even loss of natural cover from predators may severely reduce bird populations.
Their only memo to us humans is “We’ve gone to find food and water!”.
In addition to the ability to migrate between far distance places, birds change their color throughout the year. All the time. Now, that is what has me stumped in accurate identification many times. But I like a challenge! And as one expert bird guide and author assures us, it’s alright to say, “I don’t know!!!”
Next post, we will look at how, and why, birds change color throughout the year. And why some bird species have a wider variation in colors than other species.
Until then, what are these two birds? 😉