We all understand why birds of the Northern Hemisphere fly south in the fall. When the temperatures drop in Michigan, and the lakes are covered with ice, most birds have found a warmer place in the south. Michigan has many so-called “snowbirds” in the human population who leave us in November to go to Florida’s sunny shores. They come back in the spring to enjoy Michigan summers and because they have family here. The question is, why do birds fly north in spring? Couldn’t they save a lot of trouble by just staying in the south all year?
The answer to that question is food. The fact is that tropical areas simply don’t have enough insects to provide the protein that birds need to feed their chicks. When birds are in the south, they survive by eating berries, fruits, and nectar. None of those foods provide much protein. The time when birds return to the north coincides with the explosion of insects in the spring. They can enjoy less competition and longer days while dining on insects in the north.
The question remains as to how the birds know this? How do they know that they can benefit by traveling hundreds or thousands of miles in the spring? Why do the birds have the urge to fly north at the time that benefits them as well as the ecological systems they help to support? In other words, why do birds fly north in spring? The answer is that it’s built into their genes.
God’s view of Earth and the systems that make it work is far greater than ours. We are beginning to understand how many things, such as bird migration, must happen for the system of life to exist. It also speaks to us about how important it is that we take care of what God has given us.
Would you like to guess how many bugs are in your home? In the fall of 2017 researchers from the California Academy of Sciences published a survey of the bugs in 50 homes in and around Raleigh, North Carolina. The researchers took 10,000 samples from basements, bedrooms, kitchens, and attics. They identified 579 species from the 304 families of arthropods known to science. Arthropods include insects, mites and, spiders.
The researchers found ants, carpet beetles, gall midges, and cobweb spiders in 100% of the homes. In many of the houses, they found booklice, dark-winged fungus gnats, cellar spiders, scuttle flies, and dust mites. Misha Leong who was the lead author of the study says that most homes contain hundreds if not thousands of individual arthropods.
It is interesting that as people move toward buying organic and buying in bulk, they are increasing the bugs in their homes. Indian meal moths, for example, can contaminate oatmeal or chew through a sweater. They lay eggs in our food and closets, and the larvae chew through packaging leaving a mess of silk and frass (waste) behind. If we use the food quickly enough we eat the eggs, and since they don’t hurt us, we don’t even know they are there.
The reality is that we have and will always have lots of bugs in our homes. Many of them are beneficial to us. Booklice, for example, eat fungi and mold. Spiders eat insects and other harmful agents including flies and mosquitoes. Harmful spiders like the black widow and brown recluse are rare. Studies have also shown that many of our chronic diseases are related to our failure to be exposed to biological diversity. Leong says, “Rooms with more kinds of arthropods may be healthier rooms.”
It is easy for humans to minimize the design that is needed for life to exist on Earth. How do you feed massive numbers of birds, especially in the spring when winter has taken away most of their food sources, and their food needs are maximized as they lay eggs and feed baby birds? In the past scientists have shrugged their shoulders and imagined that there are food sources we don’t recognize that fill this gap until the summer season generates sufficient seeds and insects to sustain the growing populations. Similar problems exist for many other animals like bats that depend on insects for their nutritional needs.
In the April 2017 issue of Scientific American (page 84), there is an interesting report about previously unknown migrations of insects. We have known about monarch butterflies for some time, but this study by British researchers shows that migrations of insects are massive. Over southern Britain alone there are 3.3 trillion insects migrating. That is an average of 3200 tons of bugs moving through the skies over Britain every year. The study also reports that similar patterns have been observed in Texas, India, and China.
The complexity of this migration is astounding. Insects don’t live long enough for one bug to complete the migration. Researchers found that in some cases six generations were involved to complete a migration. The insects do not just get randomly blown about. They travel in a well-programmed pattern taking advantage of wind direction and speed. The elevation at which they fly to get the strongest support for their journey is carefully chosen. For a number of reasons, spring migrations are different from fall migrations.
Over the years we have presented data on some amazing migrations. We have had several discussions about the Arctic tern and how it makes its incredible 12,000-mile journey. Research has shown that the Arctic tern uses multiple cues including magnetism, sight, smell, and even sound. We have also talked about whales, salmon, and sea turtles and the way they benefit multiple ecosystems by their migrations. Now we have a new migration that has just been discovered and is equivalent to 20,000 flying reindeer. It’s migrating insects.
According to the study, 2-5 million migrating insects fly over the United Kingdom each year. The study is reported in the December 23, 2016, issue of Science by a team headed by Jason Chapman. Tracking these arthropods involves the use of special radar designed to detect insects. The team estimates that the total biomass of these arthropods is 3200 tons which is 7.7 times more than the biomass of the songbirds in the same area. These are tiny creatures with some of them weighing less than 10 milligrams.
Chapman notes that these arthropods are not just accidentally caught up in the wind. Some of them climb to the top of a plant to launch their flight. Some stand on tiptoe and put out silk until the wind catches them and carries them away. The animals only launch when the wind is to the north from May to June, and in August and September, they launch when the wind blows to the south. Chapman concludes “these arthropods must have some kind of built-in compass plus a preferred direction and the genetics that change that preference as they or their offspring make the return migration.“