The foliage is starting to change colors and along with that, the fall migrations have started. It is a topic I have always found fascinating, and in this day and age when Google can give you all of the answers, this is still a topic that has scientists baffled. We do not have all the answers to the puzzle.

I have had the great joy to observe the migration of turkey vultures from very close by for about 14 years.

Let me backtrack a little so you can better understand the facts and appreciate the irony of this story.

Nineteen years ago I was living in the traditional large tract house with a pool in Valencia Hills. My children were starting to leave for college, and the house had been partly rebuilt after the earthquake. All was well, and we were not thinking about moving until the day I walked my dog along a street in Newhall and followed the flight of a turkey vulture that landed in a tree in a deep backyard.

The house was empty and for sale, so I went into the garden. All the way down in the deep garden was a turkey vulture roost.

What a wonderful discovery it was for me. My family was not sure if I was losing my mind when I proposed to move to this small house without a pool but with a turkey vulture roost – but move we did.

Turkey vulture

For 14 years, I studied the habits of those turkey vultures, taking notes on their behavior and sending the information to the turkey vulture organizations that gather such statistics.

A roost is simply a gathering place where the turkey vultures meet about one hour before sunset, leaving it again around one hour after sunrise. There again, not much is understood about the need for a roost. In our roost, we would typically have 15 to 19 of the large birds each day, but come the first week of September, the number would slowly increase each day to 40 or 45. The last week of September, one morning they would all fly in formation as a single, large kettle – a flight pattern where they make a spiral – and they would leave on their migration.

They would come back with strict accuracy every year, the first week of January. The nesting season is long, and they needed that time for the babies to grow strong enough for next fall.

Where would they go? Your guess is as good as mine. Perhaps as far as Mexico, but there is no way to know for sure.

The plot thickens. My eyes always follow each turkey vulture I see in the sky, and during the winter when “my” vultures were gone, I still saw plenty of turkey vultures flying around. Why were they still here? Well, some are living along the coast where the climate is mild year around; also some of the local turkey vultures seen in the winter could come from northern California or even Oregon. Only birds that have been tagged and checked on a regular basis can tell us where they have been. As the tagging is stressful for a bird, it is not an action taken lightly.

This has nothing to do with migration, but you might be interested to know the rest of the story. One summer, a major limb from the eucalyptus in my backyard broke with a huge, frightening noise and a lot of damage to the tree. The roost did not feel safe anymore. The turkey vultures still used it until September, but they did not come back in January. I was sad and disappointed, but it made sense.

There is a humorous, ironic and almost impossible-to-believe twist to the story: I walk on a regular basis on the paseo near my old house. Would you believe that two years ago I noticed a turkey vulture roost in three big pine trees just across from my old house? I had to catch my breath when my old house went on the market last May. No, we did not move again, but I sure felt the joke was on me.

Fall migration is an exciting time, and it starts as early as July for many shore birds. It can happen as late as December for shorter-distance land birds such as sparrows and black birds, raptors, waterfowl and sea birds.

Bird migration is complex. It is difficult to establish “rules,” because even within the same species, their path and strategies may differ according to the weather.

I will tentatively separate them into two groups: birds that fly during the day and birds that fly during the night (diurnal and nocturnal migrants). Some birds use warm thermal currents in the air to soar (raptor, pelicans); they will fly during the day. Long-distance migratory land birds like warblers, sparrows and thrushes migrate at night, or at least they start the flight at dusk. If they fly during the night, they will drop out during the day, eating and resting for the next flight.

However, some birds do a one-flight migration. They go from Canada to South America nonstop.

Nocturnal migration is difficult to observe, but some sites along coastlines and ridges with southerly views are known by the Audubon Society and many of the members come to observe the migration. Many of the species have a special night call. In California, when the Santa Ana winds are blowing, the direction of the wind is from east to west, so it can be a good time to watch migrants along the coast as birds are pushed off shore and try to orient themselves back along the coast.

If we look at our local birds, to find out which migrate and which do not, you almost have to take one specie at a time and examine the situation.

Dark-eyed junco

The dark-eyed junco is not seen in the summer here but is seen at higher altitudes. Altitude migrants are birds that can be seen at a slightly higher altitude in the summer but come down to the valleys in the winter. However, some Oregon juncos come from the north and migrate to the south. Hairy woodpeckers are not migratory, but some individuals that nest at higher altitudes go to the lower valleys and to the coast to enjoy winter there. Seems like a good choice to me.

Seeing the first white-crowned sparrow was always a true and welcomed sign that winter was finally here. But while doing my research, I learned there is a subspecies that is a permanent resident in some parts of the coast. I would assume the white-crowned sparrows we see in Santa Clarita come from British Columbia or northern California, but the more I learn about migrations, the more I see the complexity of it all, and I do not think I can be certain of much of anything. You have to wonder at the incredible mystery and achievement that takes place during those migrations.

I will finish with the champion migratory bird, the Arctic tern. Would you believe this small bird flies 24,000 miles round-trip from its breeding ground in Alaska to Antarctica and back? It spends two months in Antarctica to rest – and eat a lot, I would hope – and then it is already time to fly back north. As it lives about 34 years, that means that it has the opportunity to fly 800,000 miles in its lifetime. No, I did not get mixed up and add extra zeros.

Enjoy the fall and all the mysteries of the new season.

Evelyne Vandersande has been a docent at the Placerita Canyon Nature Center for 28 years. She lives in Newhall.