There are Canada Geese at the bottom of our garden. Not fairies, Canada Geese. Actually, most days I think I would prefer fairies, but that’s jumping ahead of things. We need to start at the beginning.
When we first arrived in Pfafftown (pronounced paaf-town) there were a few Canada Geese on the lake (perhaps I should call it a pond, as ‘lake’ sounds too grand). They are elegant birds, and the whole scene looked rather idyllic. I was reminded of being on the edge of the Chesapeake in October many years before, when the Canada Geese were migrating south, but on that occasion, there were millions of them. This was June, and I wondered if these few were going south or north.
Animal migration is one of the more amazing features of our world. I can’t help myself, I’ve decided this is time for a short discussion on migration and going home!
Most people know about salmon. Salmon spawn in the upper reaches of rivers, usually having to perform dramatic feats like leaping up waterfalls, and just eluding (or failing to escape) the grasp of a hungry grizzly bear. Upstream, the young salmon go through three stages; for the first year, called fry, they stay close to where they were born; for the next one or two years they usually remain in the freshwater reaches of the river, exploring further afield; and finally, now called smolt, they migrate down to the sea. Look, there’s a lot more terminology, and it’s all for specialists: as far as this account is concerned, after 2-3 years, they are off to the ocean.
Now we get to interesting part. After living in the sea for a time, often travelling huge distances, they decide to return to the exact same river and stream where they were born. How do they do it? Scientists believe salmon use the Earth’s magnetic fields like a map. Unaided, without parents to guide them, they appear to remember the magnetic fields they encountered when they first entered the sea as youngsters and navigate their way back to precisely the same place where they were born, to spawn and in most cases to die.[i]
Well, that was the theory. Now, more recent research suggests they journey home in a group, and “by being in groups, they can share information and pool their abilities to navigate and orient and by doing so the group is much more likely to get home than if the group was smaller or the individual is traveling by itself and the onus of getting to the right spot would all be on the individual”. [ii] As the research suggests: “So you can imagine, fish that are headed to the Kvichak versus the Nushagak, if it’s better to be with your Nushagak group, how do you know that you’re with the right group? Salmon have an amazing ability to use pheromones and essentially … they’re smelling their way home once they’re in freshwater.” [iii] All done by a sense of smell!!
Another stellar group in the world of migrants are Monarch butterflies. These travellers will fly around two and half thousand miles to spend their winter hibernation in Mexico and some parts of Southern California where it is warm all year long. If they normally live in the Eastern states, east of the Rocky Mountains, they will migrate to Mexico and hibernate in oyamel fir trees. If the Monarch butterflies live west of the Rocky Mountains, then they hibernate in and around Pacific Grove, California in eucalyptus trees. As far as researchers know, Monarch butterflies are the only insects that migrate to a warmer climate 2,500 miles away each year. More amazing, Monarch butterflies use the very same trees each and every year when they migrate. Amazing? Yes, because they aren’t the same butterflies that were there last year! These are the fourth generation of butterflies, so how do they know the right trees in which to hibernate?
There’s been a lot of research on how these butterflies know where to go. Canadian researchers have been studying Monarch butterflies which fly from the eastern Canadian provinces to gather, by the millions, in Mexican groves that they have never seen before. Recent experiments suggest they navigate using an internal compass calibrated to the sun. “Given how incredibly complex and fascinating the monarch migration is, it’s quite remarkable that the system to get down to the overwintering grounds is relatively simple … and if they get blown off course it appears they are using the Rockies and Appalachians and the coastlines as a funnel down toward Mexico. They don’t necessarily need a map – if they have a compass and they have the major landscape features to guide them there, that seems to be sufficient.” [iv]
However, there’s still one part of the story that remains to be solved. Once the butterflies get to the right part of Mexico, how do they find the 10 or so groves where they settle in the thousands, turning the forest a spectacular orange? It seems that might be – by their sense of smell!!
Time to get back to Canada Geese. Canada geese migrate south for various reasons. Basically, they prefer open water where they can swim away from predators and dive for food, and if lakes and ponds freeze over in the winter, they must leave for warmer areas. The peak time for migration south is during September and October. Because Canada geese like to return to the places they were born, they will fly back north during the spring.
Hey, you might not have known those birds at the end of our garden are pretty remarkable! During migration, Canada geese fly in a V formation, with each bird in line flying a little bit higher than the goose in front of it. Why? One theory is it allows the lead goose to break the headwind, allowing the birds behind to fly in the “draft”. As we often hear when they are around, Canada geese communicate when flying by honking, announcing it is time to shift positions during their flight in order to take turns breaking the headwind and reducing fatigue.
They don’t dawdle. Canada geese fly at an average speed of about 40 miles per hour when migrating but may increase their speed to 70 miles per hour if they catch a strong tailwind. Like those butterflies, migrations can be as long as 2,000 to 3,000 miles, and the geese are capable of flying up to 1,500 miles in a single day if the weather is good. During their long migrations, Canada geese typically fly at an altitude of 2,000 to 8,000 feet, although I read aircraft pilots have reported sightings of Canada geese at altitudes of up to 9,000 feet. [v]
Got a bit over-excited there! Back to how they do it. Research has been shown birds use several orientation “tools”. First, like the Monarch butterflies, they have a built-in compass, and can use the sun, which means that they permanently “know” what time it is, allowing them to sense the right direction on the basis of the sun’s position. There is evidence they are also able to feel ultraviolet rays which penetrate the clouds but are invisible for human beings. Even nocturnal birds use the position of the sun at sunset to know their position, and some appear to use the stars for navigation. Of course, birds also use their knowledge of the landscape: they follow rivers, valleys or roads, or locate themselves with particular mountain peaks. Finally, they have some kind of built-in clock that tells them it is time to migrate.[vi] Research on Canada Geese suggests they learn the migration path from their parents: perhaps for them topology is the critical issue.
Just for your interest (??), like the Monarchs, another tool used by birds is the earth’s magnetic field. Some birds, like pigeons, have a small zone in their brain made of magnetite (magnetic mineral), just like a small compass.[vii] Finally, and you knew this was coming, Canada Geese have an excellent sense of smell, and it is quite possible this plays a role in their ability to navigate …
That was background. Not all Canada geese migrate, and many are year-round residents found in urban areas where their natural predators have diminished, and where there are ponds or man-made bodies of water. We didn’t know that when we first saw them in Pfafftown. Now we know much more. These birds don’t go home after the winter migration. Cotswold Road is their home. They have one home, not two, unlike the case for the millions that migrate every year.
As far as I can tell, we have several permanent residents. There are four I see regularly on our lawn. One has a badly damaged wing and might have been attacked by the large snapping turtle that lurks in the pond. This bird can fly but avoids doing so. Another has a damaged foot (the snapping turtle again?). The two other permanents seem to be healthy. One is a male, taller than all the others, and is obviously in charge. How do I know that? When I go to shoo them off the grass, he’s the one that honks, takes his time as he whooshes the others away, and gives me a nasty look. The final member of the group is a smaller bird, a female. Since Canada Geese are monogamous, I assume she is the male bird’s partner.
There are others, but these are the ones I see most often. I do see another goose from time to time with a damaged wing, but this is not as bad as the other bird’s. Occasionally, I will see a solitary bird, an unusual sight: I’m not sure, but I think it was the mate of a goose whose body we once saw on the other side of our pond. However, it is difficult to be certain about the total number of residents, as several birds seem to come and go. I suspect many use both our pond and a few others around us as their territory. There might be twenty resident birds, but there could be as many as fifty. Just to be clear, in addition to our residents, we do get transients in the spring and autumn, and I have counted over a hundred birds on our lawn from time to time.
They are not the only birds who live on our pond. We have at least one family of Mallards. We also have a group of extremely ugly Muscovy Ducks, the result of an enthusiastic neighbour adding a couple to join the other birds – and they bred!
After that long meander, let’s get back to the beginning: why might I prefer fairies at the bottom of our garden? It’s all about smell. Canada Geese are prodigious poopers, and their poop stinks! It’s on our lawn, it’s on our driveway from the road to the house, and on a bad day, it’s on the bottom of a shoe. I guess they feel at home, pooping everywhere. Those Canada Geese might have looked elegant when we arrived, but they are a PEST, leaving evidence everywhere they go as they wander around their home territory!!
Home. Thinking about that reminded me Shelducks are migratory birds, too. Recently, I consulted the definitive work, ‘The Shelduck’,[viii] to find out more. Like many other varieties, Shelducks moult, and when moulting most are unable to fly, for a period that runs from July to September (in the northern hemisphere). British Shelducks, (the best kind, obviously), will either go north to parts of Scotland during this time, but many go over to Heligoland. You don’t know where that is? It is a part of Germany, comprising a couple of very small islands in the North Sea, close to the coast of Germany, and also near to the western seaboard of Denmark.
For Shelducks, is home where they live most of the time, or is it where they go to moult? The UK or Heligoland?
For Sheldrakes, migratory over longer periods of time, where is home? As an example of this tiny tribe, where is home for me? East Anglia, where Sheldrakes can first be identified in the records several hundred years ago? The UK, where I was born and lived for nearly 30 years? Australia, where I lived for a longer time, nearly 36 years, and where all our children live? I’ve only been in the US for 8 years, so that can’t be the place, can it? I find the concept of home somewhat strange. Home for me is where I am, right now, and it can change as soon as I move. “Home is where the heart is”, the place for which you feel the deepest affection. Home for me is where I am living with Linda, and that could be anywhere. [ix]
There are Canada Geese at the bottom of our garden. Actually, right now they are all on the other side of the pond. I think my next door neighbour has acquired some kind of geese-scarer. I heard this horrible sound earlier today, a screech, almost like a metallic high-pitched scream which I thought was actually a creature of some kind. It gave me a fright. Then I heard it again, a few hours later, and I noticed all the Canada Geese had scooted off to the other side of the lake. Perhaps there won’t be Canada Geese at the bottom of my garden any longer.
What will happen to their sense of home? Do I care? One thing is quite clear to me: I could do without the poop!
[i] True for all Pacific species of salmon, and some Atlantic species, too.
[ii] https://medium.com/@GrrlScientist/salmon-scent-and-going-home-again-grrlscientist-57cffde055ae
[iii] Ibid
[iv] <http://www.cbc.ca/news/technology/how-monarch-butterflies-find-their-way-to-mexico-1.1302747>
[v] <https://americanexpedition.us/learn-about-wildlife/canada-goose-facts-information-photos/>
[vi] See Tim Birkhead, The Wisdom of Birds, 2008, Bloomsbury, especially pages 163-171
[vii] For more on magnetism and heaps more interesting information, see Tim Birkhead again. His ‘Bird Sense’, (2012 Walker, a Bloomsbury subsidiary), pages 175-178, gives an excellent overview of this strange ability.
[viii] You should have a copy at home, but, in case not: I J Patterson, The Shelduck, Cambridge University Press, 1982
[ix] A Pew research survey found “Home means different things to different people. Among U.S.-born adults who have lived in more than one community, nearly four-in-ten (38%) say the place they consider home isn’t where they’re living now. But there’s a wide range of definitions of “home” among Americans who have lived in at least one place besides their original hometown: 26% say it’s where they were born or raised; 22% say it’s where they live now; 18% say it’s where they have lived the longest; 15% say it’s where their family comes from; and 4% say it’s where they went to high school. < http://www.pewsocialtrends.org/2008/12/17/who-moves-who-stays-put-wheres-home/>
