A Little Local “Leaf Peeping”

Recent reports say that parts of Eastern Canada have spectacular fall colours this year, and the pursuit of “leaf peeping”, as it’s known back East – viewing and photographing fall colours –  is in full swing.

With our temperatures dropping to single digits, and the season’s first snow dusting the North Shore Mountains this past weekend, it’s the right time to do a little local “leaf peeping.” While we don’t have whole mountainsides covered with deciduous trees – our dominant trees are evergreens – we still have some real beauty to enjoy. We just have to look a little closer.

Deer Lake Park – looking north

Our native red-leaved species include the red-osier dogwood above – a common shrub in our parks, and the vine maple, a small tree which can be a spectacular contrast to the dark greens of our forest conifers.

Vine maple – Deer Lake forest

So why do some trees’ leaves turn red, and others yellow? It’s all about the chemistry of leaves. As the amount of daylight declines in the fall, leaves stop making food through photosynthesis. The food maker, the green stuff of leaves, is chlorophyll. In fall it stops being replaced by the tree or shrub, and slowly degrades and disappears from the leaves revealing the yellow pigments previously hidden.

Here’s an example of a big-leafed maple – our large, native maple – showing the process in action. As the green chlorophyll disappears, the yellow pigment is revealed.

In technical terms, the degrading chlorophyll slowly fades to reveal the xanthophyll pigments in the leaves. For trees with red fall leaves, a slightly different, but related process takes place. The decline in chlorophyll is accompanied by the production of anthocyanins (red pigments) related to the end-of-season increase in sugar production and storage in the trees. Red-osier dogwood shows this process well.

Our bright red street trees undergo the same changes, but most of them are Eastern imports planted for easy maintenance, and of course for their spectacular fall colours.

So while we don’t have mountainsides of red, we have our fall beauty on a smaller scale.

Big leaf maple and red-osier dogwood – Deer Lake Park

And finally, just to show the birds haven’t been ignored this week, here’s a vine maple nicely setting off the blue of a Steller’s Jay. You’ll have to look closely to see it. Can’t see it? Click the image to enlarge it, and take another look. When I took the picture, I didn’t know I’d captured the bird too!

Cache Grab for Winter

If Stellar’s Jays think like we do (they probably don’t), then I can imagine the one above is pretty pleased with itself. Holding a peanut in its bill from my backyard feeder, this bird is about to fly off with its prize to hide it away in a Deer Lake forest. In ornithological lingo, it’s caching food, for use in winter. When temperatures are low, when food is a lot harder to come by and maintaining body heat requires extra calories, these birds will return to their caches to fuel up. It’s an avian lay-away plan for winter.

Black-capped Chickadees, like the one above, cache smaller items such as the sunflower seeds they collect from our feeders. Peanuts, good for Steller’s Jays, are much too large for this little bird to cache. If you have a feeder at your house, I expect you’ve noticed a lot more activity lately, and that your seed supply is diminishing more rapidly than usual.

At this time of year chickadees are visiting our feeders so often they couldn’t possibly be eating all the seed they’re carrying away. Of course, they’re not. Like the Steller’s Jays, they are on a major caching binge. It’s that time of year, and there’s a flurry of activity to store a back-up food supply for winter.

Chestnut-backed Chickadees (below), our other common local chickadee, are also madly gathering seeds to cache.

Sometimes birds put a lot of food in a single location, but more frequently they cache small numbers in each place, and very often they cache single food items separately. So you can anticipate the problem here. Most of us have one or two sets of house or car keys, but if you’re like me, knowing where they are at any one time is often a major challenge. Where are my keys?! So how can these bird-brains remember the location of hundreds of different caches? How can they remember their cache locations even when they’re under the snow?

The answer is – birds are just better at some mental activities than mammals, including humans. A little humbling isn’t it? But they do have a nice built-in biological advantage over us. They regrow part of their brain each year to accomplish these astounding feats of memory. The hippocampus, the part of their brain involved in spatial memory, regrows brain cells at this time of year. Old cells are replaced by new ones, and old memories are replaced by new, as this year’s cache locations are laid-down for later retrieval. Couldn’t we all do with a little bit of that ability? I’m really sure a new brain, or at least part of it, would really help in so many ways!

Of course it’s not all hard work. Sometimes it’s break time, as this Chestnut-backed Chickadee above is showing. Not every seed is cached; sometimes it’s just eaten. The bird here has peeled off the outer husk of a sunflower seed, and is just finishing up the energy-rich kernel inside.

But all is not plain-sailing in the caching business. Not every bird is focussed on their own caching. The smart ones out there are looking about to take advantage of the unwary. Most jays and chickadees are careful not to let other birds see where they’re hiding their cache. On the other hand, some birds don’t seem to pay attention at all to others watching them. All that hard work, and their carefully cached food is quickly stolen and hidden elsewhere by the wily cache thief. A cache grab indeed.