May 2009 – Page 2 – Seabrooke Leckie

Roly-poly fish beds

A couple of days ago, Dan took Raven down to our dock to throw the stick into the water a few times for her. Since becoming a bonafide water dog, she takes to the water like a fish and it’s easy to give her a good exercise while simply standing on the dock tossing sticks. While we have some small misgivings about her splashing around in the shallows there, it seems better than having her running around loose in the woods. We’re simply not capable of giving her sufficient exercise through walks on a leash, she’s just got too much energy to burn.

We do, however, make an effort to keep her to the north side of our bay. Last summer, when we moved in, we noticed some bare circular patches in the gravelly shallows along the south edge of the bay. We knew right away that these were spawning beds, though without the fish on them we couldn’t say for which species.

With the weather, and therefore the water, beginning to warm up, it’s about the right time for most species to start spawning. A couple of weeks ago we noticed some activity in the shallows around our dock, a bit of splashing and some dorsal fins poking up from the water’s surface. This occurred for two or three days, and then the water was quiet again. We never did determine which species was involved there, though they were smaller fish than the pike I’d seen earlier in the spring.

We’d been keeping a casual eye on the spawning beds off our shoreline, and knew they would return eventually, so it didn’t come as too much of a surprise when Dan called up to me that afternoon, “The fish are bedding!” I was quick to grab my camera and head down to try for some photos, unable to quell a little bit of excitement about the event, having never observed it before. There’s also something neat about it happening in your own backyard.

I ran off a few dozen photos, trying for at least one or two that might show the fish clearly enough to be able to identify the species. Unfortunately, it was a somewhat breezy day, and the ripples on the water’s surface distorted the fish’s shape, making it difficult to tell (at least in the photo) that the object was even a fish, much less of what sort. Complicating matters was that the water’s surface reflected the clouds in the sky, causing sufficient glare to wash out the objects below the surface. I did my best, but didn’t come out with much.

I returned this afternoon, hoping that the slightly calmer wind conditions might allow me to get a better photo. Unfortunately, the water’s surface was still as washed out as the first time I tried. There were some areas near the shore that reflected the dark canopies of the overhanging trees, and in these spots one could clearly see down to the bottom – but naturally, there were no fish beds there. Where the beds were left me, standing on the shore, at too oblique and angle to avoid the glare. The fish are very skittish, dashing off the bed at the first sign of shadow, so I wouldn’t even be able to take the canoe over. Ah well. You get the idea.

I was only able to definitively determine the species of one of these fish, and it was just by chance, as I was reviewing the photos. Notice that in this one you can see that his eye is bright red (I’ve saturated the colours here to accentuate it). In our waters, there’s only one species of fish with a bright red eye: Rock Bass, Ambloplites rupestris. Below is a photo of a Rock Bass taken last summer, where you can better see the eye and scale pattern than when it’s in the water. It’s amazing how camouflaged fish are in the water, considering what they look like when you pull them out.

For most fish, when they start to spawn depends on the water temperature, and so the exact timing may vary from lake to lake, depending on the depth of the water and various local conditions. Pike are the earliest here, spawning when the temperature of the shallows reaches 10 oC (50 oF), usually not long after ice-out. Rock Bass need slightly warmer temperatures, at around 15 oC (60 oF). The sunfishes, Pumpkinseed and Bluegill, need the water to be at least 21 oC (70 oF).

The division in temperature requirements means that probably, for the most part, the species are temporally separated from one another in when they spawn, and you’re not likely to find sunfish spawning with Rock Bass, for instance. I’m not sure if they’ll use the same beds once the other fish clear out, or if everybody makes their own, but clearly they clean up and reuse beds from previous years since all of the ones along our shore are occupied this spring.

Depending on the species, a single female fish can lay thousands of eggs. Female Rock Bass lay an average of 5,000 eggs, with high counts reaching 11,000 per individual. Bluegills, however, may lay as many as 38,000 eggs per female. Since sometimes two females may lay in the same bed, there can be up to 60,000 eggs in a single bed. Bluegills, unlike other fish, have the potential to overpopulate a lake as a result, and when things start to get a bit crowded growth rates slow down. I don’t think the other species have the same problem. In the case of all species, the majority of those eggs are going to be eaten before they ever reach maturity.

The beds are guarded by the male fish, once the female has laid her eggs and left. He protects it from predators, never straying far, and also aerates the eggs by fanning water of them with his fins. The eggs hatch in two to five days, partly depending on water temperatures and the particular species in question, during which time the male eats only what happens to enter the area around his spawning bed. This is why catching fish on spawning beds is so easy. Although fishing spawning Largemouth Bass and other large sport fish is illegal, sunfish are open all year. Fortunately, they don’t appeal to very many people. I suppose the easiest way to confirm the identity of the species, if I really wanted to know, however, would simply be to pull out my fishing rod.

I suppose I’ll have to keep an eye on the beds, watch for when these guys leave and disperse, and see if I notice anyone else come in to take their place.

The wolf among the flock

Heading down to the dock this afternoon I noticed this large aggregation of caterpillars on the trunk of a relatively young tree. The caterpillars are Forest Tent Caterpillars, Malacosoma disstria, related to the Eastern Tent Caterpillars, Malacosoma americanum, that are the stereotypical tent-builders commonly associated with the name. Whereas Easterns tend to be found in more open areas, associated with successional species such as chokecherries, crabapples, apples, Black Cherry, and other members of that family, Forests, as the name implies, are found in more mature growth, and are generally associated with maples, basswood, oak, and other forest trees.

The caterpillars are easily told apart by the pale line down their back, which is solid in Easterns and broken in Forests. But perhaps the most distinct difference is that Easterns build large tents to live in, while Forests do not; they will congregate together on leaves or trunks, and they leave silk trails along their foraging routes, just as Easterns do, but they don’t build complex silk structures (though they may weave a silken mat that they sit on).

This makes them something of a sitting duck (or ducks), exposed out in the open. The Easterns can retreat into their nest, and spend their non-foraging time under the protective layers of the silk, but the Forests don’t have that option. There’s not much they can do about predation from birds or the like (although I don’t know about the presence of urcticating hairs or unpalatable taste), but they have evolved a mechanism to protect themselves from parasitic flies.

Last spring I discovered a caterpillar with a fly egg behind its head. These larvae, when they hatch, burrow into the caterpillar and feed off it from the inside (without killing it right away). The flies lay their egg at the back of the head where the caterpillar can’t remove it. To say that the caterpillar “wants” to avoid being laid on is an understatement, and so they have evolved to twitch their front ends rapidly from side to side when there’s a threat. I caught these ones twitching; the photos were taken at 3 frames per second (so the above series represents one second).

It was only after I’d run off a series of photos of the twitching caterpillars that I happened to notice the fly, though she’s there in that top photo, too, if you look carefully (it would have to be a she if it were laying eggs). It was wandering along the edge of the caterpillar colony, and the caterpillars were all freaked out, twitching back and forth like mad. Surprisingly, though, only about half of them were doing this, the other half were just sitting still. Perhaps saving their energy, since the fly wasn’t actually targeting them?

There is a particular species of fly that specifically targets Forest Tents: Sarcophaga aldrichi, often called the Friendly Fly for its habit of landing on people without biting (probably interested in the salt in your sweat). Friendly Flies are the number one form of population control for Forest Tents, and their numbers fluctuate in sync with the caterpillars’. In years of high numbers of caterpillars, the Friendly Flies will be abundant, and some people have given them the name Government Fly on the (erroneous) assumption that the government had released the flies to control the caterpillars.

It would logically make sense that this fly wandering about a Forest Tent colony and freaking all the caterpillars out would be a Friendly Fly, except that it doesn’t match any of the photos I’ve found of that species. Flies are one of those groups that really throw me for a loop when trying to figure out an identification, so I can’t even place it in a family reliably. I’ve submitted the photos to BugGuide.net and am waiting to see if someone there is able to ID it.

At one point the fly got a little too close to a couple of very upset caterpillars, and they turned on it, appearing to bite at it. The fly squirmed through their attack and moved away. I didn’t see it make any moves to deposit an egg on a host while I was there, it mostly stuck to the edges of the colony. I finally accidentally disturbed it and caused it to fly away as I was trying to brace my hand on the tree trunk to support my somewhat heavy camera/lens combination (it didn’t help that it was very windy out today). Considering how flighty most flies are, though, this one was fairly docile.

I’ll have to keep an eye on that tent caterpillar colony over the next few days, and see whether the fly either returns, or I notice any caterpillars carrying little white spheres behind their heads. It’s interesting just to encounter a particular species and to know something about their life history, but it’s even cooler to come across a behaviour or species interaction like this.

Today at Kingsford – My very own road

Spotted while driving out to Perth this afternoon – they even remembered the ‘e’!

Monday Miscellany

This weekend was spent visiting my family, at my parents’ new place east of Brockville. I packed up Raven and headed out on Friday, and then returned home late today. It was a tri-purpose gathering, combining a belated Mother’s Day with two birthdays (mine and my sister’s, which are two days apart, usually on Mother’s Day weekend). My entire immediate family was there, an uncommon event these days as we’re spread across nearly half of southern Ontario, with close to 450 km (280 miles) separating the two furthest people (the closest two are still an hour’s drive apart). It was a really nice weekend, full of family and good times, but I must admit that in four days I didn’t do a smidge of naturalizing. I barely did any birding, even; aside from about 15 minutes spent with the binoculars Saturday afternoon, my only birding was what I noticed singing or caught a glimpse of while wandering around. My camera spent the weekend in its bag.

So my Monday Miscellany is on the short side this week. The first photo is from mid-week. The Rose-breasted Grosbeaks, including this stunning male, have been making regular trips to the feeders. I’ve been seeing more of the females than the males, although the males can be heard regularly singing in the vicinity. They’re big fans of the sunflower seeds, so we’ve been continuing to fill our feeders even though the winter birds have all mostly departed. I always look forward to the return of these guys to the feeders in spring.

The Ruby-throated Hummingbirds have settled in to the area, I think. My mom had at least two females visiting her feeder, and I heard a male doing a U-display at one point. I have yet to see a female here, but then again, I was away all weekend. It astounds me how fast these little birds can beat their wings when flying (an average of 50 beats per second, but substantially higher in certain situations). Watching them hover in the air as they pause to scan their surroundings is like magic. They should be starting to nest soon; also magic? the amazingly tiny nests they build, and the even more amazingly tiny eggs they lay in them.

On the particularly rainy day we had last week, I noticed this little guy sitting on the small sumac tree that’s near the feeders in front of our house. He would feed, then sit on the branch for a while, then return to feed, then back to the branch. I guess with the weather so cool and wet, he didn’t want to waste a lot of energy flying all over the place, so he stuck close to a guaranteed food source.

On my birthday Dan and I went out in the afternoon to visit one of the MAPS sites. It’s the site we have to paddle in to, and at the launch point where we were putting the boat in to the water, I noticed a large patch of vibrantly coloured bushes. The area where they were growing seemed to be under water, and it was hard to tell if the plants were victims of higher-than-normal water levels, or if they were swamp or other wetland bushes. Their colours, and those of many of the small saplings growing among them, really reminded me of the autumn landscape.

These could almost have gone in to the “Wings of the day” W week post. I’ve noticed both dragon- and damselflies to be becoming much more abundant recently. The above, a Springtime Darner (Basiaeschna janata), and below, a Common Baskettail (Epitheca cynosura), were both observed along a stretch of dirt road slightly to the north. They were flying along the edge of the road, in the low, open area between the hard-packed dirt and the forest. Many dragonflies are territorial, and will patrol up and down a stretch of road, path, forest or pond edge, or other open area, as they watch for intruders and look for females. Indeed, these two were doing just that, sweeping up and down the road and then periodically landing on a tree or twig to sun and “recharge”.

W Week – Wings of the day

White-striped Black, Trichodezia albovittata

To wrap up my W week I thought I’d post the counterpart of yesterday’s Wings of the Night: whereas yesterday was moths, today is butterflies. Well, mostly. Two butterflies and a diurnal moth. The latter is above, with Raven’s foot for scale. That wasn’t actually intentional; I noticed this little black-and-white lep fluttering along the roadside, and I had Raven sit-stay while I chased it around in circles waiting for it to land. It gravitated toward Raven’s black fur, warmed by the sun, and tried landing in a couple of spots on her haunches before settling in front of her paw. Even there, it didn’t stay long, just long enough for me to snap a couple of blurry shots as it trembled its wings.

It’s a White-striped Black, a diurnal species of wet areas within deciduous woodlands. Its larval foodplant is jewelweed, aka touch-me-not, part of the genus Impatiens (though I’m not sure that it would be interested in the ones you grow in your garden). Common, it can be seen most of the year, across most of the continent, from Alaska to California to the Atlantic.

Spring Azure, Celastrina ladon

Not far up the road I discovered this beautiful little blue guy. Although I regularly seem little blue butterflies flitting about in the spring, they hardly ever seem to come to rest anywhere, and when they do, you barely have time to get your camera to your eye before they’re off again. This was the first rather obliging individual I’ve encountered this spring, and the closer look allowed me to identify it as a Spring Azure. Another species that’s found nearly continent-wide, it’s generally associated with edges or openings in forests.

Spring Azures, Celastrina ladon

Larva are associated with dogwood, meadowsweet and New Jersey Tea, but the adults will nectar on a reasonably wide variety of flowers. I found these ones obsessed with a patch of Sessile Bellwort. They never flew far from it, and when they landed (always with their wings shut, of course), it would always be to visit the flowers on these plants. Interestingly, they spent as much time at the base of the flowers as elsewhere, and I wondered if they were working their proboscis between the petals to get at the nectar rather than coming up the long way from the mouth of the flower.

Olympia Marble, Euchloe olympia

And finally, Olympia Marble. This is a species I had never seen before; in fact, I had never seen any marble before, so when I came across these while out hiking with Dan through one of our MAPS sites, I had no idea what it was. The patterning on the underside of the hindwing is distinct, and beautiful, a rich yellow-green. Their eyes were coloured to match.

They’re found in open woodlands and open habitats such as grassy knolls and meadows, and alvars and sand dunes. Add to that treed rock barrens, which is where I found one pair of these. It was the male that caught my eye, as he fluttered in the air around a stationary female who sat on the top of a wildflower stem. After a few moments he came to rest beside her, and then after a few moments more he took off and flew away. The female, meanwhile, continued to sit there, and I was able to get quite close to her. The first photo was actually of a second individual that I encountered along an open road allowance later that afternoon.

Presumably the male mated with the female and then headed off, leaving the female to lay her eggs on her own. The species is fairly specific to Hedge Mustard and various types of rockcress. The adults fly in late spring and then die, leaving behind just their progeny to carry on. Interestingly, the eggs aren’t laid on the leaves of the plant, but rather the flower buds, with a single egg per bud. The caterpillars, when they hatch out, eat the flowers and seeds but ignore the leaves.

For more wings, of both night and day but all lacking clubbed antennae, pop over to NAMBI for the latest edition of The Moth and Me. Although it was due up a couple of days ago, being busy with family has slowed me down so that I didn’t meet the intended deadline. Ah well – better late than never!