The Marvelous in Nature

Five worthy blogs

First, I should start off by announcing that the latest I and the Bird is up at Wrennaissance Reflections. Wren has categorized the various posts into all the different aspects that make up “the joy of birds.” Definitely worth a read, pop over and check it out!

Beth of Beth’s Stories did me the great honour of choosing my blog of the 100-odd she follows to include in a blog-recognition meme. At the very least I’d like to thank her and return the linkage (worth checking out, if you don’t know her already – she’s one of my daily reads). But further to that, it’s a good opportunity to recognize some other worthy blogs.

The rules of the meme are thus:

1. Choose a max of 5 blogs (we could all probably list our entire blogroll, but then you might as well just point people at your blogroll).
2. Four of the 5 have to be dedicated followers of your blog.
3. One has to be someone new or recently new to your blog and live in another part of the world (the definition of “another part of the world” is left to your discretion).
4. You must link back to whoever gave you the award (fair’s fair! If they’re sending traffic your way, the least you can do is thank them by sending traffic back theirs. Hopefully you also like their blog, too).

Since I discovered the amazing convenience of Bloglines.com, a blog feed reader that keeps track of all your blogs for you and lets you know when new posts go up, so that you don’t have to check dozens of pages every day, since I discovered that the list of blogs I follow has inched up to 50. I could easily follow more, and will probably end up adding additional blogs to the reader because there’s so much good writing out there. And that’s just for nature blogs. If you have any doubt about the prolificity of nature blogs, simply check out the Nature Blog Network. When I signed up to it, when the network was just a couple weeks old, back in February, I was right at the bottom, #68 I think. Now, there are 440 blogs in the network, and more being added every day. My blog bobs up and down on the list, sometimes in the 50s, sometimes in the 60s, once as high as #48, at its lowest about #105. It uses the average of the last 10 days to calculate your average number of visits, so it can vary a fair bit from one day to the next. I think a fair number of my visitors are people who Google for information on various species, but I like to think that many (most?) are dedicated readers of my blog.

Some of the blogs on my reader are very well read by others, and some have a much more limited following. The latter are generally because they’re relatively new, rather than due to lack of content (I wouldn’t invest the time in following a blog that didn’t have interesting content – and on dial-up, it is something of a time investment!). The ones at the bottom of the Nature Blog Network list are there either because they don’t post often or don’t post good content, or they have good content but few views simply because they haven’t been around long enough to be discovered and develop a readership.

The five I’m choosing, therefore, are all younger or less frequently followed blogs that I think are worthy of a stronger readership (currently they all rank on the 4th page of the Nature Blog Network, or lower – they deserve to be higher than that!). They have all, at one time or another, commented on my blog so I know they do or have read it periodically. I encourage all my readers to check them out, and leave a comment if you like what you read.

In no particular order:

Huckleberry Days – If you like my blog, you’ll enjoy reading this one. Styled in the same vein, profiling different species and phenomenon of interest, this blog fulfills the #3 rule as well – Huckleberry found me within the last month (or at least started commenting then), and lives on the far side of the continent, out in British Columbia.

Beetles in the Bush – Ted is a regular reader, but also maintains an excellent blog of his own. He posts less frequently than some, but this is where the convenience of the reader comes in – you’ll never miss a post because you forgot to check in. As the name implies, the blog is all about the wonderful world of beetles. And there’s no shortage of them to talk about!

From the Faraway, Nearby – One of my favourite things about this blog is the address – a nod to a favourite cartoon of mine when I was young, the Adventures of Tintin. Indeed, T.R. (as noted in his profile, but is it so hard to guess his name?) travels for a living, and his exploits are chronicled here. Most recently, he had the good fortune to be able to visit China to attend the Olympic Games. Lots of good photos and interesting stories.

Roundtop Ruminations – Carolyn lives out in the forested mountains of Pennsylvania. Her observations of life in the Pennsylvanian forests are interesting and enjoyable to read, and offer a different perspective on rural life than most people get.

Voice of the Turtle – And finally, after long deliberation on who the last blog should be, I settled on this one. Although not a nature blog, Turtle is a gifted writer, and her entries are sprinkled with frequent stories and limericks. Her corgis and family figure prominently in her posts, she runs occasional contests (prize: a 500-word story on the subject of your choice), and generally offers an upbeat view on life. She’s also one of my most dedicated readers.

All worthy recipients; I hope you go check them out!

Hammerhead, harpoon-tongue

We’ve had a Hairy Woodpecker (Picoides villosus) hanging around the house for the last week or two. For the most part it’s remained some distance away, up high or hidden by leaves, hard to observe but easy to detect through its tap-tap-tapping as it chips away bark looking for insects. Hairy Woodpeckers have always struck me as being less common than the smaller Downy Woodpeckers, as I find I don’t encounter them nearly as often when birding, and I’ve always found it a treat to have one hanging about.

The second edition of the Atlas of the Breeding Birds of Ontario includes maps of abundance levels throughout the province for most species (anything that can be regularly detected on point counts), and it confirms this assessment. It indicates that the Downy is at its peak abundance, up to 7 birds per 25 point counts (the standard unit of measurement for the abundance maps) through most of the Carolinian forest region extending southwest from Toronto, and patchily throughout the rest of the province. The Hairy, meanwhile, is encountered at a rate of less than 1 bird per 25 point counts through the same region. Even in the areas where it reaches peak abundance, through the more rugged Canadian Shield, its abundance is still only a maximum of 3 birds per 25 point counts – less than half of what the Downy reaches in its peak zones.

Here in the Frontenac Axis we’re right in one of those peak abundance zones for Hairys (it’s incidentally also a good spot for Downy and Pileated, likely simply due to all the deciduous and mixed forest around here). We hear the other guys around, but the only one to spend much time on our property has been the Hairy. Although the Hairy is noticeably larger than the Downy, without aid of a size reference, the best way to tell them apart is by the bill: a Hairy’s bill is about the same length as his head, while a Downy’s is only half the size of his head and has a rather petite look to it. Incidentally, although the two species look virtually identical, they’re not all that closely related. Their similar patterning is a wonderful example of convergent evolution – two species acheiving the same result by two separate, independent evolutionary paths.

Yesterday morning she was not far off from the deck, and she was unusually low. The sexes are told apart by red at the nape of the crown in males, while the back of the head on females is all black. This is true also for Downys, and virtually all other woodpecker species have some form of dimorphism between the sexes, although the particular feather region in question varies.

I watched her hopping up the tree trunk. There are a few groups of trunk-foragers, which have all developed their own special niches. Woodpeckers are borers, in that they’ll drill holes or chip off bark to get at the bugs sequestered underneath. They hang upright off the side of the tree to do this, using their sharp little claws to grip the bark and their stiff tail feathers like a prop. Hopefully you’ll never have occassion to handle a wild bird, since that probably means it’s run into a window or some other human structure, but should you have the unfortunate (for the bird) opportunity to find and handle one, or happen to visit a banding operation where they catch a (live, healthy) woodpecker, take a moment to check out these specialized features. Of all the non-predatory birds I’ve handled, woodpeckers have by far the sharpest nails. In this photo she’s caught mid-hop, pushing off with her powerful feet and leaping vertically, then grabbing the trunk again with her feet.

The other two groups are nuthatches, which have the peculiar habit of descending down a tree head-first as they forage, and creepers, which go the other direction, up and upright. Both of these groups prod in the cracks of bark and under loose pieces, looking for insects that are hiding there. Their different foraging directions means they can exploit cracks that go unnoticed by the other group.

You can just see her tongue between her two mandibles as she probes here for an insect. Woodpeckers have amazing adaptations to their foraging strategy. The first is the length of their tongue. The grubs they target make tunnels into the bark, which the birds chip or drill into the bark to expose. Once they’ve found a tunnel, the grub can sometimes be down the tunnel at the other end. The bird inserts its tongue, which it uses like a spear to snag the grub from the bottom of its burrow. The woodpecker’s tongue has a stiff cartilaginous tip, covered in sharp little barbs, perfect for pulling things back that are out of reach.

And the bird’s tongue is looong. The tongue is a cross between the muscular structure we humans have, and a rigid bony structure. It’s got a long, branching Y-shaped bone, called the hyoid, that splits at the back of the throat and wraps up behind the head, sometimes ending as far forward as the eye socket or nostril, where it’s secured by elastic tissue. There are muscles that are paired with the horns of the Y, affixed to the back of the jaw, and running to the tip of the hyoid bone. Contraction of these muscles pulls the tips of the hyoid bone around the back of the head and back down toward the mouth, and in doing so, pushes the tongue out the mouth. When the muscles relax, the elastic tissue returns the bone to its original position, and the tongue is pulled back in.

If you part a woodpecker’s feathers on the back of its head you can usually see the hyoid bones and muscles under the skin there. Humans have a hyoid apparatus, too, but ours is very much reduced and not used in the same way (ours is mostly support, and a base for some muscles). Because of the length of these hyoid bones wrapping around the back of its skull, a woodpecker is capable of extending its tongue twice the length of its head, useful when the prey is buried deep. Check out some of the photos that Hilton Pond Center has posted at this link – pretty amazing. The incredible structure and mechanism that operates the tongue (also described on Hilton Pond’s site) are sometimes used as an example against evolution, on the basis that such a wonderfully complex system couldn’t have evolved on its own. Really, though, it’s just a bigger, fancier version of the tongue structure found in chickens. A baby woodpecker starts out with hyoid horns that resemble a chicken’s, and they grow into woodpecker-length as the baby grows.

The other adaptation a woodpecker has evolved has to do with the hammering. Can you just imagine the sort of headache you would have if you had to do this for your dinner every day? A woodpecker’s beak, when it’s hammering against a tree, is moving at about 7 meters per second – the equivalent of about 25 km/h or 15.6 mph – which would be sufficient to cause brain damage in humans when met with an abrupt stop (the force of which would be about 1000 times that of gravity). Most animals, ourselves included, have brains that sort of “float” in the brain cavity, surrounded by a thin layer of fluid and membranes, which allows the brain to keep moving and “crash” into the bone when the skull suddenly stops, causing bruising and brain damage. A woodpecker’s is tightly packed inside the skull by spongy bone that protects it, so it stops when the skull stops. This page notes a couple additional secondary adaptations that also help in reducing the impact of the impacts.

But what about it’s beak? Here the bird is using it to chip away some loosened wood. The beak is used as a multitude of tools, including crowbar and chisel, but it’s mostly used as a drill (or hammer, depending on how you look at it). Surely the force of such constant and repeated impacts (up to 20 times per second) would weaken or shatter it. With a normal bird’s beak it probably would, but woodpeckers have special grooves that run at an angle to the direction of force, which strengthen the structure. It’s like trying to stand a piece of paper up on its thin side. Put a crease in it and it’s suddenly got much more strength and rigidity.

I watched the Hairy work the trees for a bit. She was remarkably docile, and seemed unperturbed by my being there. I ran off well over 100 photos of her poking about the trees, but won’t share them all here. Here’s a few more from the collection, though.

She stops for a quick preen. Here she’s reaching back to a little gland that’s at the base of the tail, on their top surface (at the bottom of their back), which has the fancy name of uropygial gland, but the more casual name of oil gland or preen gland. If you look at it up close (again on that unfortunate window-strike, or the luckier banding capture), it looks a bit like a wart, yellow and slightly greasy looking. It produces an oil that’s incredibly important to birds for waterproofing. When you see a bird running its beak through its feathers it’s doing one of two things. If it’s simply working the feathers then it’s reorganizing all the barbs and smoothing them out so they create a flat surface (ruffled barbs disrupt aerodynamics and mean the bird burns more energy when flying; also they can allow more heat/temperature loss). However, if it’s reaching around to its tail regularly, it’s squeezing the gland to produce oil that it then works through the feathers for waterproofing.

She showed interest in this cavity. I thought it was a little late for her to still be nesting, but not impossible, and it would explain why she’d been hanging around the area so closely.

She paused and looked around, then looked inside again, before going in.

The hole was fairly deep, and she slipped down, first just her tail feathers protruding, then disappearing entirely.

She was only gone a moment before her head popped back up, though. She did this twice during the span that I watched. Neither time did she seem to go in with food. The second time she came out with what appeared to be a wood chip. I didn’t hear any cheeping, and baby woodpeckers are notoriously noisy, so if there were any in there I would’ve heard. But she wasn’t staying in, so she must not have eggs. I had to conclude that she didn’t have a nest after all, but maybe was scoping out potential sites for next year?

Then she checked out this little knot. And pulled out a grub. Maybe she was just looking for food after all.

I’d been watching her a good twenty minutes or so, running off constant photos, curiously following where she went and what she was doing, when she headed up this slanted branch. She swung around to its underside, and then as she twisted her head to probe into a crack in the bark…

…I could see red in his crown! Yes, all along it had been a boy. Young males, males that were hatched this summer, won’t have that red nape yet, but they will have red speckled through the crown as this one does. It’s funny that I didn’t notice it at all in the 20 minutes prior. Especially since, once I got all the photos onto my computer, it was incredibly obvious in so many of the photos. I had to pick through them carefully to make sure I chose ones that didn’t show any red for the images above! Females can actually show a bit of red in the crown as juveniles, but it’s rarely extensive (this is on the intermediate side of extensive, and it could be hard to call this either way, but I’d lean toward boy). I’ll blame my lack of attention on the lighting. Or being so caught up in watching his behaviour. Or something.

Black and orange but green all over

A couple weeks ago I discovered this bug crawling among my herb planter on the deck. Although it wasn’t large, about the size of your index fingernail, it was vibrantly coloured, and really rather hard to miss. I recognized it as being a bug. That is, a true bug, a member of the order Hemiptera, rather than a bug in the colloquial sense of the word (though it is also that, of course). The dual use of the word can cause some confusion, and is the reason that the word “true” generally prefaces “bug” when speaking in a specific sense.

The Hemiptera include a wide variety of insects, from cicadas to leafhoppers to shield bugs and others. The group is defined by the presence of a long stiff “beak” or proboscis, which is really the mouthparts and mandibles of other insects evolved and modified into a long tube. They use this beak to pierce plants for food, usually sap. Also, the name Hemiptera reflects their special wing structure – “hemi” means half, and “pteron” means wing. Rather than the familiar membranous wings of most insects, the basal half of Hemipteran wings is opaque and hardened.

I also knew that it was probably a shield bug, based on its shape (which also gives the group, the family Pentatomidae, its common name). The shield bugs are also known as stink bugs because they possess glands on the underside of their middle segments that, when disturbed, are capable of releasing a pungent liquid that contains cyanide compounds. Fortunately, I didn’t have the opportunity to experience it firsthand, as none of the bugs I encountered did this. Interestingly, the bright colours of the nymph are suggestive of aposematic colouration, and I wonder if it’s a reflection of these cyanide compounds.

However, I was confused when it came to species. I couldn’t spot anything that quite matched in my guide, and when I looked closely at the bug, the apparent lack of wings seemed odd. It seemed like it had a raised button right in the middle of its back. I saw a few more, here walking around the rim of my water fountain, others among the blackberry canes in front of the house; it seemed reasonably common, at least here.

Some poking around on BugGuide.net eventually revealed them to be nymphs, which is why I wasn’t sure what they were, and why they didn’t appear to have wings. I discovered this mangled mess hanging off a leaf of my sunflower plant yesterday. I believe it’s the cast-off skin of one of my mystery bugs.

The species is the Green Stink Bug, usually labeled Acrosternum hilare. Based on the BugGuide.net page, the bright nymphs seem to be in their 5th instar (larval stage), which is the final one. In each larval stage they change colour and pattern just slightly. Some will become nearly green in their final instar, while others will remain these bright colours.

Yesterday evening I ran my moth lights, and found these guys who had come in to the sheet. It’s the adult form of the species, and is larger than the nymph, maybe the size of my thumbnail. I hadn’t seen any even just the night prior, so perhaps one of the ones at the sheet is the owner of the shed skin hanging from my sunflower. They’re dramatically different than the larval form, and although the species is depicted in the Kaufman guide to insects, the nymph isn’t, so I didn’t recognize it. Kaufman does an admiral job with the guide, but there’s still only so much one can reasonably depict in a single guide to insects.

The Green Stink Bug is a common bug through much of North America. It feeds on a wide variety of plants, and is found in a range of habitats, throughout most of the year. Here in the north they just have one brood, but in southern, warmer areas they can have two. These nymphs and adults probably belonged to our one hatch here. Their eggs are attached to the underside of a leaf in two rows, and are often described as “keg-shaped”.

Incidentally, in the above photo you’re able to see the “half-wings”, with the lower half of the front wings looking like it’s protruding from a cover like a beetle’s elytra (really, the “cover” here is the upper half of the front wing). The wings are termed hemelytra for their resemblence to the true elytra of beetles.

There’s a second species in the south that looks very similar to this, but has red-striped antennae instead of black. Both can be significant agricultural nuisances given their wide range of food preferences. Often they’ll develop a taste for seeds, and will target growing crops such as corn, soybeans, beans, peas, tomatoes and others, before the veggies are yet ripe (doesn’t go over well with farmers, understandably). When they’re not aggravating crop farmers, they’re off tormenting orchard growers, as they’ll happily feed on the stems and foliage of other plants, particularly apple, cherry, orange and peach trees. They are one of the guilty culprits responsible for “catfacing” on fruit such as peaches and tomatoes.

They’re a particularly hardy bug and don’t respond to pesticides. However, they use a particular pheromone to communicate that can be artificially produced and used to draw adults away from crop areas. They’re also parasitized by a tachinid fly, but that would be a bit harder to ensure it worked.

It’s interesting to get to see the life cycle of something like that (even if I did miss out on the egg and early stages). All too often we get a fleeting glimpse of the insect, usually in its adult form, and are left to wonder about the rest of its life history. Ruth over at Body, Soul and Spirit has a really cool video of a monarch caterpillar shucking its skin and turning into the pupa that precedes the chrysalis, which I highly recommend checking out! It took me over half an hour to download on my dial-up connection, but was very much worth the wait once it was completely loaded and I got to watch it.

Anatomy of a sunset

When I was involved in bird research projects, I would usually be up and arriving at the research site in the pre-dawn twilight to set up our equipment. One of the best things about having to get up so early – okay, the only thing – is that you would get to enjoy the sunrise every day (on those days where the sky wasn’t clouded over, anyway). I have some beautiful sunrise photos from that period. Pinks seem to predominate, though I have a number of striking oranges and reds, as well.

I was mildly disappointed that our new house faced east, such that we wouldn’t see the sunsets across the water, because I did really enjoy watching the colours of the sky. I knew that I was unlikely to be up often enough, at least in the summer and fall, to catch the morning sunrise that we would be able to see from our deck, but I am always up for sunset. I used to admire some that we would see from the apartment in Toronto, but would never take a photo. It just wasn’t an ideal setting, with all the buildings and power lines and everything else in the way.

I guess I hadn’t expected to be out in the boat so often here, or out so late. But some of the best fishing can be had at dusk, so we’ve frequently gone out just after dinner and stayed out till after the sun has gone down, navigating our return by the silhouettes of the trees and the reflection of the water, and tracking our location by the illuminated houses of our neighbours.

I think the best sunrise and sunset photos are those taken across water. It has the dual advantage of a large open space to give you a better view of the sky, as well as the reflective properties of the water that replicate the colours below. Since I’ve been fishing for the smaller guys, using jigs instead of cast-out lures, I really prefer to fish during the daylight hours; early morning is my favourite, when the lake is still and quiet, though it unfortunately requires setting the alarm to be sure I’m up. It’s easier to go out in the evening, you’re up anyway. My favourite part of being out late, after I can’t see my lure in the water anymore, is watching the sun go down and the sky light up.

The reason that the sky isn’t just the usual blue during sunrise and set is because of the angle the sun’s rays are traveling through the atmosphere at. If you move six hours east (in the case of sunrise) or west (for sunset), the sky will be blue under the sun there. It’s the same sun, just the angle has changed. At all angles, the light waves are encountering particles in the atmosphere, and are breaking up into their different components and scattering. The ones that head down to the ground are in the blue spectrum, which is why the sky looks blue. The reds and oranges get scattered sideways. At the very acute angles that the sun’s rays are viewed when the sun is near the horizon, it’s these reds and oranges that reach our eyes.

Almost inevitably, sunsets are more dramatic and more brightly coloured than sunrises. Since the sun is entering and leaving the horizon at the same angles, it’s the amount of dust and other particulates (like pollution) that affect the colours. The more particles in the atmosphere intercepting light waves, the more light that gets broken up and scattered, the brighter the sunrise and sunset.

The reason sunrises tend to be paler, then, is because there’s less in the air. During the course of the day, activity by people puts dust, dirt and pollution into the air; it settles out, to some extent, at night. Also compounding this effect is that as the sun warms the earth it creates convection currents – winds – that stir things up into the atmosphere as well. Clouds and moisture can contribute to bright displays, which is likely the meaning behind “Red sky at morning, sailors take warning; red sky at night, sailor’s delight.” A red sky at night is just a reflection of the day’s dust, but a red sky in the morning is probably reflecting off the particles associated with a storm system.

Of course, the sky’s colours can also be affected by natural events such as volcanic eruptions, large wildfires, or dust storms, which throw immense amounts of dust and particulates into the atmosphere, too much to settle out quickly. Some events are so large in scale, such as the eruption of Krakatoa in 1883, as to affect the atmosphere of the entire globe. Not surprisingly, though, and perhaps rather thankfully, these events are rare.

What we think of as a typical sunset doesn’t occur on planets other than our own. Differences in atmosphere composition and distance to the sun mean that the light refracts differently than it does in our own atmosphere. This is also why a blue sky is a novelty to our planet, and why the moon has no daytime sky at all (it lacks an atmosphere). High winds on Mars kick up sufficient dust high enough into the atmosphere to sometimes create a lingering red sunset that can last as long as two hours after the sun sinks below the horizon. However, without this dust in the air, the sunset there isn’t much to look at.

Another interesting sunset phenomenon is called the green flash. I’ve never seen it, and I’m unlikely to here. It happens just as the sun dips over the horizon, right at the cusp. The light waves break and scatter in just such a way, and the atmosphere is just dense enough at that angle, that for a brief period the sun’s rays glow green. They’re usually only seen on an unobstructed horizon, such as over a large lake or the ocean, or in the great plains. This is because the light needs to be traveling through the densest part of the atmosphere to create the effect, and this usually occurs close to the ground. Given all the forest surrounding us here I probably won’t be seeing one any time soon.

The problem with taking photos of things like sunsets is that you can amass a huge collection of them, since you’re tempted to photograph each and every one, because they’re all different. But then what do you do with them all? Well, I can share a few of my favourites from the last few weeks here, in any case.

The purple monster

It’s late August, and one of the most maligned flowers to be introduced to North America is blooming in wetlands and damp areas across the continent. The plant is Purple Loosestrife, Lythrum salicaria, and coinciding with the start of its blooming period I’ve been seeing posts on the colourful purple flowers popping up on many of the blogs I read. The general sentiment toward the plant is acknowledgment of its pretty purple blooms but antagonism towards its presence.

There have been big promotional campaigns toward its eradication. I remember as a kid my sisters and I joined my father pulling up some plants that had seeded themselves at the edges of our little swamp and the pond across the road (actually, what stands out most clearly about that afternoon was walking down my neighbour’s driveway to say hello to the woman, who was also pulling loosestrife, while swinging a just-pulled loosestrife plant, with a big clod of dirt at its base, by my side like a walking stick, and her alarmed reaction admonishing me as it would spread seeds). The website PurpleLoosestrife.org has the subheading, “A Beautiful Killer”. Talk about melodramatic! But it is the promoted notion of the plant.

But why loosestrife, over all the other widespread and incredibly invasive plants? The wildflowers in our roadsides and meadows are probably more than half introduced species (if my own observations are any indication), and yet no one’s crying for any of their metaphorical heads. Why has there been no campaigns to control Butter-and-eggs, or Viper’s Bugloss, for instance? There’s no shortage of invasive species; Invasive.org lists 694 exotic plant and 228 non-native insect species on their website as well as 43 other organisms. What makes loosestrife such a target? One reason might simply be its visibility, the bright purple flowers that really stand out in a wetland.

Interestingly, I’ve read a number of articles that have accused the anglers and hunters organizations as being the primary proponents of loosestrife eradication. Do a Google search for “purple loosestrife control” and the #2 site to come up is the page for OFAH (Ontario Federation of Anglers and Hunters) and #3 is PurpleLoosestrife.org, which, when you look closely, is hosted by Ducks Unlimited Canada. The latter is the #5 site returned by the search, and many of the others on the first page are government or conservation authority sites (I’ll refrain from painting all of these with the same brush, but will state that within the couple of authorities that I’ve had insider insight into, the majority of employees are themselves either hunters or anglers). Why would these organizations take such an interest in Purple Loosestrife? (Conversely, compare a search for Eurasian Watermilfoil, another terribly invasive aquatic species, and only one of the top ten – OFAH – is a hunting/fishing organization.) Only they know for sure, but the argument I’ve seen presented is that loosestrife creates denser habitat that’s harder for anglers and hunters to navigate through, and reduces their productivity on outings. (To be fair, that could all be a bunch of bunk presented by someone with anti-hunting sentiments; that’s the downside of the internet, it’s harder to tell fact from fiction.)

Of course, that’s not the story that’s given for controlling the spread of the species. Whether it was through anglers associations, governments, or other media lines, the general picture presented to the public is one of a ruthless invader, moving into and decimating wetlands (as illustrated by the PurpleLoosestrife.org subheader). We are told that if left unchecked it will completely take over wetlands at the expense of native species, forming near monocultures of a plant that’s non-native and therefore practically unusable by our native fauna. We’re lead to believe that if we don’t do something right away, that sprig of purple flowers you see at the edge of the cattail patch will, within a few years, have wiped the whole stand off the map.

Okay, maybe it’s my turn to lean towards the melodramatic, but it’s not that far from the truth. A lot of research has gone in to loosestrife control, and no fewer than four non-native loosestrife predators (two beetles and two weevils) have been approved for introduction across North America as a biocontrol method. OFAH states that these insects have been established at over 300 release sites across Ontario alone. They also state that these insects have no other known food items, and so their population will be limited by the availability of loosestrife, with the plant and insect eventually establishing a relatively stable relationship at low numbers. (This may be true. Of course, there’s also this saying – most famously stated by Dr. Ian Malcolm in Jurassic Park – that nature will find a way.)

Of course, it all begs the question: Is all this hoopla really warranted? Is it really as bad as they say? In university, a chapter of one of my courses, Conservation Biology, examined the danger of accepting unproven hypotheses – that is, making assumptions without doing the background research. The example the professor presented for this section of the class? Purple Loosestrife. I don’t remember a lot of what I learned in university, but those lectures really stuck with me. Over the years and through several moves, however, my course notes got misplaced, so when I decided I wanted to do a post on Purple Loosestrife, I emailed my course prof and asked for some of the material pertaining to that segment of his course. He generously obliged with six papers he happened to have on hand on his computer.

The papers are all dated within the last 10 years. They examine a number of common (and prior to that, unproven) assumptions regarding the plants, and actually carry out manipulative experiments (meaning that they manipulate the different variables involved in order to pinpoint the truth of the situation) or quantification studies (where they take samples from plots representing a range of loosestrife conditions, from absent to monoculture) to prove or disprove these assumptions.

The results show a number of things. The first and perhaps most important is that loosestrife, like so many introduced species, requires disturbed habitat to become established. Loosestrife seedlings would only take root and prosper in plots that were experimentally cleared of reed canary grass to simulate herbivore foraging disturbance; 53% of seeds sowed in such plots became established, while 0% became established in non-disturbed plots. A second study showed that in undisturbed habitats, loosestrife was unable to invade and establish itself, as seedlings can’t compete with established, mature native vegetation. However, once a disturbance creates a situation where the native vegetation is removed, allowing the seedlings a window of opportunity to get established, the mature loosestrife plants are able to prevent the young native plants from growing in again. This is where the problem really lies.

This information says to me that the wetlands where loosestrife is found are perhaps not the healthiest to begin with, if they are experiencing so much disturbance as to allow the invader to spread and turn into a monoculture. It could be a natural disturbance – say, severe harvesting of cattail roots by muskrats – but I rather suspect non-natural disturbances such as boats are also at least partially to blame. Perhaps it’s just coincidence, but in our shallow lake the corridors where the motorboats rip back and forth from one end of the lake to the other lack much vegetation on the lake bottom, while areas that don’t get much motorized traffic grow thick and weedy. But these are just my hypotheses, unproven by any sort of scientific research, of course!

As for the claim that loosestrife reduces local biodiversity, it simply isn’t true. One study showed that plant diversity in invaded habitats was actually higher than it was in stands without the loosestrife (and no, it’s not simply because the loosestrife is the additional species). They found that species richness also increased with increasing abundance of loosestrife. They pointed out that this raised the question as to whether loosestrife naturally preferred to invade more diverse stands, or if some factor of the loosestrife’s presence created that diversity; they don’t have an answer, but do point out that previous studies didn’t seem to show a preference for invading stands of either higher or lower diversity.

A second study of the same thing, but in a different location, showed no significant difference between plots with and without loosestrife, and no relationship between species diversity and loosestrife abundance. They did, however, observe that several species were significantly more likely to be found in plots containing purple loosestrife, but no species were significantly more likely to occur in plots without it (again, whether this is due to characteristics of the stand that make it appeal more to both loosestrife and the other species, or if it’s a direct result of the loosestrife’s presence, is the subject for future studies).

Another study looked at aquatic invertebrate diversity between plots with and without loosestrife, and found no significant differences, although they did note that the invertebrates in loosestrife stands tended to be a tad smaller than those found in plots without loosestrife. Whether this is due to dietary deficiencies, some characteristic of the habitat allowing larger bugs to get picked off leaving just small ones, or a local selective pressure toward overall smaller bug sizes, is for a future research project.

I’m pretty sure that, aside from our afternoon plucking plants that one year when I was young, the wetlands by my parents’ have had no control measures, no removal crews, no beetle releases. They also have no muskrats, no people, and no boats. And, they have very little Purple Loosestrife. Even fifteen years later there are still just the odd few plants here and there, mostly along the edge of the road; far from the monotypic stands broadly predicted among all the doom and gloom surrounding the species. Here at our new home, we have a couple plants that are blooming, standing singly at distances from each other, adding a bright splash of colour but hardly threatening the ecosystem.

I think the truth is somewhere in between. I suspect that there are instances, highly disturbed areas that suffer heavy herbivore and/or human activity, that will require human intervention to keep the opportunistic loosestrife from moving in to the compromised wetland. However, I don’t think, based on the research to date, the classifications the plant has received (“noxious weed”, “beautiful killer”, etc) are necessarily warranted. If we humans hadn’t muddled around with the wetlands in the first place, I strongly doubt that loosestrife would be as widespread and abundant as it is today; the low abundance of the plant in relatively untouched areas is evidence of this. Something to ponder next time you see these purple flowers growing at your local patch.

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