Bug Bioblitz!

by Carl Strang

(This is a cross posting from the Nature Notes blog at the Observe Your Preserve website). On Wednesday, Naturalist Nikki  Dahlin and I ventured to Winfield School to lead our first complementary program to a teacher participating in the Observe Your Preserve advisory panel. Madeleine Ciezak’s second graders, joined by another second grade class, experienced a mini bioblitz focused on bugs, loosely defined by us as arthropods and expanded by the kids to invertebrates generally.

We surveyed a public park across the street from the school, which you can see in the background.

The idea was to assess the park’s bug biodiversity on that afternoon, in other words to see how many different kinds of bugs we could find. We divided the kids into 6 teams, 3 of which focused on the lawn and sidewalks while 3 explored trees, bushes and other plants. After 15 minutes, the teams switched habitats and surveyed for another 15 minutes. Each team had a teacher or parent with them, and Nikki and I rotated among them and facilitated.

Here Nikki assists with a bug. We helped with questions that came up and made occasional suggestions, but mainly stayed out of the way and let the kids explore.

Usually one can expect that any given program or task will engage most but not all kids. No problem here, though.

Perhaps the option to be a data recorder or live specimen minder broadened the activity enough to appeal to all the learning styles represented in those classes. On the other hand, maybe bugs are so interesting to kids that age that engagement is a given.

Before we left the classroom we asked the kids to predict how many kinds of bugs we would find. Estimates ranged from 20 to millions, but 75 seemed to be a rough median. As we gave directions upon arriving at the park we asked them to predict which habitat type (lawn vs. other plants) would have the most bugs. They predicted other plants.

Protocols were not always followed exactly, but the main point was the experience, so we limited our coaching and accepted the results essentially as the kids recorded them.

After giving everyone a chance to see what all the groups caught, we answered questions about some of the more interesting species and had the kids release their specimens. Back in the classroom we presented the compiled results, and continued a discussion of bugs that could have gone on indefinitely but brought us to the end of the school day. This general format can be modified and adapted to a variety of locations and groups of organisms. Such experiences give life to a range of concepts from habitat and biodiversity to mimicry, life history, anatomy and physiology, and other lessons that cannot be fully grasped from book study.

Graphic Assessments

by Carl Strang

The amphibian trapping season at Mayslake Forest Preserve is done for the year. A painful back strain stopped me a week early (I mention this so you’ll know why blog postings may be thin for a time). The main purpose of the trapping effort is to determine which amphibian species occur on the preserve, particularly salamanders which, unlike frogs and toads, are silent and hidden most of the year. As I posted earlier, in this second year the traps did indeed reveal the presence of tiger salamanders. In addition, though, the traps have caught a variety of larger invertebrates.

One example is the predaceous diving beetle Dytiscus verticalis. I photographed this one on its back to show the brown color on the underside of the abdomen, a species identification feature.

As time goes on, the traps continue to catch animals, but new species appear less and less often. This can be rendered graphically.

This graph combines the two years’ data. I keep records of all individuals caught, which allows me to see how new species have appeared as the total catch has grown.

As you can see, there appears to be a leveling off at the current total of 11 species. Keep in mind that this is not the total number of animal species in the stream corridor marsh, just those that can be caught in the traps. Such data usually are converted to logarithms in ecological analyses.

The same data as in the previous graph, converted to their logarithms.

Again there seems to be a leveling-off, but not so dramatic. Another approach to species richness is to consider the accumulation of species according to sampling effort.

Here the same species are shown being added as the trap-days accumulate.

This graph reveals something significant. Can you see how there appear to be two episodes of the species count leveling, at 4 and at 11 species? That first leveling represents the latter part of last year’s trapping. If I had been content with those results, I would have drawn the conclusion that the marsh contains around 4 species susceptible to these traps. But this year’s results were different, adding not only the tiger salamander but a few new invertebrates as well as two frog species. Also, I did not catch two of the species I caught last year. Here is the same data set converted to logs.

This graph gives a hint of why the logarithmic conversion is done. It takes out some of the misleading tendencies that appeared in the unconverted data.

From this final graph I conclude that I need to continue trapping at least another year. I will sense that I have an idea of the marsh’s species richness when the log-log graph of trapping effort levels off. Even without this graphical analysis I would have wanted to continue trapping, however. Something the graphs don’t show is the dramatic difference in the kinds of animals caught each year. Where last year the sampling was dominated by predaceous diving beetles, this year there were few of them but a lot of white river crayfish. Clearly there are some dynamic changes occurring between years, and I want to see what future years hold.

Are Siskins Nesting at Mayslake?

by Carl Strang

This past winter brought good numbers of winter finches down from the North. The last time that happened, Mayslake was a beneficiary with pine siskins all winter and occasional visits by groups of white-winged crossbills to the assorted conifers around the mansion. This year I was disappointed that such visitations were not repeated. Then, in early spring, siskins began to appear.

Pine siskins are close relatives of goldfinches, with many similar vocalizations, but browner and streaked down the front.

The siskins haven’t left. They have hung around in some past springs, too, and though I haven’t seen any young, again I am suspicious that they may be nesting. Last week I saw a squabble between a couple pairs that looked territorial. Their nests are small (4 inches in diameter according to my references), and won’t be easy to spot in the dense foliage of a conifer. If they are neatniks, there won’t be telltale bits of grass hanging down. Still, every time I walk past those conifers I am looking up, trying to spot a nest. If I find one I’ll let you know. Siskins are mainly birds of the North, but they are known to nest in Illinois.

White River Crayfish Young

by Carl Strang

This week brings the end to another year’s running of amphibian traps in the stream corridor marsh at Mayslake Forest Preserve. As was the case last year, I have caught relatively few amphibians compared to the number of invertebrates. This year the majority of captures have been, specifically, white river crayfish (a species of marshes and other still waters in flood plains adjacent to streams).

A mature white river crayfish is impressive in its red coloration.

Last year I caught only adults. This year brought all sizes, and I was able to get a sense of how they change with age (my reference gave only verbal descriptions). Young ones have small pincers, and are an olive color with distinctive black spots on the sides.

Immature white river crayfish, around 1.5 inches long.

As they get bigger the spots fade, the pincers get a little bigger, but the color remains olive.

This one is around 3 inches long.

I keep watching for some variation that might hint at a young grassland crayfish among the white river ones, but so far none have turned up.

It Takes a Village…

by Carl Strang

This year, Mayslake Forest Preserve’s pair of great horned owls decided to use a squirrel nest for their own breeding attempt. In my first sweep of the preserve I did not find the nest, though I did see the male bird on watch, and thought that perhaps the nest was in one of two large tree cavities in that part of the preserve. I generally discount squirrel nests, in part because I never had seen an owl nest on such a platform, and in part because owls prefer something more substantial. A few days later I noticed a suspiciously flattened squirrel nest in that area, and sure enough, there was mom owl in incubation posture.

The supportive array of pine branches apparently made this squirrel nest seem more solid than most.

I informed Mayslake’s superb team of restoration volunteers, knowing they would want to be judicious in their activity around the nest. Some days later one of their leaders, Jacqui Gleason, came into my office with the news that a baby owl was on the ground under the nest.

The baby was small, still without feathers other than down.

We took it to the wildlife hospital that the Forest Preserve District maintains at Willowbrook Forest Preserve. They found the owlet covered with fly eggs but otherwise in good shape. Untended baby animals on the ground usually are doomed, and flies whose own young develop in decaying carcasses are quick to take advantage of a potential food source.

A few days later, after there had been time enough for Willowbrook’s animal care staff to be certain the baby was free of maggots, plans were made to return the baby to the nest. Rose Augustine, Willowbrook’s Wildlife Specialist (responsible for managing animal care and making decisions about return of rehabilitated animals to the wild), brought the bird. Mike Wiseman, Grounds Maintenance Foreman and experienced owl returner, brought his climbing equipment.

As Mike made his climb, the mother owl peered over the edge of the nest.

She flushed when he was just a short distance below. The rest of us watched out, in case she was one of the few individuals that will attack a person at their nest. Mike found a second baby in the nest and lowered it in a bucket. Rose sent up a wooden platform specially built to provide a solid foundation for a great horned owl nest. Mike set the platform in place, nailed it to the tree, and returned the nest which he temporarily had set off to the side. In the nest was a cottontail rabbit carcass, the baby owls’ meal. Last, the owlets were returned to the nest.

Mike holds one of the babies to give us a final view.

Rose and Mike headed off to return another great horned owl nestling to its home in Bolingbrook. Since that day the parent owls have continued to care for their young, but they have been understandably nervous about the uninvited home invasion and makeover. Also, the growing young no longer need to be brooded full time.

Mother owl on the remodeled nest.

As this story has shown, a number of people were involved in the rescue and restoration of this owlet. If this nest is successful, the fledged youngsters will be the first these parents have produced in 4 years. The difficulty of raising young owls is why great horneds live as long as they do. And here is the part you can play. If you know of a nest location, do the birds the courtesy of watching from a distance. If you find a baby that needs rescuing, call Willowbrook before touching it to get the best advice. Their number is 630-942-6200. (Note: this was cross-posted as a Nature Note in the Observe Your Preserve website).

Old Mystery Solved

by Carl Strang

Today’s story brings back a number of points I have tried to make over the years. For instance, there’s the idea that when one is engaged in natural history inquiries, there always are innumerable unanswered questions cooking away in memory. Sooner or later, opportunities come to answer some of them. Back in 2006, on the first day of the Roger Raccoon Club camp at Willowbrook Forest Preserve, some of the kids noticed an impressive insect.

It was perched on one of the outer roof beams of the picnic shelter.

Everyone checked it out.

It was a fly, most of an inch long. I suspect the underlying question in most kids’ minds was, will it sting or bite me?

The appropriate response to model in this situation is not fear, but interest and curiosity. Fortunately my response was interest and curiosity, so no problem. I took photos (making a record from different angles, yet another point I like to make), and noted aloud that it did not have a biting fly’s beak.

I thought it might be one of the bee flies, and that there might be some connection between it and the hole in the wood just above it, from which something appeared to be protruding.

My limited references at the time were no help. I kept the photos, and there they sat until last week. In the most recent edition of American Entomologist magazine there was a series of articles on citizen science, and one of them described an on-line publication, the Canadian Journal of Arthropod Identification. I checked it out, and found that one of its papers was a clearly illustrated key to Canadian bee flies. I remembered my photos from 2006, and was pleased to find that it didn’t take long to identify the fly. It was Xenox tigrinus, and when I plugged that name into the BugGuide website, I learned that this fly is a parasite of carpenter bees. So, not only did I get the identification, but I made the connection to the hole in the wood. The protruding object apparently was the fly’s pupal case.

Here are the reference and the link: Kits, Joel H., Stephen A. Marshall, and Neal L. Evenhuis. 2008. The Bee Flies (Diptera: Bombyliidae) of Ontario, with a Key to the Species of Eastern Canada. Canadian Journal of Arthropod Identification. doi: 10.3752/cjai.2008.06 (or: http://www.biology.ualberta.ca/bsc/ejournal/kme_06/kme_06.html ).

Recent Butterflies

by Carl Strang

Earlier I mentioned that one winner in the winter survival sweepstakes appears to have been the spring azure. Another butterfly that apparently benefits from mild winters is the red admiral, and I have been seeing enough of these already at Mayslake Forest Preserve to regard them as another beneficiary in 2012.

Sometimes the red admiral can be seen at a flower or on territory, but often all you get is a flash of orange on an otherwise dark wing as the medium-sized butterfly flits past.

It’s too soon to tell with other butterflies. Last week I got the opportunity to photograph both genders of the wild indigo dusky wing, but they are the only two individuals I have seen to date.

The female of this species is somewhat brighter and lighter.

These skippers indeed often hang around Mayslake’s wild indigo plants, but their population reportedly has increased in recent decades as their larval diet has broadened to include other legumes.

The darker male wild indigo dusky wing is different enough that one easily could believe it belongs to a different species.

It seems I have been counting a few more black swallowtails than usual, as well, but again I need to see more before I will think they had greater than usual survivorship.

Garter Snake Gallery

by Carl Strang

In my 3+ years at Mayslake Forest Preserve I have not found many snakes. Others have seen brown snakes, and I would not be surprised if there are a few fox snakes, but the ones I have seen so far all have been Chicago garter snakes. Last week I photographed the second that has given me more than the flash of a lengthy body disappearing into the grass.

The Chicago garter snake is a subspecies of the eastern garter snake. It is distinguished by black spots or bars that interrupt the side stripes near the head.

Comparing it to photos of the first snake, from the fall of 2010, I see clear differences in the pattern of the side spots and other colors.

Apart from the details of spots, the overall impression was that the 2010 snake was paler than the 2012 one.

Most of the garter snakes I have seen early or late in the season, at Mayslake or elsewhere, have been near marshes, leaving me wondering if they tend to hibernate in such areas in DuPage County. In time, as I build a gallery of garter snake photos, I may be able to get a sense of how many of them are on the preserve.

A Dancing Crane Fly

by Carl Strang

A rich diversity of healthy wild lands means that no matter how old one may get, there always will be something new to see. Last week I watched the oviposition dance of a female crane fly.

She kept her 6 long, spindly legs firmly planted in a wide stance as she bounced up and down, bending her abdomen in different ways and touching its tip to the wet mud.

It is my understanding that crane fly taxonomy is hideous, and so I did not try to identify her.

The wings had a beautiful pattern of white, brown and transparent areas.

I assumed that this was oviposition. I didn’t see any eggs. The location was close to the edge of the stream corridor marsh at Mayslake Forest Preserve, which has benefited greatly from the efforts of Mayslake’s volunteer restoration team. Such bouncing against mud just above the water line is reminiscent of obvious egg-laying by autumn meadowhawk (dragonfly) tandem pairs in the fall. This egg placement takes advantage of later spring rains that will lift the water level to inundate that bit of mud.

She was bouncing away when I first saw her, and continuing after I left. If each bounce deposited an egg, there were dozens left in just a square inch or so.

This rewarding observation was a reminder that it’s important to look up, down, all around and in all scales of magnitude if one is to experience the fullness of a wild place and its diverse life.

More Early Plants

by Carl Strang

The weather has become more seasonable of late, but plants continue to respond to the early warming of the soil. Last week brought the first winter cress flowers of the season.

The April 7 flowering date compares to 29 April last year, 13 April in 2010 and 27 April in 2009.

Oaks have broken their buds and are on the verge of flowering, as well.

White oaks usually are relatively late to open their leaves compared to other trees.

I would like to think that this will impede development of gypsy moth caterpillars. Those invasive insects hatch from egg masses which mostly are well above the ground, and it would be nice if that removal from the warm soil delayed their appearance until after the oak leaves have established some chemical protection. More likely, though, is that the caterpillars will be equally early and there will be no advantage to the trees. The coincidental timing of oak bud break and gypsy moth egg hatch is what makes oaks as a group more susceptible to defoliation by the caterpillars.

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