Palm Warbler Species Dossier

by Carl Strang

Spring emphatically is here. Seasonal milestones are being passed earlier than usual this year. Migrant birds have been coming in, so far mainly the ones that winter in the southern U.S. Migrants that wintered in the tropics are not expected to appear much before they usually do, but among the first will be the palm warbler. Therefore it’s appropriate to conclude this winter’s series of species dossiers with that songbird.

Warbler, Palm

Palm warbler

This small warbler is a frequently observed migrant, both spring and fall, wherever I have lived in Indiana, Pennsylvania, and northeast Illinois. Usually they travel in small groups (2-6). Commonly they feed on the ground, but also forage in tree canopies. They are readily recognized by their distinctive tail-wagging behavior.

26AP87. North Blackwell Forest Preserve. The song can be rendered “witch-witch-witch-witch-witch-chyer-chyer-chyer-…chee.” Very rapid and chattering. An individual observed foraging alone 3-15 feet up in saplings with leaves beginning to open. It spent most of the time perched, turning its head to look every direction, staying at a given perch 3-10 seconds. Prey were obtained mostly through hover-gleaning, with sallies mostly of 2-5 feet out from watch perches. It sang every 10-20 seconds. It also probed into leaf clusters beside its perch once in a while, but more with a drinking motion.

29AP88. Pratts Wayne Forest Preserve. A palm warbler was flycatching in a leafless tree. It also searched, with 1-4-inch hops at 1-3-second intervals, in brush near the ground. Its song was a series of “jerv-jerv-jerv” notes, slightly juicy or buzzy, 4-6 quick syllables.

30AP89. McDowell Grove Forest Preserve. Some palm warblers were performing mid-air sallies (perches achieved at 5-10 second intervals between flights, and the birds did not return after making a grab but continued to a branch straight ahead, after flights of 7-15 feet). Others were foraging on the ground, hopping on paved or graveled areas. One sang a loud song: “Der-see’, der-see’, …” fast, the first syllable barely there, much emphasis on second syllable, ~10 syllables per song, many seconds between songs.

8MY89. Last bird of migration noted.

1OC89. Hidden Lake Forest Preserve. Palm warblers were in woods at a field edge, with white-throated sparrows.

25AP99. Palm warblers were at the Morton Arboretum in an area with pine warblers and chipping sparrows.

3MY99. A palm warbler was foraging 10-15 feet up in box elder at Willowbrook, the first of the year observed there.

5MY99. McDowell Forest Preserve, afternoon. There was little bird activity, generally, except for lots of palm warblers (and yellow-rumped warblers) feeding.

15MY99. A late bird seen at Red Oak Nature Center.

1MY00. A flock of palm warblers fed on the ground in the center of the cleared prairie at Willowbrook. Some also moved into scattered trees in the prairie area.

24SE00. A couple palm warblers were at the Sparrow Hedge, Fermilab.

20OC01. Blackwell, McKee Marsh. A palm warbler gave call notes similar to those of a yellow-rump.

12OC02. Several palm warblers were at Fermilab in old field areas.

28AP08. Fullersburg. A palm warbler was giving a call note similar to the distinctive one of the yellow-rump, though possibly higher in pitch.

Lessons from Travels: Pennsylvania Salamanders

During the five years I lived in south central Pennsylvania, my research focused on wood turtles and eastern box turtles, as I mentioned earlier. But I also was intrigued by the diversity of salamanders in the Appalachians, and had I remained, sooner or later I would have worked with them as well. Here in northeast Illinois our salamander fauna is limited to the mudpuppy, a newt, 3 mole salamanders, and perhaps a couple others, but most of these are rare and some were limited to the wooded wetland areas close to Lake Michigan. On my study area at the Reineman Sanctuary in Pennsylvania, salamanders were diverse (14 species live in that area, though I did not encounter all of them) and some occurred in large numbers. By far the most abundant was the dusky salamander.

Dusky salamanders lived in huge numbers in the little rocky streams.

In fact, the streams were where I found most species. Unfortunately I didn’t photograph many of them. At least 95% of individuals there were the duskies. Occasionally I found others.

Two-lined salamander, another stream species.

There also were salamanders on land. I remember encountering tiger, spotted, and a magnificent marbled salamander, all in the mole salamander group. There also was the red salamander.

Red salamanders never were far from water.

The Appalachians provide more consistent moisture than we have in the northeast Illinois prairie region. The soil is shallower, so the streams are packed with stony refuges, and in the mountains the streams are shorter and their waters purer. These factors all come to mind when considering the difference in salamander diversity of the two regions.

New Trap Critters

by Carl Strang

One way of assessing the biodiversity of an area is by the rate at which new species are added to the area’s list with sampling effort. There are ways of doing this quantitatively, but in my amphibian trap sampling of the stream corridor marsh at Mayslake Forest Preserve I am (so far) just getting a qualitative sense of what is there. My sampling has been limited to just a few tens of trap-days last season and this. Still, the traps continue to produce new finds, including three species last week.

It must have taken some effort for this 3-inch bullfrog to squeeze into the trap.

Two leopard frogs were in another trap. I didn’t take a photo. I also caught a few water bugs.

They all have been this size (less than an inch long), and they have the shape of giant water bugs.

One of them proved to be an adult male, with eggs attached to his back.

The males carry the eggs, keeping them clean and oxygenated.

There are 3 genera of giant water bugs in the eastern U.S. The ones I had heard of, the ones famous for attacking tadpoles, fishes and other vertebrates, have a significantly larger body size at maturity. The second genus, with only one species in the eastern U.S., was easily ruled out. That left genus Belostoma. I was not able to determine the species from the photos.

I keep records of all individuals caught in the traps. At some point I will be able to chart number of species added against number of individuals caught, and number of species added against trap-days, to get a more quantitative sense of the marsh’s biodiversity. As long as I am catching new species this frequently, though, it makes sense to wait.

Bloomin’ Early

by Carl Strang

With a string of record highs, and temperatures remaining warm overnight, the degree-days have accumulated to the point where lots of plants are flowering already. Usually I don’t have much to say about phenology until the end of April, but this year it is clear that many species will be showing their earliest flowers of the past four years at Mayslake Forest Preserve by a significant amount. Today I’ll share a few of these early bloomers.

In previous years I hadn’t recorded the first flowering date for weeping willows, but they were going full blast last week.

Another woody plant that opened flowers last week was the wild plum.

These flowers have superior ovaries, though it isn’t obvious until you dissect one.

Spring beauties are expected to be among the first native wildflowers to bloom, but not in March!

Already by March 10 they were abundant on the savanna hillside below the former friary.

Swamp buttercups also were earlier than in past years.

I am having to brush off my identification skills earlier than expected.

Today’s final species is a new one for the preserve list, a product of my altering survey routes from past routines.

The hairy bitter cress is a weedy plant, nothing spectacular, but any new species is stimulating.

Next week I’ll provide the statistics quantifying this year’s difference from the previous three.

Literature Review: Cenozoic Prior to Pleistocene

by Carl Strang

The Cenozoic Era extends from the catastrophe that ended the Mesozoic Era up to the present day. Today’s literature review includes some research published last year pertaining to the bulk of the Cenozoic. Next week I will finish with some Pleistocene studies.

Leaf mine

Winkler, Isaac S., Conrad C. Labandeira, Torsten Wappler, and Peter Wilf. 2010. Distinguishing Agromyzidae (Diptera) leaf mines in the fossil record: new taxa from the Paleogene of North America and Germany and their evolutionary implications. J. Paleont. 84:935-954. Leaf-mining flies’ “mines often can be distinguished from those of other insects by the presence of an intermittent, fluidized frass trail that may alternate between the sides of the mine.” These researchers found an example of this pattern in an early Paleocene fossil sycamore leaf, Platanus raynoldsii, from Montana. They also see in those leaves “associated stereotypical marks identical to damage caused by feeding punctures of extant adult female Agromyzidae prior to oviposition.” This is the earliest fossil agromyzid (the family of these leaf-mining flies), named Phytomyzites biliapchaensis. Sycamores today do not have leaf mining agromyzids. The researchers speculate that this was “an evolutionary, possibly opportunistic colonization in the midst of the ecological chaos following the end-Cretaceous event in North America.”

Antoine, P.-O., et al. Middle Eocene rodents from Peruvian Amazonia reveal the pattern and timing of caviomorph origins and biogeography. Proceedings of the Royal Society B: Biological Sciences, 2011; DOI: 10.1098/rspb.2011.1732     Caviomorph rodents are the group that today characterizes the South American fauna and includes such species as guinea pigs and capybaras. These researchers found fossils of 3 species from 40 million years ago, much older than the previously known earliest South American rodents. The fossils indicate that the origin of that continent’s rodents was a rafting colonization from Africa.

Clarke, Julia A., et al. 2010. Fossil evidence for evolution of the shape and color of penguin feathers. Science 330:954-7. They describe a fossil giant penguin (Inkayacu paracasensis) from Peru, 36 million years ago in the late Eocene Epoch. The penguin’s primary wing feathers were difficult to distinguish from the coverts. Body contour feather shafts were broad like those of today’s penguins, and of similar proportionate length. Melanosomes suggest the colors were gray and reddish-brown.

Mihlbachler, Matthew C., et al. 2011. Dietary change and evolution of horses in North America. Science 331:1178-1181. They measured crown height and microwear of horse molars from the early Eocene on. There was considerable variation in the amount of wear for a given crown height, but in general wear increased with height. They interpret this to mean that selective pressure for increasing crown height generally was weak. There were times, however, when wear was greater, “including the early Miocene shortly before the first appearance of Equinae, the horse subfamily in which high-crowned dentitions evolved.” This supports the connection between the spread of grasslands in the Miocene (grasses are a relatively abrasive food) and the evolution of high-crowned teeth.

Cycad, King’s Canyon, central Australia.

Nagalingum, N.S., et al. 2011. Recent synchronous radiation of a living fossil. Science 334:796-799. They looked at cycad relationships based on molecular comparisons with fossil calibrations. The earlier assumption was that today’s 300 species are a holdover that survived the large drop in diversity in the Jurassic and Cretaceous that occurred with the rise in flowering plants, and thus are “living fossils.” Surprisingly this research group found that today’s species are the result of a diversification that began in the late Miocene, so that they “are not much older than ~12 million years.”

Marsh Invertebrates

by Carl Strang

They are called “amphibian traps,” but the little cage-like contraptions I have been running at Mayslake Forest Preserve’s stream corridor marsh have revealed more about the wetland’s invertebrates than its amphibians, though last week’s tiger salamander was a major coup. The salamander was not alone in its trap, as there also was one of the predaceous diving beetles, Dytiscus verticalis, one of only two I’ve caught so far this year. That low number makes me wonder if predators such as the bufflehead pair and the hooded mergansers that frequented the marsh last year might have made inroads on the Dytiscus population. On the other hand, a few representatives of a new insect turned up in the traps last week. At first I thought they were water boatmen, as they preferred to sit on their bellies in the trap.

The pale backs made me suspicious, however, as this seemed likely to be the countershading one would expect in a backswimmer.

Sure enough, when placed in the water, the half-inch-long true bug flipped over.

The dark underside blends with the marsh bottom, while the pale back is better camo against the sky.

As best I can tell from the BugGuide website, these belong to the common species Notonecta undulata. I also found some amphipods.

Also known as scuds or sideswimmers, these tiny invertebrates are not identifiable to species from photos. There seem to be a lot of them, though, in the marsh.

A final, more familiar invertebrate in the traps has been the white river crayfish.

Two of the red-hued crustaceans turned up last Friday.

They are one of Mayslake’s two known crayfish species. I found a tragic example of the other while leaving the marsh on Tuesday.

It was a large, dead grassland crayfish.

Grassland crayfish live in tunnels they dig on land, away from open water, though the tunnels go deep enough to reach the water table. Sometimes these odd crustaceans climb up on land to wander on warm, humid nights. Now is the time of year when mothers leave their tunnels to carry their young to water and release them. The young grow to the point where they are big enough and strong enough to go out on land and dig their own tunnels. After letting the babies go the mothers remain in the water for some undetermined time, and then return to their homes. The dead crayfish was pointed toward the marsh. I turned her over.

Sure enough, the ground beneath her abdomen was littered with little dead crayfish. Others still were stuck to the mother.

She nearly had made it.

The dead crayfish is at the center of the bottom edge of this photo. She is only 15 feet from the water’s edge.

I’m inclined to attribute this tragedy to the unseasonably warm, dry weather we have enjoyed in recent days. In most years the mother crayfish can come out in March, day or night, with no danger of dehydration. Not so in this case.

False Map Turtle

by Carl Strang

The addition of new species to a site list always is welcome in preserve monitoring. When that organism belongs to a group that is not well represented, the occasion is even more noteworthy. The reptile list for Mayslake Forest Preserve was very short, at two snakes and two turtles, before last week. Therefore I felt some delight when I spotted an unusual profile among the turtles basking in the spring sun at May’s Lake.

It was backlit, but the little knobs on the center of the shell distinguished it from the midland painted turtles that are the usual visual fare.

Fortunately I could see enough to identify the new turtle.

Those knobs, the brown back, and the relatively small head make this a false map turtle.

Personally this was a special treat, as I have loved turtles from childhood on. I suspect that there are more reptiles (though probably not more amphibians) to be found on the preserve, but with the tiger salamander and the false map turtle both added last week, the picture is improving.

Chorus Frogs in Hiding

by Carl Strang

This year the early songs of western chorus frogs at Mayslake Forest Preserve are coming mainly from locations inland from the water’s edge at the stream corridor marsh, their biggest breeding area. I don’t know if this represents a change in behavior, or whether I simply had failed to notice it in the past. Most of the little guys seem to be singing within clumps of brown grasses and sedges, usually within a few feet of the water’s edge. Last week I was able to get a partial peek at one which had chosen a slightly more exposed spot.

In the exact center of this photo is a tiny puddle of water, about 4 inches across, between the two sticks. Whenever the frog sang, the water in the puddle vibrated, giving him away.

I was able to get close enough to see his exact location under the smaller stick.

Can you see the little highlight in the stick’s shadow?

Unfortunately for me, the bigger stick blocked my view and prevented me from holding the camera at a low enough angle to see more than the tiniest part of the frog.

This expanded part of the previous photo shows the yellow edge of the frog’s bag-like expanded throat.

After a few days last week when dozens of frogs sang, nearly all have gone quiet. They barely had started, and I can’t believe they have finished already. I find myself attributing the many bizarre things I am observing on the preserve to the abnormally warm, dry weather. The main pool of the stream corridor marsh has shrunk slightly, and this week the tiny puddle shown in the photos is gone. Chorus frogs breed in temporary pools. Their tadpoles develop fast, but need to have those pools last a few weeks. The marsh will be there for them, but they don’t know that and I suspect that some cue is telling them to wait. If I am right, a period of rain and/or cooler temperatures should get them going again.

Salamander Surprise

by Carl Strang

Last week the herps (reptiles and amphibians) dominated the natural history news at Mayslake Forest Preserve. The biggest single item was an addition to the preserve species list that I frankly did not expect.

A tiger salamander!

While it is true that tiger salamanders are widespread if not abundant in DuPage County (the Observe Your Preserve website gives 15 or so known locations), I had thought that Mayslake’s agricultural history might have done them all in there, and we had no previous site record.

I was unprepared, I have to admit, but yet again the camera proved to be a valuable research tool.

For instance, I was able to determine the gender as male from the large swellings behind the hind legs. I’m inclined to name him Mickey thanks to the appropriately shaped yellow spot on the side of the tail toward the tip (rotate the big spot a quarter turn clockwise).

In my years at Fullersburg Woods I learned that individual differences in spot pattern can be used to distinguish fawns as long as those last. I am hopeful that the same is true for tiger salamanders.

Accordingly, I took a number of photos from different angles.

With the continuing improvement in the size and quality of the stream corridor marsh resulting from the hard work of Mayslake’s restoration volunteers, there is the potential for a big population increase in tiger salamanders, to go along with those of western chorus frogs and American toads.

Literature Review: Mesozoic Life Style

by Carl Strang

Today I close out my notes on last year’s published research pertaining to the Mesozoic Era. The following papers looked at the long-standing question of dinosaur metabolism, investigated the extent to which there were nocturnal dinosaurs, and made revelations regarding the reproduction and life history strategy of some non-dinosaur reptiles.

Were dinosaurs warm-blooded? Field Museum of Natural History exhibit.

Eagle, Robert A., et al. 2011. Dinosaur body temperatures determined from isotopic (13C-18O) ordering in fossil biominerals. Science 333:443-445. They looked at the isotopes of those elements in sauropod teeth, and found that these point to body temperatures of 36-38°C, similar to most modern mammals. Some models have indicated that their body mass would have resulted in even higher temperatures, and the authors suggest that the sauropods had heat-release mechanisms such as air-sac systems and circulatory networks that took advantage of the large surface-to-volume ratios in neck and tail (sauropods were the diverse herbivores that walked on 4 legs and had very long necks and tails).

Amiot, R., et al. Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1011369108     They looked at oxygen isotopes in bones and teeth of fossils in the Chinese Jehol fauna, and found that the climate there probably was temperate, with winters severe enough to force scaled reptiles (turtles, crocodiles) into hibernation and giving the advantage to dinosaurs that were feathered. Thus the famous high incidence of feathered dinosaurs in that area and time was not simply the result of better preservation of fossil detail, but a result of climatic conditions.

R. S. Seymour, S. L. Smith, C. R. White, D. M. Henderson, D. Schwarz-Wings. Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs. Proceedings of the Royal Society B: Biological Sciences, 2011; DOI: 10.1098/rspb.2011.0968     They looked at nutrient foramen diameters within bones of mammals, reptiles and dinosaurs of a wide range of body sizes. They found that diameter increases with metabolic rate in living species, and dinosaur foramen diameters are proportionately even larger than those of mammals, supporting high metabolic rate in dinosaurs.

Schmitz, Lars, and Ryosuke Motani. 2011. Nocturnality in dinosaurs inferred from scleral ring and orbit morphology. Science 332:705-708. They were able to connect archosaur species to nocturnal or diurnal habit based on eye-ring and skull structure. In general, like today’s amniotes, pterosaurs were mainly diurnal, terrestrial predators at least partly nocturnal, and large herbivores active day and night. Archosaurs are a large reptile group containing dinosaurs, pterosaurs and others.

Pterosaur skeleton, Field Museum of Natural History exhibit.

Junchang Lü, David M. Unwin, D. Charles Deeming, Xingsheng Jin, Yongqing Liu, Qiang Ji. 2011. An Egg-Adult Association, Gender, and Reproduction in Pterosaurs. Science 331: 321-324 DOI: 10.1126/science.1197323     A newly described fossil from China’s Liaoning Formation is a female Darwinopterus pterosaur with an egg still inside. There is enough detail in the fossil to show that the animal had wide hips and lacked a crest. This is being cautiously generalized as an indication that in other pterosaur species, hip width and crest presence or absence may allow identification of fossils to gender, and allow fossils of different genders that had been regarded as separate species to be combined under the same name. The egg had a parchment-like shell, and its size in comparison to the adult is like those of modern reptiles. The shell points to burial with water uptake after laying. “This evidence for low parental investment contradicts the widespread assumption that reproduction in pterosaurs was like that of birds and shows that it was essentially like that of reptiles.”

O’Keefe, F.R., and L.M. Chiappe. 2011. Viviparity and K-selected life history in a Mesozoic marine plesiosaur (Reptilia, Sauropterygia). Science 333:870-873. They describe a fossil that for the first time shows a fetus within an adult. The fetus is single and large, demonstrating birth rather than egg-laying, and single or small brood number, separating it from other marine reptiles but resembling marine mammals. The authors speculate that this may imply “sociality and maternal care.” Plesiosaurs were the large aquatic reptiles with long necks, and legs replaced by 4 large flippers.

« Older entries

%d bloggers like this: