30 November 2008

Beaver dam at Hoyles Mill

Towards the end of our field trip at Hoyles Mill Conservation Park on Friday, Tim Pearce and I were following a creek that, according to the map, intersected with the road that was to take us back to the car. Along the way we started seeing trees that had been felled by beavers. Soon, we were amidst an arboreal carnage.


Naturally, the scenery around us lead to freewheeling questions. What would happen if there were as many beavers on earth as there are people? Well, there couldn't possibly be 6 billion beavers, because there wouldn't be enough trees for all of them. Do beavers have predators? They must, because they've evolved a warning behavior—tail slapping on the water. Is the lack of beaver predators in suburban parks leading to unchecked population growth and consequently, excessive tree destruction? We couldn't answer that one.

Better not stand too close to this one.

Then we noticed that the flow rate of the creek had slowed down considerably: we were probably approaching a dam. Sure enough, first we came to a flooded area and had to take a detour to avoid getting wet. And finally, the beaver dam came into view.


We estimated the length of the dam to be about 20 m and the height about 1.5 m.


The beavers themselves and their lodge were nowhere to be seen. I will be visiting that area throughout the winter. I will try to post updates here.

28 November 2008

The day after Thanksgiving field trip, or what's up with the little yellow flags?

Every year after Thanksgiving Tim Pearce and I try to go on a field trip together to collect land snails. The highlight of the 2006 trip in Virginia was the discovery of the European snail Cecilioides acicula. We couldn't get together last year, but we were able to return to our tradition today with a trip to Hoyles Mill Conservation Park in Montgomery County, Maryland. The last time I was there was back in May.


The best spot during our 4-hour trip was this dead tree. We found 5 live, but dormant Anguispira fergusoni buried in the damp and soft soil among the roots. Each snail's body was about 1/4 whorl behind its aperture.


I placed the snails back in the soil, covered them up and marked their locations with little yellow flags. I had the flags with me, because I had been hoping to do a study like this. The idea is to see if the snails become active during the rest of the winter and change their locations. Hopefully, my handling of them today did not wake them up.

2 flagged Anguispira fergusoni (arrows) before they were reburied.

This, of course, means that I will be going back there to check up on them. I did a similar study with a Haplotrema concavum last winter. That story is here.

Follow up posts are here and here.

27 November 2008

Random books for Thanksgiving day

Engrossing reading to settle down your stomach after a heavy Thanksgiving meal.

We have so far made good use of our Thanksgiving day by cleaning out and rearranging the furniture in a heavily used room that was on its way to demonstrate the validity of the 2nd law of thermodynamics. Accordingly, it required the spending of quite a bit of energy to lower the entropy to a more acceptable level. The ordeal included the emptying and repositioning of 2 tall bookcases followed by the reshelving of the books.

During the process 3 books I had read a while back attracted my attention.

The Best of H. P. Lovecraft: Bloodcurdling Tales of Horror and the Macabre (1982) is left from the days, more than 15 years ago, when I was into Lovecraft. I read most of his stories and also Sprague de Camp's biography of him. Then I lost interest. But I still have his books and may one day try to catch up with the unspeakable Cthulhu again if I can ever figure out how to pronounce that word.

Niko Tinbergen's Curious Naturalists (1958) is an enjoyable little book chronicling the great biologist's nature studies. My favorite quote from the book (actually from the preface):
...some fields of biology seem sometimes to lose touch with biology's original object—living things in their natural surroundings.
Great Scientific Experiments by Ron Harré (1981) is about "20 experiments that changed our view of the world". I was never too impressed with that book; perhaps, because the writing wasn't very good. But now that my interest in the history of sciences has been rekindled, I may need to take another look at it.

26 November 2008

Its not that hard to use apostrophe's correctly

According to the result's of a recent survey in the UK, nearly half of that countrys adult's were unable to use apostrophes' properly. Lets be more careful with our apostrophe's from now on. Its' really not that hard if youre paying attention to where its supposed to go.

Its about time we showed those Briton's whos better with they're apostrophe's.

25 November 2008

History of science at the used book store

I have a minor interest in how scientific discoveries are made and another minor interest in the history of sciences, especially biology. The 2 interests are necessarily connected, for if one knows the history of a particular science, then it is easier to understand how the major discoveries in that field were made and vice versa.

I was, therefore, delighted last weekend when I visited my usual used bookstore and found 4 relevant books.


They were J.D. Bernal's The Scientific and Industrial Revolutions (1965), The Evolution of Biology by M. J. Sirks & C. Zirkle (1964), Thomas S. Kuhn's The Structure of Scientific Revolutions (1970) and Willy Ley's Dawn of Zoology (1968).

The only one I had heard of before was Kuhn's book. But the most expensive among them being merely for $3, it would have been a shame to leave anyone behind and so I bought them all. Now I have to find time to go thru them, perhaps by skim reading.

Whatever interesting and useful ideas and facts I can distill out of the books are likely to be subjects of future posts.

24 November 2008

Hit them with your best shots

About 10 days ago, Bruce Berman from Boston, a regular reader of this blog, sent an inquiry about the impact of blogging on the evolution versus creation debate. Apparently he is writing a paper on this subject. Only yesterday was I able to get back to him. Here is my response, slightly revised today.

I think the greatest impact the Internet (not just blogging) has had on the freedom of expression is that everyone who has Internet access has a chance to publish their thoughts, at least in the U.S., where the government does not and can not censor publications. The downside of this is that the crackpots, the deceivers, the zealots, the fundamentalists, etc., get their webpages too. But that's the price of freedom; it's either all or none.

The point I am trying to make is that the evolutionists and the rationalists aren't the only ones who have taken advantage of the Internet, but so have the creationists and the religionists.

But I think the significance of the Internet is that everyone is more or less on an equal footing. And perhaps more importantly, no crackpot is immune from criticism. If one is brave (or foolish) enough to reveal one's ideas for all to read, one should be prepared to accept the consequences and not complain when and if the failings of each are exposed by others who also write on the Web.

I will paraphrase one of Bruce’s sentences from his e-mail: The web has finally given everyone with defensible arguments a powerful channel to reach a wider audience. It's up to us to create the best defenses to support our positions and to attack with the most effective offenses to crumble our opponents' lines.

23 November 2008

Cannibalistic slugs

I have written about slugs eating earthworms, apples, dog feces and cat food. Today I am going to write about slugs eating slugs.

About a week ago one night after a rain when it was much warmer than it is now, I went out to my yard to check up on the resident slugs and snails. By the time I realized there were slugs were all over the place, especially on the dying leaves of the lilies, I had inadvertently stepped on one hapless Deroceras reticulatum. I went inside to get my camera and when I came back out about 15 minutes later, another Deroceras reticulatum had discovered its squished kin and was already devouring it.

Lucky is the slug who comes upon an unlucky slug. Note the isopod on the left that was consuming its share of the dinner.

However, my activities must have been too intrusive, for the slug left soon after I started taking pictures. I followed suit and went inside.

More than an hour later, I went back out again. This time yet another Deroceras reticulatum was engaged in cannibalism (I know it was a different individual, because its mantle patterns are different than those of the 1st one). And a millipede had taken the isopod's place.


Deroceras reticulatum was originally introduced from Europe and is now widespread in the U.S. Its omnivorous and catholic food preferences must certainly have contributed to the successful invasion it has carried out.

21 November 2008

In Butterboy we trust

Pearls Before Swine by Stephan Pastis.

He is probably as good as any other god.

Cats of Istanbul - Part 2

The British explorer, archeologist Charles Fellows encountered nomadic Turkish tribes on many occasions while traveling in southwest Turkey in 1840. In his book Travels and Researches in Asia Minor, Fellows described a typical procession of them:

An old man, and generally his wife, head the clan, which consists of several generations...His son, the master of the flocks, follows with his wife; she is often seated on a horse, with a child in her arms...Asses are allotted to the younger children, who are placed amidst the domestic stores, and never without a pet cat in their arms...
The association of the Anatolians with cats probably goes back many centuries and is still an ongoing affair as revealed by the abundance of cats in Turkey.


I saw this man, sitting amidst the prayer beads and the flags he was selling and the cats he was keeping, in the Sahaflar district of Istanbul. After giving me permission to take photographs, he started complaining of the abuse his cats would sometimes get from unappreciative strangers. The sleepy felines looked good, though.


Part 1 was here.

More to come.

20 November 2008

It’s dew, dude!

Zebrina detrita crawling on dew covered grass. Photographed last October near Kastamonu, Turkey.

Ever since I witnessed some land snails crawling around on dew covered plants one early and cold morning last October while I was in Turkey, I have gotten interested in the activities of snails and slugs at low temperatures.

I have also been reading about the fundamentals of dew formation. Nothing profound though, only the very basic stuff.

Dew is liquid water that condenses out of the air, usually at night, as a result of a drop in temperature. How does dew form?

Let’s see if I got it right.

It's all thermodynamics and the thermodynamicists usually work with sealed systems constant at some property or other. So, consider a sealed vessel containing some water at a constant temperature, T1. Some of the water molecules in the liquid phase will evaporate into the vapor phase, while some of those in the vapor phase will return to the liquid. After a while, an equilibrium will be attained and after that point, the amount of water in the vapor phase (and in the liquid phase) will remain constant. The vapor phase will be saturated with water vapor. If we increase the temperature to T2, however, additional water will evaporate and at the new equilibrium point, there will be more water in the vapor phase than there was at T1.

Now, what will happen if we reverse the process and lower the temperature back to T1? Some of the water in the vapor phase will have to condense back into the liquid phase until the amount of water in the vapor phase returns to its equilibrium value at T1. As we see in the next diagram, the saturation amount of water in the vapor phase changes continuously as a function of temperature. Therefore, if the temperature of a system saturated with water vapor is lowered even just a tiny bit, some water will condense out.

The red curve shows the variation with temperature of the saturation (equilibrium) vapor pressure of water. Ignore the blue curve. Fig. 3.9 from Atmospheric Science: An Introductory Survey by John Michael Wallace & Peter Victor Hobbs, Academic Press, 2006 (yellow and brown lines mine).

What if there isn't enough water in the vessel to saturate the vapor phase? In other words, if we put a very small amount of water into our vessel and the vapor phase is not saturated even after all of the water evaporates, will some of it still condense out when the temperature is lowered? Yes, it will if the temperature reaches a low enough value (less than T1) at which the vapor phase will be saturated with water.

This is basically how dew forms. If the air is saturated with water, in other words, when the relative humidity is 100%, the air is said to be at its dew point temperature (Td), because dew will be forming. If the air is not saturated, then the air temperature needs to fall down until the air becomes saturated with water vapor so that dew can start to form. That particular temperature will be the dew point temperature.

Let's look at the diagram again. Suppose the air temperature is 20 °C. The saturation pressure of water vapor at that temperature, marked by the yellow line, is ~20 hPa (hectopascals). But suppose that on a particular dry evening the vapor pressure happened to be ~10 hPa. That would make the relative humidity (10/20)x100=50%, which is the saturation vapor pressure at ~10 °C (brown line). Therefore, Td is 10 °C and dew will form if the air temperature drops down to 10 °C during the night.

So the dew point temperature is determined by 2 things: the temperature and the relative humidity.

There is a simple formula that gives the approximate Td if the relative humidity (RH) is >50%.

Td= T-((100-RH)/5)

In our example, Td= 20-((100-50)/5)=10. There are more exact dew point calculators here and here.

What does all of this have to do with snails?

In a nut snail shell:

1. Snails need water to be active.
2. If during certain times of the year rains are infrequent, dew formation may be the only source of water available to snails.
3. If the daytime temperatures are in the range 14 to 20 °C and the relative humidity is low (~50%), then dew point temperatures will be much lower (<10 °C; see Figs. 1 & 2 in Lawrence, 2005).
4. Under such conditions, snails will be forced to be active at low temperatures.

This is exactly what I witnessed on that cold October morning.

Disappearing blog post trick

Yesterday's post seems to have vanished. I will try to repost it tonite.

19 November 2008

Get your opinion injections here

An exchange of e-mails with Deniz yesterday was concerning the relevancy of the classic The Elements of Style to our times. Strunk’s 1918 original is available here; my paperback copy is a 1979 Strunk & White edition.

One advice that sounds quite irrelevant in this age of blogging is "Do not inject opinion" (No. 17 in Chapter V of the 1979 edition). But blogging is all about injecting opinions! If you don’t like the opinions I inject into your mind, you may counter-inject your opinions by posting a comment (and if I don't like them, I'll delete them!).

Deniz wrote:

Imagine if they could see the blogosphere now!
Let me be fair, though, for the advice of Strunk & White wasn’t totally pointless. They were mostly concerned with the kind of opinions "scattered indiscriminately", those presented where none is necessary. Their example makes perfect sense:
If you have received a letter inviting you to speak at the dedication of a new cat hospital, and you hate cats, your reply, declining the invitation, does not necessarily have to cover the full range of your emotions. You must make it clear that you will not attend, but you do not have to let fly at cats.
Of course, most of what’s in Strunk & White is still good and useful. When I am trying to decide whether to use that or which, for example, I follow their advice in Chapter IV; when I am revising a manuscript, I try to omit as many needless words as possible as they recommend in section 17 of Chapter II.

Yet, I blog, therefore I inject opinions.

18 November 2008

Dead spotted salamander

An unexpected find last Sunday–I wasn't even searching for anything–was a spotted salamander (Ambystoma maculatum). It was on the street and I rode by it on my trike. I had gone several meters before it dawned on me that what I had seen was probably not a piece of stick. So I turned back for a 2nd look. This is one advantage of riding a recumbent trike: you are much closer to the ground and so are more likely to spot the interesting stuff on the roads than you would be on an ordinary bike.

The salamander was stiff and unresponsive to touch. Best of all, it wasn't yucky or smelly. So I wrapped it in a paper napkin and brought it home in my vest pocket.


If it were straight, it would be about 14 cm long, within the size range of 11.2 to 19.8 cm White & White give for the species (Amphibians and Reptiles of Delmarva by James F. White, Jr. & Amy Wendt White, 2002). It is definitely an adult. There were no external injuries that I could see. We will put down the cause of death as exposure. According to White & White, the spotted salamander is "primarily a subterranean animal". What was this individual doing on the road then?


After I took its pictures, I wanted to dissect it, primarily to examine its gut contents to see if it had eaten any snails. But I already had too many other things to do, therefore postponed the dissection for a rainy day when I am less busy. With my wife's permission, the amphibian is now in the freezer of the spare refrigerator.

17 November 2008

Slugs on the beech

The native philomycid slug Megapallifera mutabilis, abundant in the woods near my house, has a thing for beech trees. In this post I noted how one can tell that there are philomycid slugs at a location from the feeding tracks they leave on the algae-covered smooth trunks of beech trees (Fagus grandifolia).

This past weekend's weather, wet and unseasonably warm, was good for slugs. During a walk in the woods I came upon this beech, still wet from the earlier rain, with many shiny lines covering its trunk. Some of them may have been the trails left by streams of water running down to the ground, but at least those that were going sideways were definitely slug trails.


In fact, there were 2 slugs on it (arrows). The higher and the bigger one was about 4 m above the ground. To ascertain that it was what I thought it was, I brought it down with a long stick.


It was what indeed a Megapallifera mutabilis. The fall didn't harm it and after it untwisted itself, it went about its business.


It's time to pillage the Royal Society!

A message from the Royal Society Publishing group on Facebook that came on Friday announced that "The complete Royal Society journal archive, dating back to 1665, is FREE to access until 1 February 2009".

Waste no time, grab a sack, or better yet, a flash drive, head over to the Royal Society journals and start downloading.

16 November 2008

Ring-necked parakeet in Istanbul

Photo by Beste Barki.

My sister, who is spending this fall and winter in Istanbul, photographed this bird last Thursday from the window of her condo in the Ulus district of the city. I am identifying it as the ring-necked parakeet (Psittacula krameri).

These birds are native to certain parts of Africa and Pakistan, India and the neighboring areas. However, there are naturalized colonies in several European countries, including England, Greece and Turkey, that are believed to have been established by birds that escaped from captivity. The records from Istanbul go at least as far back as 1996 (example).

14 November 2008

Octopus ring


This silver octopus ring with shiny glass eyes is one of the few things, besides books, that I bought for myself in Turkey last month.

The Ortaköy district of Istanbul has a wide opening where several restaurants facing the Bosphorus are lined up. The narrow streets leading to the waterfront are always crowded with vendors selling mostly jewelry. We went there one day to have lunch and also to look for trinkets. Trying the stuff on is, of course, half of the fun.


One of those street vendors was offering many unusual rings. I was looking for a snail ring, but had to settle for another mollusk.


Watch out for those tentacles.

13 November 2008

Cold slugs

Are snails and slugs normally active only when it's warm and humid? Until recently, my answer to that question would have been a confident "Yes". But thanks to the recent data I've gathered, starting out with some chance observations on a cold morning in Turkey back in October, my current answer would be "They can also be active when it's cold and humid".

Of course, "cold" is a highly relative feeling, mostly dictated by our human sensations. What feels cold to me might be rather comfortable to a snail, if they have roughly equivalent sensations. So to avoid ambiguity, let us dispense with feelings and, instead, set 10 °C as an arbitrary boundary for "coldness". I am interested in the activities of snails and slugs below 10 °C.

Following the light rain we had last nite, I went out around 8 o'clock to check up on the local slugs.

To my surprise and delight–my favorite animals never cease to surprise and delight me–slugs were at it. A particular section of the sidewalk along a forested area was teeming with a particular species that I believe was Deroceras reticulatum.


The temperature right above the wet concrete sidewalk was about 7 °C (the upper number is the relative humidity, which was 100%).

In the nearby woods, the native philomycids were scouring the trunks of the beech trees.


At that location, where I visited slightly earlier, the air temperature was around 8 °C.

Megan Paustian and I are still arguing about the identity of the latter species. Is it Megapallifera mutabilis or Philomycus carolinianus? But that's beside the point. Last nite's observations show that slug activity doesn't cease at temperatures down to about 7 °C.

How far down the temperature needs to go before it gets too cold for the slugs to go crawling? Hopefully, we will find out.

12 November 2008

Binoculars, hourglasses, plastic babies, oh my!

Whilst visiting Istanbul's famous Grand Bazaar or the Kapalıçarşı (Covered Bazaar) as it is called in Turkish, one tends to get overwhelmed by the numbers of jewelery stores; some roads within the complex have nothing but one jewelery store after another. After a while, you begin to wonder how they can all survive.


The occasional store that offers different, and somewhat unusual, merchandise provides a relief from the endless glitter of all that is gold and silver. This particular store was one such place, where the source of glitter was mostly brass and glass.


Its display windows were crammed with old binoculars, telescopes, opera glasses, cameras, compasses and an old telephone...


an hourglass, more binoculars, cameras and even an old brass microscope...


some watches, another hourglass and a box full of something, old slides, perhaps. And among all those instruments, devices and apparatus were 2 small plastic dolls. Don't ask me.

11 November 2008

Written in stone: know thyself

While vacationing in Turkey last month, we visited Safranbolu, a town famous for its old houses. One large 19th century house, now a museum, is known as Kaymakamlar Evi, the Governors' House.

In the veranda, near the entrance, there was a small exhibit of various artifacts, old farming implements as well as several stone fragments. One of them was this piece inscribed with Greek letters. I photographed it hoping that it was an example of Karamanlica, Turkish written with Greek characters. (If you go to this page and click on the second image, in the enlarged version you can see the subject stone on the right towards the back.)


Later, I transcribed the Greek letters into Turkish characters; but the words I got were meaningless. So, a couple of days ago, I e-mailed the picture to my friend Yorgi Sangiouloglou in Athens and asked for his help.

Yorgi informed me that it wasn't Karamanlica, but Greek and translated the phrase as the ancient dictum Gnothi eafton, "know yourself" (more info)

The date underneath is 1863 Septem[ber] 30.

Before the Greco-Turkish War (1919-1922), Safranbolu was home to many Greeks. Following the defeat of the Greek forces and the Treaty of Lausanne, the Anatolian Greeks were forced to migrate to Greece never to return. This stone is a fragment of the millennia old culture that disappeared with their departure.

Where did this inscription originally stand and what was the significance of the date on it? We will probably never know.

10 November 2008

Juvenile Northern Brown Snake

I came upon this tiny snake while looking for snails under a small log near College Park, Maryland last week. The Triodopsis shell next to it was probably about 12 mm in diameter. Using that as a scale, I have estimated the length of the snake as 13 cm.


According to Butch Norden of the Maryland DNR, whom I always turn to whenever I photograph a reptile or amphibian I can't identify, this is an immature Northern Brown Snake (Storeria dekayi dekayi). He also noted that these snakes are known to feed on slugs and snails.

In Amphibians and Reptiles of Delmarva (by James F. White, Jr. & Amy Wendt White, 2002), the length range of adult Northern Brown Snakes is given as 23 to 33 cm. So this individual has some growing to do. They also indicate that these snakes feed on earthworms, slugs and snails among other invertebrates. Perhaps it was not a coincidence that I found it where I usually find snails.

Although I am not particularly interested in snakes, they have been featured on this blog several times. The previous one was a Black Rat Snake (Elaphe obsoleta.

09 November 2008

Religion at its best: punch the one who disagrees with you

The annual rites of the ancient Christian churches in the Middle East are turning into annual rites of exemplary fighting among those who are supposed to be behaving otherwise.

The Associated Press reported that there was fighting between Armenian and Greek Orthodox monks in the Church of the Holy Sepulcher in Jerusalem (also on BBC). The reason? Petty claims of ownership of ancient structures of dubious significance.

The last year's priestly fight was at the Church of the Nativity in Bethlehem.

There you have it, folks. Tolerance, respect, peace...the virtues of religion and the religious? Love your neighbor? Yeah, right!

Stinking hypocrites.

Here is Hyphoid Logic's take on it.

So many Google Books so little time

I have an ever growing list of Google Books that I want to read. They are mostly from the 19th and the early 20th centuries. But if I attempted to read them all, I wouldn't be doing much of anything else.

I don't even bother to print most of the books anymore; I read them on my monitor. In fact, I often practice what is called skimming or skim reading.

Here are some of the Google Books I have recently read, am currently reading and planning to read in the near future. I am not putting up links to them. They all are available on Google Books. If you want them, just search for them.


The Dispersal of Shells by H. W. Kew, 1893. I have read most of this book. Despite its age, it was quite informative. What Kew meant by "shells" was, of course, live mollusks.


Letters from Constantinople by Georgina Max Müller, 1897. I have also read this one recently. Georgina Max Müller was the philologist Friedrich Max Müller's wife. In 1893, she and her husband spent some time in Istanbul visiting their son who was a diplomat at the British Embassy there. This book is a compilation of the letters they wrote back home. They had engaging accounts of their sightseeing trips, the formal friendship they had with the Ottoman Sultan Abdülhamit and the Turkish customs of that period.


Travels in Lycia, Milyas, and the Cibyratis by T. A. B. Spratt and E. Forbes, 2 volumes, 1847. Spratt was a lieutenant in the British Navy and Forbes was a naturalist associated with King's College in London. This is a detailed account of their travels in western and southwestern Anatolia in 1842. I am reading it currently and preparing an Excel file of all the place names they mention and the wildlife they encountered. It is an ideal book for skim reading.


European Animals: Their Geological History and Geographical Distribution by R. F. Scharff, 1907. This one is next on the list. I don't think I will read the entire book, but only the parts that look interesting. There are several entries on terrestrial gastropods.


A Naturalist in Mexico: Being a Visit to Cuba, Northern Yucatan and Mexico by Frank Collins Baker, 1895. This too is on the list. Baker was a malacologist specializing in freshwater and terrestrial species. When I scrolled thru the pages, I did notice pictures of some snail shells. I may print this one out so that I can read it on the train.

I don't know if I'll ever have time to catch up with the 20th century and then, the 21st century literature.

07 November 2008

Today's special: Cream of mushroom soup with fly larvae


I photographed this mushroom cluster about a month ago. They were growing at the edge of a sidewalk near College Park, Maryland. The thick "puddle" next to it, about 40 cm across, had probably been another similar cluster that was then rotting. As I bent over to take pictures, I smelled a strong, but not too unpleasant aroma coming from the rotting mushrooms.

There were many insect larvae squirming around in the soup of rotten mushrooms. I also noticed 1 fruit fly and 1 larger fly loitering around on the mushrooms. The larvae consuming the rotting mushrooms had obviously hatched from eggs laid in situ.


Mike O'Risal, who writes Hyphoid Logic, hesitatingly guessed that the subject mushrooms may be "a very decrepit bunch of something in the genus Gymnopus."

Bon appétit!

06 November 2008

Vultures during lunch break


I photographed these vultures during an after-lunch walk about a week ago near College park, Maryland. When I first saw them circling in the air, I thought there was probably a dead animal nearby that had attracted them. They were near the railroad tracks and so my initial guess was that there was perhaps a dear hit by a train. But a quick look up and down the tracks did not reveal anything resembling a carcass. Nor were there any vultures along the tracks.

Eventually, the birds perched on a pipe of the nearby defunct factory. This was the closest I could get with the small digital camera I had with me.


They are either black vultures (Coragyps atratus) or juvenile turkey vultures (Cathartes aura). I understand the 2 species can be distinguished from their wing patterns seen from below. If I see them again I will try to photograph them flying.

05 November 2008

Euconulus fulvus

I mentioned in this post that one of the land snails I found during my trip to Turkey was Euconulus fulvus.

This snail was from a mountain near Kastamonu, Turkey. Its shell diameter was ~2.3 mm.

What is especially interesting about the distribution range of Euconulus fulvus is how wide it is: the species is present throughout most of Europe*, presumably across northern Asia† and northern North America. It is what biogeographers call a Holarctic species.


Another land snail with a roughly similar distribution pattern is Zoogenetes harpa, which was the subject of this post. The explanation I offered for how Zoogenetes harpa ended up with its present distribution probably also applies to Euconulus fulvus.

*The distribution map in Kerney & Cameron (A field guide to the land snails of Britain and North-west Europe, 1979) is misleading, because it leaves southern and Eastern Europe, including Turkey, out.
I can't find exact records, however.

04 November 2008

Is it an angel? Is it Jesus? Is it our Lady of the cruising altitude? No, it's a glory


It's a glorious sight, nevertheless, and even more interesting than the other three.

A glory is a rainbow-like ring most often seen below an airplane, usually on a cloud. I took the above picture on the way to Turkey in October.

Vote today!

Fusco Brothers by J.C. Duffy

If you are a Homo sapiens of the right age (and a U.S. citizen), don’t neglect to vote today.

03 November 2008

Deer and gastropods revisited

Katherine R. Greenwald, Lisa J. Petit, Thomas A. Waite (2008). Indirect Effects of a Keystone Herbivore Elevate Local Animal Diversity Journal of Wildlife Management, 72 (6):1318-1321.
DOI: 10.2193/2007-491

Whether or not increased deer populations negatively affect terrestrial gastropod abundances and diversities was the subject of this post back in December 2005 and a subsequent note I published in Tentacle, No. 14 (starting on p. 20). Two published studies had claimed to show that overabundance of deer was reducing the numbers of some species of terrestrial mollusks. My main criticisms of those studies were that they had methodological limitations and interpretational problems.

This recent study by Greenwald et al. provides some evidence that having lots of while-tailed deer (Odocoileus virginianus) in a park may not be a bad thing after all.

The authors counted salamanders, snakes and various invertebrate taxa in 12 10x10-m enclosures from which while-tailed deer were excluded and in 12 control plots that were freely accessible to deer. The study took place in Cuyahoga Valley National Park in Ohio in 2004 and 2005, approximately 5 years after the enclosures were established.

The results show that red-backed salamander (Plethodon cinereus), garter snake (Thamnophis sirtalis) and gastropod abundance as well as invertebrate richness (no. of species or higher level taxa) were higher in control than in exclosure plots.

Fig. 1 from Greenwald et al. The thick line across each box is the median of means for over the entire study period.

So far, so good. The increased abundances of gastropods in plots grazed by deer seem to support my contention that in North American forests where the white-tailed deer coevolved with the other native inhabitants, any impact the deer present at normal or near normal population densities might have on the other native inhabitants would be a natural process and not necessarily be detrimental to them. However, my initial excitement was short-lived.

As far as gastropods are concerned, this study had a serious flaw: the counted gastropods were listed only as “slugs” without further identifications. This is a shame, because slugs are rather easy to identify by experienced workers at least to genera from external characteristics. Such identifications can be done even from good photographs. Had the authors sent out identification requests to the land snail community, I am sure they would not have been turned down.

Without additional information on what those "slugs" were, the results of this study don’t have much relevance for terrestrial gastropod research. Were those slugs introduced or native? That’s a crucial distinction in terms of gastropod conservation and even the genus-level identifications of the slugs would have been of great value.

What really matters is to know if native terrestrial gastropod species benefit from deer grazing. I hope somebody will undertake a better study to look into that. We also need a mechanistic explanation of how deer abundance may affect the populations of coexisting animals.

Many thanks to Katy Greenwald for sending me a pdf copy of her paper and for providing clarifications about the study.

02 November 2008

Osage oranges in Istanbul

One of the common Turkish words missing an exact translation in English is yokuş (yokush). It means a steep road or path. None of the English words offered by From Language to Language, including, rise, ascent, slope, incline, ramp, climb, conveys the Turkish meaning of yokuş that it is specifically a road, not just a steep slope on the side of a hill.

Istanbul, having been built on a very hilly territory, naturally has many steep roads. One of them is known as Portakal Yokuşu, the "Yokuş of Oranges", a segment of the long and winding climb, officially known as Adnan Saygun Street, that starts out in Ortaköy, passes under the Bosphorus Bridge and ends in the district known as Ulus.

I had walked up and down that street many times, but not seen any orange trees along it. So the origin of its name was a mystery until my last trip to Istanbul last month when the surprising identities of the trees lined up in a narrow median strip along one section of the road were revealed: osage oranges (Maclura pomifera).


The original range of the osage orange covered a relatively small area in southern U.S., but its range has been artificially widened by introductions to over much of the U.S. For example, they are quite common along the C&O Canal. According to a Turkish book* on the trees of the Marmara region of Turkey, osage oranges are grown in Turkey as ornamental and hedge trees.

I strongly suspect Portakal Yokuşu was named after the osage oranges, but at the moment I don't have any historical data for support.


*Tuğrul Mataracı, Ağaçlar: Marmara Bölgesi doğal-egzotik ağaç ve çalıları, 2004.