(posted in Birds)

Hi Cale,
               Not all birds have crops. Birds that do use them as a means of storing food before flying to a favoured spot to get on with digesting their meal. As for the gulls swallowing starfish, starfish are not rigid, so it is not as awkward as it might seem.


Dave H and Dave W,
                                 Thanks for pitching in!

(posted in Birds)

Hi Bob,
            Firstly, I very much doubt this is any sort of hybrid. The Green Woodpecker Picus viridis and the Great Spotted Woodpecker Dendrocopos major belong to different genera, which means there would be strong reproductive isolation between the two species.

The simplest explanation would be that you saw a green woodpecker that has some mutation that has resulted in different plumage. None of the European woodpeckers has the colour combination you describe, and it doesn't look like a juvenile/immature colour combination. Someone else on the site with more knowledge about variations in woodpecker plumage may be able to comment.

You sound familiar with the woodpeckers, but if the light was bad or angle of illumination was unusual then this might also have created the impression of different colours. I often make colour mistakes during  the winter when I am out birding due to variable light.

Sorry not to be more help.

Hi Jeremy,
                    Firstly, thanks for telling us where you are in the world and for posting such an excellent photograph. Take a look at the link, everyone!

From having a look at my field guide I think this is a female damselfly, possibly either a Common Blue Damselfly Enallagma cynthigerum or a Common Coenagrion Coenagrion puella . However, it is quite difficult to make an ID on these from books and I am no expert on the group. Someone else on the site may be able to work out what it is.

Can I suggest that you contact this British Dragonfly Society for an ID?
I think they would also be interested in using your photo on their website. It is a really excellent photo!


Hi Andrew,
                    The number of leaves on a clover is under genetic control.

http://mulch.cropsoil.uga.edu/~parrottl … /index.htm

Variation in the expression of the number of leaves is, I'm afraid, not evidence of speciation. Plants do have some interesting speciation mechanisms based around their ability to self-fertilize and double their number of chromosomes.


Sorry to disappoint you, but I hope the articles are of interest.

(posted in Mammals)

Hi Hanna,
                  I presume you mean bats biting people. The people I know who have been bitten in the UK are all folks who do bat research and/or conservation. From a quick search on the web, it is a fairly rare occurrence among the general public. Bat teeth are usually quite small and do not often break human skin.

However, your IP has resolved to Guangzhou in China. If this is where you live, and you or someone you know, has been bitten by a bat I would advise you to seek medical attention as some species of bats in southern China carry rabies.


(posted in Plants & Fungi)

Hi Margaret,
                      Menthol is one of a large group of chemicals called terpenoids that plants secrete to discourage animals from eating them.

(posted in Birds)

Sorry Rudi, changes in what way? Size, plumage?

Hi Rudi,
                I think you mean myriapods (centipedes and millipedes). Yes, they are predatory, but have been known to eat vertebrates as well as invertebrates.

More on Wikipedia

(posted in Birds)

Dear Rudi,
                    Your IP is resolving to around Embsay in North Yorkshire, so I am basing my comments on that. I've had a look at distribution maps on British Trust for Ornithology website, which I'm afraid aren't available to people not registered with the BTO, and you should be able to see fieldfares no problem in North Yorkshire.

Fieldfares, in my experience, are often found in flocks in winter in open farmland areas, and like to feed on berries in hedgerows. They have a very distinctive call.

You can read more about them and hear the call on the RSPB website here:
http://www.rspb.org.uk/wildlife/birdgui … index.aspx

You've posted quite a few questions on the site about different topics, but if you are partcularly interested in birds, find out about RSPB and Wildlife Trust activities in your area.


(posted in Birds)

Hi Wendy,
                   Birds will use nestboxes to roost in during the winter quite routinely. It is a warm, secure place for them.

This project at Aberystwyth University has a bit more about winter roosting in nestboxes.


Hi Don,
               Can you let us know where you are in the UK? Your IP address resolves to a central server in Hampshire. It would also help us if you could tell us a little more about your garden.

You might also want to take a look at Buglife, who might be interested in your footage, as might BBC Autumnwatch


(posted in Evolution)

Hi Garry,
                 A lot of terminology exists around species (the entities or objects) and speciation (the process that creates the entities). An additional source of confusion is that some names for speciation processes can also refer to patterns. The terms you list in the first part of your question refer to how much geographic overlap there is during speciation. Sympatry means there is full geographic overlap, allopatry means no geographic overlap exists during speciation.

To answer your question fully, we need to explore the ideas and terminology a bit more to try and clear things up for you and other readers.

When thinking about speciation it is important to remember that the process is not about one species becoming a new species. It is about a populations (the next unit down from species) splitting and then evolving sufficient differences to stop exchanging genes. A large number of processes can be involved in stopping the flow of genes. But being on either side of a mountain range or ocean is one excellent way to do this. Hence the focus on allopatric speciation. Allopatry is a single-step process, and is easy to observe and demonstrate. This is why it is so widely accepted as a speciation mechanism. When we represent this sort of process on evolutionary trees we will show one branch splitting to become two branches.

Anagenesis IS a way of generating a new species that involves gradual change. But it does NOT involve a splitting of populations.  What is crucially different about the species involved is that, although they would be recognized as separate species in the fossil record, they would probably not be true species under the speciation process explained above. This is because this evolutionary mode involves all of the members of the population changing form, which I must stress can represent evolution and natural selection, but the two species we recognize are in an ancestor-descendant relationship, or can be thought of one continuous twig on an evolutionary tree. The branch does not split.

This creates a problem for classification. If we want our classification to reflect the true evolution of the group, then we would have to define the two anagenetic species as a single species. However, it has often been the case in the past that palaeontologists have named sufficiently different forms as separate species.

Here is a link to a discussion on Wikipedia. It seems succinct to me, but that is probably because all the terminology is familiar to me.

There is a longer article available on Talk Origins in the Macroevolution section, which has diagrams that will help to explain the idea of branching patterns

Please let us know if this clears things up for you. And anyone else on the list, please add comments.

Hi Issac,
                Do you mean the Latin binomial name for slugs? Each species of slug will have a different name, but as an example, the European Red Slug (the common name) has the Latin binomial
Arion rufus.

Hi Abi,
              You will get a lot of different answers from different people. Some of the common pieces of equipment used by many biologists working in the field are:

- Binoculars
- Hand lenses (for magnification)
- Quadrats (to sample equal areas in plant surveys)
- Rulers, tape measures, callipers (all for measuring)
- Camera
- Scales (for weighing)
- Field notebooks
- Maps
- GPS units
- Field Guides and identification keys to identify specimens
- Laptop computer or personal digital assistant (PDA), often adapted for fieldwork
- Audio recording devices

After that it depends a lot on the organisms you are working on.
- People who work on ringing birds will carry special equipment for putting the rings on.
- People who study bats use 'bat detectors' to hear the calls
- If you work on nocturnal insects you may use a light trap
- For collecting insects that live in leaf litter many people carry a little device called a 'pooter',      which acts like a little vacuum cleaner powered by your breath.
- Some organisms are easier to see under ultra violet or 'black' lights.

The equipment used varies whether you are working on aquatic, terrestrial or airborne animals, but the nature of the project and the sort of organisms you work on are also very important in determining what equipment you take with you into the field.

(posted in Birds)

       If you are posting from the UK, another possibility is the Green Woodpecker http://blx1.bto.org/birdfacts/results/bob8560.htm. In his collected book of birding articles 'Gripping Yarns' Bill Oddie says that whenever someone who isn't familiar with birds described a weird-looking bird then the Green Woodpecker is a good bet.

You may also find the RSPB Bird Identifier helpful in future. http://www.rspb.org.uk/wildlife/birdidentifier/. It works by narrowing things down by asking you a series of questions and encapsulates the logic of how to go about identifying a bird based on the place you saw it, the size etc.

I hope this helps, and please let us know if one of us got it right or if you manage to work it out yourself. It is nice to get feedback!

Steven J. Gould argued in his 1977 book Ontogeny and Phylogeny that the human chin was a non-adaptive trait that was the result of differential growth rates in two bones in the lower jaw.

This article makes an article based on biomechanics of chewing for the adaptive significance of the human chin.
http://www3.interscience.wiley.com/jour … 2/abstract

I can't read the full article and don't have any theories of my own. But always good to see ideas being revisited.

(posted in Birds)

Pigeons, and their relatives, produce crop milk. This is produced by both parents and is very nutrient-rich. Pigeons mature quite quickly, so you have a relatively short window to see them as 'squabs'.

(posted in Fossils)

Hi Thomas,
                    Two thoughts. It may be an ammonite preserved in a side-on fashion or it may just be a pebble. It doesn't look structured enough to be a fossil from the photos.

As a wee anecdote, when I was an undergrad in Glasgow there was a chameleon in the Zoological Museum that would charge anyone who got too close and smack into the glass. Not the most tolerant of creatures....

Hi Christin,
                   I don't think we have any marine mammal biologists among the AAB crew, and we tend not to answer these on site. I know the University of St Andrews in Scotland has several marine mammal people, as does the British Antarctic Survey. The Marine Biological Association may also be able to help you.

Good luck with your project.

This from Dr Kevin Page, University of Plymouth,

Probably nothing reliable since Howarth 1973 I think it was (Bull BMNH and I think he included commune) – D.commune ss

To translate out of academic speak, this was published in the Bulletin of the British Museum (Natural History) in 1973.

Howarth, M. K. 1973: The stratigraphy and ammonite fauna of
the Upper Liassic Grey Shales of the Yorkshire Coast. Bull
Br. Mus.
Hist. (Geo!.) 24, 237-277

The ss part at the end means sensu stricto (with the tight meaning).

I hope this helps with your project

Good to see people taking an interest in the world of medical testing, as I spend a lot of time railing against case-based studies and arguing with my friends who are medical doctors about the value of such work. For a lot more on the world of trials and statistics as applied to medicine Ben Goldacre's Bad Science book and website are excellent.


I would also recommend Dave Colquhuon's  website

Two points worth making from a broader statistical viewpoint.

1. Randomization is regarded as the key to proving causal relationships, not using the same individuals with both treatments. I suspect that there may be some confusion in this question between the statistical use of population (all of the individuals of interest) versus a sample (some subset of the population of interest that we can get results that are then generalizable across the whole population). Apologies if the original poster was clear about this. Differences in the use of the words 'population' and 'sample' are the source of endless confusion between statisticians and biologists.

2. I am not from a medical background, unlike David W, but I work with data that can loop to the same set of values in through time. A familiar example would be temperature through an annual cycle. If there were similar effects in a drug study (female menstrual cycle in a test using adult females as an example off the top of my head) I would be worried about such effects interfering with my analysis.

So I am glad that the randomized, double-blind control trial is still regarded as the only suitable test for licencing drugs, although I think the approach by the Cochrane Library, which uses metanalyses to boost sample sizes thus allowing quicker evaluation of the effect of drugs is brilliant.

They also have a part of their site that deals with assessing methodologies

One for the people who work on human subjects.

Are there any ethical problems with the crossover trials? If such a design meant that people who could have benefited from getting a drug were delayed in doing so, would this be ethical grounds for not permitting such a design to be used.

        I am away from my main body of ammonoid references at present, but a good publication to look up would be

W.T. Dean, D.T. Donovan, M.K. Howarth : The liassic ammonite zones and subzones of the north-west european province, BMNH, London 1961

I am also going to contact a friend who works on Early Jurassic ammonites and see if he has an electronic list. So watch this space.

(posted in General Biology)

Hi Nick,
              Not my field of specialization, but I'll explain what I can. How curly your hair is depends on the shape of each strand of hair (folicles) in cross-section. If you have a perfectly round folicle you get straight hair, the more oval the folicle, the more curly it will be. I don't know about the coordination, I think it may be that people with wavy hair appear to have more 'order' as their individual hairs are curling less rapidly than people with very curly hairy.

If you want to get an idea of different curves, compare different sea shells, the shape of these is determined by the shape of the area where the animal lives and how rapidly growth occurs. Some shells have very oval cross-sections and grow fast, leading to very tight coils. Others have more circular cross sections and are 'fatter'. Classic UK garden snails are a good example of this.

Hope this sates your appetite until someone with molecular knowledge can pick up that part of your question.

(posted in Evolution)

I presume that you mean a logical condition, as used in computing. I think John Holland's definitions relating to the conditions for complex adaptive systems are really useful. His book 'Hidden Order' looks at complex systems in general and I think is a more helpful place to start than trying to define 'life' or 'organism' as there can be rather slippery categories.

Holland's idea is that there are seven key elements a system needs to meet the sort of conditions you are interested in, split into four properties and three processes. I can't find my copy of the book right now, but the diagram on this wikipedia page will give you some flavour


If you want to know more, please post again and I pick the brains of my office mate, who does a lot more work on theoretical biology.

You can see some animations of the DNA double helix at the following URL
http://www.countingthoughts.com/ct/inde … animations

You will have to wait for the bloodflow movie to end, and then the DNA sequence will run.

(posted in Birds)

Waterfowl and game-birds also have many hybrids. We know quite a lot about this because so much data has been gathered from hunters. Duck hybrids are common enough to have a couple of pages devoted to them in my field guide. I don't have any information on the sterility of these hybrids to hand.

Ah, a cephalopod question for a change!

The reproductive strategy of octopodes is similar to many other cephalopods, except for Nautilus. Octopodes hatch from smallish eggs, grow for a year or two then mate. They only mate once in their lives, which is called semelparity, then die. The male usually dies rapidly after mating, the females guard the eggs then die. As an ammonoid worker, I can tell you that we assume this is also the case for ammonoids, based on the small size of their eggs and the fact that they are more closely related to squid, cuttlefish and octopodes than Nautilus.

If you want to know more about this group of molluscs, The Cephalopod Pages, http://www.thecephalopodpage.org/,  are a great resource and have some wonderful photos and movies.

As a public service announcement, octopuses, octopi and octopodes are all plurals that enjoy some support in different dictionaries. my attitude is that if people know what you mean, that is fine. Language is for communication, not point-scoring!

Snakes are not always immune to their own venom (Wikipedia has a story of a cobra that bit itself and suffered an abscess as a result), but there is considerable evidence that some snakes are immune to venom from both their own species. However, a quick trawl of the web indicates the debate rages on.

I have a dim recall of a story about a gabon viper biting itself and dying, but I can't give a source.

(posted in Fossils)

This from Dr Rebecca Price, at University of Washington. She worked on gastropods for her Ph. D.

"The way we determine whether a fossil species was carnivorous is by analogy to modern families. Within the neogastropods, for example, only a few very derived extant species are NOT carnivorous—and that’s a very large clade. Another way to determine if there were predatory gastropods around is to look for drill holes—of course, octopuses drill holes too, so when we conclude that it was a gastropod drilling the hole, we’re looking at drill hole shape and assuming that all snails and all octopuses have had stereotyped drilling shapes through time."

The latter part of her answer will tell you whether predatory drilling gastropods does not tell us whether a particular species is carnivorous, only that some sort of driller is present. As a cephalopod worker, I can confirm that it is usually fairly easy to distinguish between gastropod and octopod drill holes

As an aside, there are two ways this question could be interpreted. I suspect Mike provided the answer that was being sought: an estimate of the number of species. However, another answer would be how many individuals among all inverterbrates (what is referred to as abundance) there are. This is another aspect of biodiversity that maybe doesn't get as much coverage as it should. Just as the number of species in larger groups varies a lot, so does the number of individuals. When we tally up how many individuals per species are found in different areas, we often find the same patterns. A few species will be represented by many individuals, while most species will be represented by only a few individuals. Such relationships are very important in our understanding of how ecological communities work and is an important topic in an area of ecology called macroecology.

(posted in General Biology)

Dear All,
                Animals tend to do well when human interference is limited and access to areas is tightly controlled. Although this does not relate directly to war, many military training areas are major havens for wildlife. Salisbury Plain in the UK is managed for conservation and I knew a couple of the ecologists employed by the MOD when I lived in Wiltshire.

A German military training area in south-east Germany has become one of the few areas inside Germany with a wolf population.

As a public service announcement, I should take a moment to dispel one myth about Chernobyl. Yes, there has been some increase in both the number of individuals and number of species found relative to areas outside the main irradiated area. However, this is due to the effects discussed above, rather than radiation being beneficial. Ecologists and biologists have performed numerous studies inside the restricted area, which have been very important for getting baseline data on the effects of radiation on ecosystems, particularly low-level radiation. After the atomic bomb attacks at Hiroshima and Nagasaki, no-one knew what to expect, ecology was still a fairly young science, and techniques for studying genetic problems were in their infancy.

Currently the Royal Society of London has open access to its journal archives for about another four weeks
and a search on Chernobyl will find many of these studies, mostly on birds.

Hi Alex,
                I wanted to quibble with your use of the term "evolutionary progression". Many evolutionary biologists and palaeobiologists don't consider evolution to be a progression. Different taxa have different characters, some of which make humans go, "Wow". But in terms of other measures of biological success, single-celled organisms and bacteria rule the world's ecosystems.

To get a better idea of how evolutionary biologists think about relationships among organisms, Dawkin's "The Ancestor's Tale" is very good. Some people who work on the relationships among organisms would even go so far as to say it is very difficult to ever put taxa in ancestor-descendant relationships. We can still garner a huge amount of knowledge from knowing the relative closeness of relationships among organisms, although new discoveries can often alter our estimates of those relationships.

Hi Dave,
               Nautilus, and we suspect ammonoids, drain the chambers by osmosis. For the sake of clarity, as far as we know they do this only once when they finish constructing a chamber. They do not seem to be able to voluntarily control this after the chamber has been completed. So they do not use this to actively control their buoyancy for the purposes of vertical migration.

              I wonder if what you saw might be a hoverfly of some sort. Here are some images in from a Google image search

http://images.google.de/images?hl=de&am … amp;tab=wi

Have a look and see if they match with what you saw.

Dolphins are also capable of attacking and killing sharks by ramming attacks.

A quick reprise of the Popper business first.

Popper advocated a particular type of argument in his earlier work. He then made the famous statement about evolution not being science, because it was not "hypothetico-deductive" and incapable of setting up "critical experiments". He later changed his views, possibly because some biologists explained what evolution DID predict, and actually came to see the evolution of philosophical ideas as a type of selection process. Anyone who uses Popper's earlier statements probably hasn't read his books, which I admit can be tough going. I recommend Michael Ruse's books, as they deal with evolution from a philosopher's point of view but are not laden with jargon.

Biology and astronomy have the problem that they are both historical sciences and much of the work done in these fields is often related to coming up with the best general explanation of classes of phenomena. The technical name for this is inference to the best explanation, but to give you an idea of how this works, look no further than Sherlock Holmes. Although Holmes claims to use deduction, he in fact uses induction (technically abduction). He looks at the data and comes up with the best explanation for all the facts. Sometimes Holmes gets it wrong, because another explanation is possible, or the facts do not lead to an inescapable conclusion the way they do in genuine deductive logic.

To address the more practical part of your question, it is hard to make future predictions about a lot of issues. Conservations biologists are quite good at predicting extinction, based on current environmental needs of species (see the work of J. H. Brown and his group at Arizona) but the difficulty is that there are very few cases in which we have any significant grasp on the interaction between  genes, both with each other (epigenetics), and the environment which results in the organisms we see (phenotypes). Evolution in the lab is one thing, evolution in the field is another with a lot of variables.

The more fruitful approach to think about evolution and its predictions is to ask whether observed examples of structures, behaviours and other aspects of biodiversity are in agreement with the concept that:

1. More individuals (insert your level of selection here) are born than can survive
2. Variation exists among those individuals
3. That variation is heritable to some degree

With some exceptions, explicable by other theories such as sexual selection, much of life on Earth can be explained by application of this formula.

An interesting footnote to this question. A study into blushing noted what David spotted, that women blush more than men. The argument is that it is a signal of honesty (and thus carries a cost) and shows that you care about being truthful. So it is evidence for David's first hypothesis.

I'm afraid this was something I caught on Radio 4 and can't, as yet give a link to the study.

Brachiopods have a lot less muscular tissue than molluscs, so are probably not worth the effort, unless you really need the protein.

A short discussion of the issue can be found here
http://www.manandmollusc.net/molluscan_ … onchl.html

"Lamp shells" are the common name for Lingula, the inarticulate brachiopod. I have heard various versions of the "eating articulate brachiopods makes you sick" tale repeated on the discussion thread.

Both my parents are left-handed, both my sister and I are right-handed, so we are examples that demonstrate it is not impossible for two left-handed parents to have right-handed offspring.

(posted in Research and Careers)

     I did physics and chemistry and mathematics at school in Scotland, never did biology and I have managed fine. As a postdoc, I find it is my computer programming and statistics skills that are in demand and allow me to tackle research questions rather than my natural history skills. As Paolo says, physics is really useful in some areas of biology, such as biomechanics. Many brilliant biologists started out as mathematicians and physicists, so it is no barrier.

(posted in Fossils)

Hi Justin,
                  Just to check, was this found at Clashnessie in Assynt near Lochinver? There are several caves with fossil mammals in the area It would help if you could send a photo to us at

As I am not a mammal specialist, I am going to demure from an ID at the moment.

At the risk of the automated banning system taking against this post, I should point out that it is unlikely that sexual, rather than natural selection, is involved. Sexual selection usually involves mating preferences and I am unsure how a human female would signal that she had a difference in the angles involved to make her more attractive to potential mates.

Apologies for the pedantry.

(posted in Research and Careers)

In a museum that is part of a university to do most of my palaeobiological work, and skulking in fields, woods, mountains and the garden for my "contributions" to ornithology.

The short answer is yes. it is not very likely, but it can happen. I remember a story of a geneticist who went into genetics because of this very issue. Hopefully the molecular types can give you more detail.

(posted in Mammals)

The oldest confimed bat fossils are from the Eocene (55 Mya). Many famous fossils, with soft tissues, have been found in the Messel oil shales in Germany, but the oldest fossil is Icaronycteris from the Green River Formation in Wyoming. Molecular studies have indicated that bats probably appeared before this, but you are right that the bat fossil record is poor. Some teeth from the Paleocene (a slightly older interval that comes directly after the Cretaceous) have a mixture of bat and insectivore characters.

The idea of "transitional fossils" is a bit of a red herring. We know from anatomy that bats are mammals and can postulate a common ancestor with other insect eating mammals.

If you have other, more detailed questions, write in and I can pass them on to my bat buddies.

(posted in Evolution)

Jon, Dave,
                  I think what the pupil was probably referring to are the intermolecular bonds between hydrogen molecules (also know as Van der Waals forces). The molecules involved in this type of bond do need to be in close proximity, but there are plenty of other types of bonds and forces out there to hold molecules together. So in a few words; tosh and cant.

Methinks this sounds like a standard creationist gambit, ask the scientist about an area of science they don't work in and if they can't answer the question then creationism must be valid. Worth checking if they are being primed by parents or others. Don't get any hits about this on creationist sites, though. Googling intermolecular forces gets me straight to Van der Waal bonds.


(posted in Mammals)

Hi Paolo,
               While my wee girl has no problem putting her feet in her mouth, I am a bit puzzled that as an adult male (heavily fused spine and all) that I would have no difficulty cleaning my hind paws like a bear. Am I odd for an adult human?

What Dave is describing is known as "lucid dreaming" and is common enough to have been the focus of quite a bit of research

There is the famous story of Friedrich August Kekulé  dreaming about the ring structure of benzine as a snake biting its own tail.

For my own tuppenceworth on the matter, when I am working on computer programs and get stuck I sometimes dream the answer. This is a not uncommon experience among programmers.