BASICS: "Hummingbirds.....where is the person, I ask, who, on observing this glittering fragment of the rainbow, would not pause, admire, and turn his mind with reverence..." (J. J. Audubon).
This is a blog about my summer life at the Baiting Hollow Hummingbird Sanctuary, at my winter garden, Calypso, in the Bahamas, and aspects of life in general.
This private sanctuary is now permanently closed to the general public, as a result of a lawsuit brought by a neighbor. Only my friends and personal guests may visit (paul.adams%stonybrook.edu).
Saturday, September 14, 2013
There are still some hummingbirds around and the weather tomorrow (sunday) looks good, so I've set up a slot in the afternoon for visits by appointment at 3 pm (ending no later than 4.30). Please email me if you would like to come tomorrow, giving the names and walking ability of those in your party, your car license number and whether you need the required waiver form. Please note you should plan to arrive in the parking lot at 3, from where you will take the woodland path starting at the yellow minibridge. The sanctuary can be difficult to find, so study the Google map (link at right), and give yourself plenty of time. This will probably be the last opportunity this year to visit.
The photo was taken at the sanctuary a week ago by Jimmy Chiu.
In my last post I described why asexual reproduction (practiced by all simple cells, such as bacteria) has a great limitation: to respond to rapidly changing environments, populations must mutate very rapidly, but if the mutation rate is too high, natural selection cannot winnow out the flow of bad mutations, and the population goes extinct. Note that this is NOT because offspring are immediately non-viable; the collapse takes a long time. Now I will try to explain why sex provides the solution to this evolutionary dilemma, and why it has become almost universal for complex life forms, such as us.
Sunday, September 8, 2013
Although we are now closed there are still a few opportunities to visit at specific, mutually-agreed times. The remaining available slots are today sunday sept 8 at 3 pm prompt and tuesday sept 10 at 10 am promptly. Please email me if you would like one of these "slots", giving the number of people, their walking ability, and your car plate #. NO visiting without appointment - we are now CLOSED.
Today's picture is a recent one by Walter Bednarczyk. The hummer is feeding at Pink Porterweed, Stachytarpheta mutabilis, a 4-star plant. The only place I know of that carries it on Long Island is, naturally enough, Long Island Hummingbird Plants.
Continuing my expurgated, rather academic, account of sex, we need to know what a "genome" is. It's simply the DNA (packaged inside cells) that carries the instructions to build that organism. Simple organisms like bacteria have a small genome, with typically only a few million units (or "bases") making up their DNA. Asexually reproducing organisms cannot evolve genomes much bigger than this. These compact genomes cannot build a complex organism - even one as rudimentary as an ameba. Why can't asexually-reproducing organisms develop the large genomes chacteristic of complex life (such as the 3 billion units of human DNA)? Remember that Darwinian evolution is all about natural selection of inherited variation. The inherited variations in asexual reproduction (e.g. by bacteria) is caused by random mistakes in copying DNA - mutations. A mutation that leads to a more-efficiently living and reproducing organism will be selected, and become more frequent in the population. This is the basic dynamo of evolution. But most mutations aren't advantageous, and will be eliminated, also by natural selection.
However, too much mutation is a bad thing. In fact, if the mutation rate is too high, evolution becomes impossible: natural selection cannot weed out bad mistakes fast enough. They accumulate and weaken the popultion to the point that it goes extinct. As a rule of thumb the mutation rate must be less than one over the genome size for evolution to operate at all. Indeed, in most simple cells the mutation rate is about a thousand times smaller than 1/genome size. This very low mutation rate reflects the elaborate and highly accurate enzymes that universally catalyze DNA copying.
But this low mutation rate, while necessary, means that evolution cannot quickly adapt to rapidly changing environments. If the mutation rate were higher (for example, comparable to 1/genome size), evolution cannot occur either. So asexually reproducing organisms are between a rock and a hard place, and can only survive by having very small genomes, sufficient only to program a simple cell. If life had stayed asexual, it would have remained an insignificant bacterial scum veiling the earth. But at some point cells learned how to reproduce sexually. As I will explain in Part 5, this turbocharged evolution, and allowed the emergence of large genomes and complex life.
Thursday, September 5, 2013
We are now closed for the season (until august 2014). However, there are still some limited opportunities for private visits by appointment only, at a few specific "slot" times. You should arrive at the agreed upon slot start time and leave before its end (1 1/2 hour maximum duration). There are 2 slots available this weekend, both in the afternoon: saturday 3-4.30 and sunday 3-4.30. If you would like to visit this weekend, please email me your choice of slot time, with the number of visitors you plan to bring, your walking abilities, and your car plate number. If I respond positively, I will meet you in the parking area at the start of the slot time to welcome you, receive your waivers and direct you over the woodland path. Absolutely no visiting outside pre-arranged appointment times.
I wrote in my last post that the key to emergence of complex life from simple life forms was the appearance (by evolution) of sexual reproduction (basically Daddy's sperm combines with Mommie's eggs to make a new individual). But before explaining why sex was so crucial, I must better explain the difference between simple and complex life. There are actually 2 types of difference, though they are related. The first is the difference between simple and complex cells. The former (basically bacteria, but also another type of recently discovered, rather obscure cells called "archaea"; the technical term is "prokaryotes") have no cell nucleus, and lack many other internal structures that are found in complex cells. These cells have been around for about 4 billion years, and emerged quite quickly after the earth formed. They reproduce asexually (though they can swap genes). Complex cells are bigger, have sex, nuclei and various other things like mitochondria (which provide increased levels of energy). They are known scientifically as "eukaryotes".
The second type of simple/complex difference is between single celled organisms and multicellular organisms (like us: we are made of about one hundred trillion complex cells, excluding the quadrillion bacterial simple cells in our gut; a blue whale might have a hundred quadrillion cells). All multicellular organisms are made of complex cells, but there are many single-celled complex organisms (such as amoebas).
It seems as if sex is necessary to make complex cells and even more necessary to make multicellular assemblies of complex cells (like us). In my next posts I will explain (1) why asexual (e.g. vegetative) reproduction cannot generate either type of complexity (2) why sex does the trick. After explaining why sex is necessary, I will explain why it's difficult to do properly.
The image, showing a bird pollinating a rosebud sage, is by Keith Bittner. A hummingbird has "only" about 100 billion cells.
Wednesday, September 4, 2013
Last night we had the first proper sunset since at least a week. The wind shifted to the north west, the air dried and the visibility and light improved greatly. Hummingbirds were quite active until at least 15 minutes after sunset, making up for lost time. It was too late for them to take advantage of the wind shift to depart southward. Around sunset itself there was a lot of chasing going on around the front deck overlooking the sea: clearly very young hummers were desperate to feed in the fading light, but the owner(s) of the flower beds were ruthless in chasing them away. I tried to take video but I have not yet reviewed the outcome - I hope to post some results soon. Then one by one they all vanished - except that when I thought all was over, a shy bird came to feed unmolested in the last light. He spent at least 6 minutes feeding continuously, flitting from flower to flower, occasionally perching on a stem for a second or so before resuming. I have never seen such a long feeding episode before - clearly a single bird. Finally, as the light disappeared, he headed off towards the gloomy forest.
Today's photo is a recent one by Maria Dottavio. While the sanctuary is now closed until aug 2014, there are still some opportunities to visit privately, either as a group (minimum 10 people) or by appointment at specified "slot" times. One available slot is friday at 3.30; others may be available sat am/pm and sunday pm - please check the blog for details, or email me.
Resuming my account of the mystery of sex, I can recommend a book on the topic by Mark Ridley (who wrote one of the very best standard texts on evolution). The book is for the "intelligent layman" (or, rather less neatly, "intelligent layperson" - in fact "very intelligent layperson"!). There are 2 versions around: "Mendel's Demon" (the original UK title) and "The Cooperative Gene" (the US title). I prefer the former title, since it gets more to the heart of the matter, and also alludes to a related idea, "Maxwell's Demon" (which would itself be a nice topic for a future post, if ever I can link hummingbirds to statistical physics!). "Mendel's Demon" refers to the way that in sexual reproduction genes from the 2 parents are shuffled together in the offspring, rather like a hand of cards that contains both red and black suits. The book explains why the sexual shuffling process is essential to get complex organisms (multicellular organisms that contain many different cell types, and which are visible to the naked eye - essentially life "as we see it" rather than "life as we know it", which includes invisible single cell organisms such as bacteria. In fact he argues, correctly I think, that the most important thing about life is not that it exists, but that it exists in complex forms. Many planets might carry simple forms of life, but only on a few very favorable planets did life assume striking complex forms, such as trees, tigers and us. Furthermore, he argues that the key to the appearance of complexity was not Darwinian evolution itself, but the development of sex. More to follow.......
Tuesday, September 3, 2013
We are now closed until august 2014. A few slots are available for visits by appointment - see below.
Today's photo was taken on sunday by Rick Mei. Notice the little dab of golden pollen near the base of the bill. Typically a flower's anther places pollen on the bill or forehead of the probing bird. This is then transferred to the next flower's stigma, achieving cross-pollination. But since most plants can also reproduce vegetatively, or asexually, why do most prefer to reproduce sexually, by cross-pollination? Oddly enough, this simple question is still not completely answered by modern evolution theory. Creationists could rightly claim that evolution theory is incomplete, but luckily they don't like to talk about sex.
The simple answer is that sex is almost universal because it promotes genetic variety (as we all know), which is useful in a complex and ever-changing world. However it's not easy to prove that this is the case. The main problem is that sex is in other ways extremely inefficient: if an organism reproduces "vegetatively" (i.e. asexually, e.g. by budding) it generates twice as many offspring: sex takes 2 organisms rather than 1. Sex remains the "Queen of Evolutionary Problems", since it has not been conclusively shown that the sexual bargain is a good one, in the long term ("do my genes have a better chance of surviving if I reproduce sexually or asexually?"). I'll write more about this fascinating but rather abstruse topic in future posts. In the mean time, let's enjoy the complicated sex lives of hummingbirds and flowers.
Visiting by Appointment. ONLY NEW VISITORS (i.e. no previous visit this year; past years ok) WITH WAIVERS. NO VISITING OUTSIDE OF THESE TIMES and then ONLY IF YOU RECEIVE EXPLICIT PERSONAL APPROVAL BY EMAIL FOR YOUR PARTICULAR REQUESTED TIME (print out my email to you and bring please). NOT transferable to other times. YOU MUST STATE IN YOUR REQUEST (title your email "Slot Request") THE NAMES of all your accompanying car passengers and your car license plate number. INDICATE THOSE WHO HAVE ANY DIFFICULTY WALKING so we can make appropriate arrangements. ALL VISITS SHOULD LAST NO LONGER THAN 1 1/2 hours. AM slots start the trail prompt at 10, pm slots prompt at 3; you should arrive a bit before your slot time (but only start the trail on time; I will greet you in the parking lot). It can be difficult to find us so give yourself plenty of time. No late-comers please.
AVAILABLE SLOT TIMES: tuesday sept 3 am, friday sept 6 pm only. Email me your slot choice, giving the names and walking ability of all members of your party. Thanks.
Monday, September 2, 2013
We are now closed until august 2014. However, there are still a few opportunities to visit by private appointment (e.g. this afternoon, tues both am and pm, and friday afternoon). For details see below.
We have hardly seen any sun at the sanctuary for a week, and everything (including me) is a bit soggy. Hummingbirds are still hanging in there, and I'm still going through a jug of nectar every 2 days. After 2 lectures last week the new semester really gets underway on wednesday, so I'm catching up with some garden chores.
Today's photo, by Robin Fishman, shows a rather skinny, long-necked, hummer feeding at rosebud salvia while clinging to a flower stalk. Most of the other hummers here are rather plump, and waiting for an improvement in the weather, and a nice tail wind, to go further south. Hummers try to perch when feeding whenever possible, though usually they have to hover. Of course the ability to hover is the key to their success, because it enables them to compete with insects for the nectar provided by so many flowering plants. This novel (for birds) ability allowed the hummingbirds to diversify into one of the largest avian families, with over 340 species, exclusively in the New World. Some Old World species do nectar (e.g. sunbirds), but much less efficiently.
A few slots are available for visits by appointment. ONLY NEW VISITORS (i.e. no previous visit this year; past years ok) WITH WAIVERS. NO VISITING OUTSIDE OF THESE TIMES and then ONLY IF YOU RECEIVE EXPLICIT PERSONAL APPROVAL BY EMAIL FOR YOUR PARTICULAR REQUESTED TIME (print out my email to you and bring please). NOT transferable to other times. YOU MUST STATE IN YOUR REQUEST (title your email "Slot Request") THE NAMES of all your accompanying car passengers and your car license plate number. INDICATE THOSE WHO HAVE ANY DIFFICULTY WALKING so we can make appropriate arrangements. ALL VISITS SHOULD LAST NO LONGER THAN 1 1/2 hours. AM slots start the trail prompt at 10, pm slots prompt at 3; you should arrive a bit before your slot time (but only start the trail on time; I will greet you in the parking lot). It can be difficult to find us so give yourself plenty of time. No late-comers please.
AVAILABLE SLOT TIMES: monday sept 2 pm only, tuesday sept 3 am/pm, friday sept 6 pm only. Email me your first 2 slot choices if you want a slot, giving the names and walking ability of all members of your party. Thanks.
Sunday, September 1, 2013
We are now (as of sunday sept 1) closed for the season. We will re-open in august 2014. However, a few slots are available for visits by appointment. ONLY NEW VISITORS (i.e. no previous visit this year; past years ok) WITH WAIVERS. NO VISITING OUTSIDE OF THESE TIMES and then ONLY IF YOU RECEIVE EXPLICIT PERSONAL APPROVAL BY EMAIL FOR YOUR PARTICULAR REQUESTED TIME (print out my email to you and bring please). NOT transferable to other times. YOU MUST STATE IN YOUR REQUEST (title your email "Slot Request") THE NAMES of all your accompanying car passengers and your car license plate number. INDICATE THOSE WHO HAVE ANY DIFFICULTY WALKING so we can make appropriate arrangements. ALL VISITS SHOULD LAST NO LONGER THAN 1 1/2 hours. AM slots start the trail prompt at 10, pm slots prompt at 3; you should arrive a bit before your slot time. No late-comers please.
AVAILABLE SLOT TIMES: sept 2 pm only, sept 3 am/pm, sept 6 pm only. Email me your first 2 slot choices if you want a slot, giving the names and walking ability of all members of your party.Thanks.
Hummers activity will remain good at least until mid-september, and we can also take private photography, birding or gardening groups at pre-arranged, limited times. Such groups must have a minimum of 8 members. Please email me to arrange a group visit.
I thank all my visitors and blog readers for their interest, respect and enthusiasm this year. While it's not been a great year either in terms of hummer activity, or smooth operation, I think that all visitors saw hummingbirds, and enjoyed coming. I've received and greatly appreciated many nice emails and other comments. The blog will continue until all the hummers depart further south, around mid-october, or until I run out of new photos, so PLEASE KEEP up the flow of photos! There will be occasional posts about significant hummer events on Long Island (and check out my posts back in february this year for great photos of a local overwintering rufous hummingbird).
If you have a correctly completed (signature, printed name, date) waiver on file, this remains valid for next year. I will generate a list of the names of those for whom I have a waiver on file, and if you find your name on this list, no further waivers need be filed for future visits (e.g. august 2014). Even if you filed a waiver but cannot find your name on the list, you will need to complete a new waiver next year.
This will be freely available online and at the sanctuary itself. If you have requested but not yet received waiver access permission, I will be sending emails apologizing; no more waiver access permissions will be granted this year since we are now CLOSED. Waiver access will be universal next year.
Today's photo is another by Joe Maggio.