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Re: pterosaurs, bats, flying theropods



This was a remarkably cogent post, I was wondering if you, "Dino Rampage"
would offer your real name to the list, if you would?

Dino Rampage (dino_rampage@hotmail.com) wrote:

<Frankly speaking, I have never seen a chiropteran, whether micro- or
mega-, that was flying about in broad daylight. Can you provide me with
any info as to which species have actually been observed as being
diurnal?>

  Most megabats I have observed are diurnal frugivores that forage under
canopies in the tropics and subtropics.

  Banack (1998) writes of *Pteropus samoensis*:

  "This species is considered diurnal as members carry out most of their
activities in the early morning and late afternoon. This characteristic
may be a recent occurrence in the evolution of this species, as few or no
other bat species are known to be diurnal."

  This is true of all *Pteropus* species, which accoutns for the bulk of
known megabats.

  Banack, S.A. 1998. Diet selection and resource use by Flying Foxes
(Genus *Pteropus*). _Ecology_ 79: 1949-1967.

  also,

  Banack, S.A. 2001. *Pteropus samoensis*. _Mammalian Species_ 661: 1-4. 

  Her work does show that another plentiful genus, *Cynopterus* is general
nocturnal so that my statement about megabast being entirely dirunal was
wrong. My observations were largely limited to *Pteropus*. *Epomophorus*
(a fruit bat) has been observed foraging at day, but is generally a
night-feeder.

<And 'all' megabats being diurnal??? I don't think so. In my country>
(Singapore; shameless plug: recently featured in the Amazing Race 3), we
have 3 to 4 species of megabats, ranging from relatively large flying
foxes to dimunitive nectar bats, & none of them have been seen leaving
their roosts at least before 6 pm.>

  There are exceptions, I have corrected myself above.

<Do you define 'diurnal' chiropterans as being wholly diurnal, or merely 
being generalists who couldn't care less whether the sun was up or down 
before leaving the roost?>

  Diurnal versus nocturnal. I do not see problems with defining nocturnal.
However, foraging and doing feeding behavior during daylight hours, before
crepuscular hours and after dawn, is generally what I meant by "diurnal";
to reiterate, in reference to habitat.

<Whatever the case, to me the generalisation that bats are nocturnal still
holds, at least in this part of the world :\>

  This is still a generality, since in that part of the world, there are
Indonesian and Micronesian fruitbats that do forage at day. Behaviorally,
I have also observed common cave bats in the southwestern US as being
daytime foragers, but this is rare. 

<Wrong. All cats, large & small, do a high proportion of their hunting at
night. Of course, it varies from location to location, for example,
Serengeti lions are perfectly comfortable with both daylight & night
hunting, while the lions of Savuti will only hunt at night. But it is safe
to say that with the exception of the cheetah, a high proportion of cats' 
kills occur at night. Diurnal hunting is more or less a misconception 
perpetuated by documentary film crews & researchers unwilling to venture
out at night.>

  This is largely limited to rogue lions. Pride lions, cheetahs, and even
jaguars, along with snow leopards, do their hunting during the day for the
bulk of their foraging. Smaller cats, such at the puma and jagarundi, have
variable hunting styles, but the former is still diurnal, as are bobcats
and lynxes in the US, Canada, and parts of Europe. Fact is, smaller cats
are more vulnerable than larger cats, but the majority of large cats'
food-stock are similarly diurnal, including most African species, and
nearly all sizeable American (read, North America) species. Similarly,
cats have a sleep schedule that is, to say the least, erratic, and being
active at night does not make for an active predator at night. Lions still
do their share of hunting during the day (bad pun, I know). This is even
true of other trans-African species, such as hyenas, though smaller
animals such as foxes and jackals are primarily nocturnal or crepuscular
to avoid these larger predators.

<By the way, the leopard is Panthera pardus. P. onca is the jaguar.>

  Thanks, my boo. I had a headache last night, a common winter thing for
me.

<D frogmouths have broad tail fans? And if I'm not wrong, some species of 
swifts do their hunting at night. I don't think swifts have broad tail
ans...>

  This refers to maneuverability. It was not explicitly part of the
nocturnal features I alluded to. This may not have been clear. Yes, they
do have broad tail fans, and the closely related apodiforms like swifts
and hummingbirds, known for their speed adaptations, have narrow,
triangular tails with forked margin.

<Crrect me if I'm wrong, but the last time I was looking at an eagle 
soaring, it... had no webbed feet!>

  Okay, we're playing with semantics here ... for the sake of argument,
nearly all soaring birds are pelecaniform or procellariiform birds, with
webbed feet as an ancestral feature (I mentioned this); the raptorial
soarers are limited to some eagles, not all of them, and this is a
convergent adaptation based, as I can see, on size; the energetic output
for a flapper of that size would have been tremendous. Other soarers
include the large New World vultures, which were stork relatives, and
fossil pelecaniforms like the tooth-billed birds or the teratorns, are all
size-related soarers. There are no small soarers. The mechanic to soaring
is in the wing proportions, which minimizes wing effort with loading, so
that the flight can be maintained without exc3essive flapping as in
short-wing birds like woodcocks and ducks. Geese have acheived a size that
limits their ability to flap, yet migrate, so have become soarers. Do you
see what I am talking about generalities?

<Besides, which birds are true soarers? I can only recall birds like
albatross, raptors, cathartids, (do frigate birds soar? How about gulls?)>

  See above. Only some eagles. Gulls and albatrosses are procellariforms,
and nearly all pelecaniforms have soaring-built wings, including, though
not used as such, anhingas and cormorants. Geese lack the tapered wing but
are improving this by their wing bone proportions.
 
<Furthermore, I have seen several instances of crows soaring, using the 
upwellings of hot air rising from hot tar roads (something like thermals I
suppose) and these still have very strong flapping capabilities...>

  Riding thermals is not soaring. This requires heights and wing design
that crows, being stubby-wing maneuverers, lack. All birds, however,
possess the ability to hold their wings still when dropping from thermals,
or gliding. And gliding is not the same as soaring.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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