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ANUROGNATHIDS & VAMPIRISM



David Peters wrote...

---------------
On "Walking With Dinosaurs" the narrator says that 
anurognathids spent their entire lives snapping up the 
insects attracted to sauropod hide. Is this hypothesis in the 
literature? And if so, what is the reference?
---------------

Obviously Martill and I chased this up for the _Walking 
With Dinosaurs: The Evidence_ book we did (we may or 
may not mention it.. can't remember). Tim Haines came up 
with the idea based on the obvious analogy with oxpeckers 
(_Buphagus_): there's nothing more to it than that AFAIK.

Firstly, oxpeckers are reported to have particularly recurved 
claws and other hindlimb features that assist in clinging to 
ungulate hides: this is often asserted but I don't know of any 
functional study that 'demonstrates' it. While oxpeckers do 
keep down the numbers of ticks present on large ungulates 
according to some studies (most notably Stutterheim et al. 
1988: as a consequence they've been deliberately introduced 
to areas [e.g. Shamwari Game Reserve] with tick problems), 
they don't just eat parasites and biting insects - they eat a lot 
of snot, dead skin, blood and earwax (in fact one study 
showed that Cape buffalo deprived of oxpecker attention 
soon had ears so full of wax that their hearing was 
impaired). Yum. 

In fact some authors have argued that blood is the preferred 
food of oxpeckers (Bezuidenhout and Stutterheim 1980, 
Weeks 1999) which makes it unlikely that they are 
beneficial to their hosts and raises the possibility that they 
are on their way to specialised vampirism (which obviously 
is documented elsewhere in passerines: _Geospiza 
difficilis_). Most recently Weeks (2000) has proposed that 
mammal-oxpecker interactions are more complex than most 
authors have thought and that oxpeckers may be parasitic on 
some animals (on hippos they apparently only feed on 
wounds), commensal on others and mutualistic on others.

Bezuidenhout, J. D. & Stutterheim, C. J. 1980. A critical 
evaluation of the role played by the red-billed oxpecker 
_Buphagus erythrorhynchus_ in the biological control of 
ticks. _Onderstepoort Journal of Veterinary Research_ 47, 
51-75.

Stutterheim, I. M., Bezuidenhout, J. D. & Elliott, E. G. R. 
1988. Comparative feeding behaviour and food preferences 
of oxpeckers (_Buphagus erythrorhynchus_ and _B. 
africanus_) in captivity. _Onderstepoort Journal of 
Veterinary Research_ 55, 173-179.

Weeks, P. 1999. Interactions between red-billed oxpeckers, 
_Buphagus erythrorhynchus_, and domestic cattle, _Bos 
taurus_, in Zimbabwe. _Animal Behaviour_ 58, 1253-1259.

Weeks, P. 2000. Red-billed oxpeckers: vampires or 
tickbirds? _Behavioural Ecology_ 11, 154-160.

See the following for a good reference list on oxpeckers...
http://www.uct.ac.za/depts/fitzpatrick/docs/r771.html

--
Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045