[CT Birds] Threat recognition

[David.F.Provencher at dom.com]

Threat recognition in an organism is a fascinating topic to me. Birds
appear to be able to distinguish between different species of raptor, or at
least different genera. If the raptor is an actual predator of the bird in
question, an evasion strategy occurs. If the raptor is not a predator of
the bird in question, then there will be some level of surveillance the
bird will apply to the raptor's presence but there seems to be an
understanding that there is no imminent threat. Is this innate or learned?
Another interesting threat recognition behavior I've witnessed is how
shorebirds react to approaching humans. If you walk along a beach towards
shorebirds they will allow you to approach to within a certain distance and
then move away or flush. However if you approach them from the water, say
wading out into a couple of feet of water depth, they will allow a much
closer approach before reacting. So do they perceive the level of threat
differently because they perceive you differently, or do they perceive a
different level of threat because of what you are doing differently?

Mobbing, such as John mentioned, is another form of threat
recognition/reaction. Mobbing seems to be an innate behavior. Certainly the
behavior spreads across the species barrier. But  why would Blue Jays mob a
Shrike? Certainly the Blue Jays are unlikely to have each been the target
of Shrike attacks. Perhaps they have witness attacks on other birds and the
aggressive behavior exhibited by the Shrike triggers the mobbing reaction
to the now imprinted Shrike/predator image the Jays have acquired. To muddy
the already murky water let me ask this, why are Blue Jays rarely if ever
mobbed by other birds? Certainly they are aggressive and predatory at
times.

Threat recognition/reaction in birds can be immensely helpful to birders
watching for predators as well. The first Gyrfalcon I saw in CT was being
mobbed by three Northern Harriers (Hammonasset). The Gyr was perched
mid-level in a tree and I might have never looked there if not for the
spectacle of three Harriers swooping and wheeling.

Dave



-----------------------------------------
CONFIDENTIALITY NOTICE:  This electronic message contains
information which may be legally confidential and/or privileged and
does not in any case represent a firm ENERGY COMMODITY bid or offer
relating thereto which binds the sender without an additional
express written confirmation to that effect.  The information is
intended solely for the individual or entity named above and access
by anyone else is unauthorized.  If you are not the intended
recipient, any disclosure,  copying, distribution, or use of the
contents of this information is prohibited and may be unlawful.  If
you have received this electronic  transmission in error, please
reply immediately to the sender that you have received the message
in error, and delete it.  Thank you.