** Dennis Paulson wrote -

>
> Thoughts? You bet.
>
> I thought readily apparent El Nino effects were limited to oceanic
> creatures such as fish and birds. They are affected by changes in oceanic
> food resources brought about by temperature changes and are big enough to
> be noticed. One might consider a Brown Booby a likely vagrant from these
> changes, although I hadn't noticed an increase in booby records in
> California recently. Has there been a booby incursion farther south? And
> how far are birds likely to vagrate (to coin a new verb) under these
> conditions? Brown Pelicans, Heermann's Gulls, and Elegant Terns have always
> flown north during their nonbreeding season, and the terns are merely
> following a normal pattern but flying farther when they come up our way,
> perhaps because they don't find enough to eat in California.

A narrow view of things, Dennis. I am sure the floods in Africa, the drought in
Australia, and the smog from forest fires in Indonesia are all "readily apparent
El Nino effects" to the inhabitants of the affected areas, both human and
otherwise. As for the vagrancy of Elegant Terns, etc., it is not the fact that
their is an annual vagrancy, but the statistically significant increase in
numbers of vagrants during an El Nino. I believe Mike Patterson has already
crunched some numbers for his section of Oregon.

> We've had some pretty severe El Nino years in the past decades without any
> apparent vagrancy, right?

I would imagine so due to the fact that one El Nino is always different in some
respect than another. There is just too much chaos in the system to expect
that the same exact conditions would ever repeat themselves.

> Am. Oystercatchers might be affected by changes in intertidal food
> resources, but I had not heard of El Nino causing this to occur, and this
> species has remained rare in California even with the increase in birders
> there over the years. Nevertheless, I see it as a real possibility. Some of
> you may not know about the record from Idaho in April 1981, a really
> shocking occurrence. It would be great if the Marysville bird could be
> relocated and photographed to be sure of the subspecific (and even the
> specific) identification. I don't suppose the observer thought of
> distinguishing between American and Eurasian as this surprising bird flew
> past.
>
> Of course, caracaras and hummingbirds wouldn't be affected by marine food
> resources.

Unless there were Caracaras which subsisted on seaside carrion...

> El Nino, of courses, also changes weather on a broad scale. Is there
> anything about weather patterns in, say, northern Mexico, that would
> increase the likelihood of vagrancy?

Well, "Nora", for one, brought 300 mm of rain in 24 hours to the southern Baja
when it crossed. The return period for such an occurrence is likely at least
100 years. And many west coastal sections of Mexico were inundated by floods
last summer. Perhaps a historical food source of either the hummer or caracaras
was affected.

> I don't know if I can buy the idea
> that a hurricane crossing Baja would displace a Xantus' Hummingbird or
> caracara all the way up here. I suppose either species could get blown onto
> a boat offshore that was heading up this way, but what would they eat? I
> can envision crew members putting out food for a caracara, but how about a
> hummingbird? They need to eat constantly to survive, and I doubt if ships
> routinely carry hummingbird feeders.

Agreed. Hurricanes could not act as a transport medium in this case given the
trajectory of the cyclone and its remoteness from Gibsons, BC. However, it
would have a high probability of being a transport initiator away from its
home range.

> Parenthetically, with the abundance of Caribbean hurricanes, and the high
> frequency of Caribbean and Atlantic seabirds being seen up and down the
> Atlantic coast and even inland (see the last Field Notes), I don't recall
> reading about a single West Indian *land bird* turning up north of Florida
> on the Atlantic coast. The Bahamas are full of land birds that don't occur
> in the U. S. Does anyone know of such records? Perhaps this should be our
> clue?

Hurricanes are usually a boreal late summer and fall occurrence. At that season,
most boreal-breeding migrants are on their way south, not north. In fact, in
El Nino years the Atlantic hurricane mechanism is suppressed while the east
Pacific basin enjoys an increase in hurricanes - exactly what happened in the
summer and fall of 1997. I take it you mean the Field Notes edition which
summarizes the fall of 1996 season (spring 1997 edition).

You are correct in stating that seabirds vastly outnumber landbirds as
apparent hurricane-transported vagrants. I believe the obvious answer to this
is that hurricanes spend 99% of their lifespan over water and thus would have a
much higher likelihood of sucking up seabirds than landbirds. Also, seabirds do
not as a rule fly to ground purposely during heavy weather whereas landbirds
do.

> The other alternative is just plain vagrancy, independent of global
> perturbations, and 4 species in a year from the same region (presumably)
> does seem to be more than usual.

Ignoring global perturbations is something that we humans had better not continue
to do.

> However, bear in mind that there are more
> birders all the time and--maybe even more important--more communication
> about birding, and it may be in part that there are always lots of unlikely
> birds in any given area but that we're learning about more of them now. I
> don't know the history of the booby discovery, but the caracara, the
> hummingbird, the oystercatcher, and the Yellow-throated Warbler were all
> reported by people who weren't part of the active birding community, I
> think. A Summer Tanager--first for Washington--spent part of this winter at
> the feeder of such a person on the Skagit Flats, another such example. I
> feel strongly that improved communication is increasing the number of
> rarities detected.

No argument there. There was a booby discovered in Hecate Strait in BC during the
last El Nino episode (it was described as a Blue-footed but was not accepted
by the bird records committee as such. Either way, the description left no
doubt that it was a booby of some kind). The discoverers were in a passing
sailboat at the time and were educated about birds enough to know that they
were seeing something that should not have been there. So increased public
education in addition to technological advances in communication are working
together to increase the frequency and distribution of reports of vagrants.

> And think of how many there must be! We don't really think that everyone
> who sees a bird at their feeder that they can't identify immediately calls
> the local Audubon society, do we?

Indeed!

> Finally, about captivity: we take for granted nowadays that many of the
> exotic waterfowl we see must be escaped captives, because they're so far
> from their normal range, although they scarcely ever have bands or
> indications of captivity. I suspect that birds of more kinds than we think
> are kept nowadays as pets/captives, both legally and illegally, and that
> this is always at least a possible alternative to bonafide occurrences of
> far-out (in the sense of the 60s) vagrancy.

Perhaps. If a bird of paradise landed in my backyard, I would assume that it
was an escape. However, any N. American species I would consider a possible
vagrant (except maybe a wrentit!).

- Jack





------------------
Jack Bowling
Prince George, BC
jbowling at direct.ca

cc: dpaulson at ups.edu