Date: Fri, 31 Aug 2001 09:48:31 -0700
From: Ron Rovansek <ron@NVWETLANDS.COM>
Reply-To: BB for Hummingbirds and Gardening for them in the Southeast
<HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: [HUMNET-L] traplining

Karen,
As we humans envision things, there are two basic approaches a hummingbird can use in securing enough flowers to keep itself full of nectar. One is to find a nice big patch of flowers (or flowers and a feeder) and stay there. The problem with
this approach is that there might not be a big patch available, or another
hummer might already have claimed the patch. i guess, for lack of a snappier name, we call this "defending a territory". The other strategy is to visit a series of flowers that are spread out over several suburban lots, several miles of
jungle, etc. Humans imagine that visiting these flowers a couple of times a day must mean that the hummer follows a regular path from one clump of flowers to the next, much the same way a human trapping animals for fur would set out a series of traps and follow the "trapline" every day to see what's been caught. So, some humminbirds tend to defend territories, some tend to trapline. I suspect all species, and
certainly this is true of all North American species, will use either strategy
or a combination of the two depending on the situation. in Louisiana in the
winter, blackchinned hummingbirds tend to be trapliners, especially where rufous hummingbirds are defending territories. the traplining blackchins sneak into the yard and feed for a few minutes, then are off to the next yard. I, for one,
doubt that the presence of territorial hummers in a yard ever actually keeps other
hummers, like blackchins, completely away. I think it just makes them act as
trapliners who visit a couple of times a day and while in the territory of
another hummer make themselves as inconspicuous as possible. This of course makes them harder to observe, and leads some observers to believe that they (the
non-territorial hummers) are being excluded from the yard, when I think that
they are there but hard to find.

Ron Rovansek
Reno, NV

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Date: Fri, 31 Aug 2001 11:16:56 -0500
From: Van Remsen <najames@unix1.sncc.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] traplining

On Fri, 31 Aug 2001, Karen & Andy Taylor wrote:

> OK, What's traplining???
> Karen Taylor

Karen/HUMNET: "traplining" is used by hummingbird biologists to refer to a
feeding strategy in which a bird visits isolated food sources over a large
area, possibly using a regular route. For example, an individual
wintering hummingbird might run a regular route from feeder to feeder over
a large area of suburbs, never spending much time at a particular yard.
The term was first applied, I think, to the various hermit hummingbirds
(genus Phaethornis etc.) that have home ranges of 1-2 square km in
tropical forest, and they "trapline" between isolated flowers or patches
of flower scattered through that home range, spending a lot of their time
n transit from one flower patch to the next. The home range is too large
to defend effectively, and individual flowers don't provide enough food to
warrant constant territorial defense.

This contrasts with more typical "territorial" spacing pattern in which a
hummer stakes out a rich patch of flowers (or feeder) that yields enough
food through the day to make it worth fighting for.

Trapliners may try to sneak into defended territories, depending on
stealth to get a sip or two before being discovered by the more
aggressive, dominant territorialist.

These categories are useful, but as always, individual or temporal
variation may prevent totally "clean" categorization. Naturally, there
are other categories of space use, too.

Van Remsen,
LSU Museum of Natural Science,
najames@unix1.sncc.lsu.edu

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Date: Fri, 31 Aug 2001 09:56:27 -0700
From: Sheri Williamson <tzunun@mindspring.com>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: [HUMNET-L] foraging strategies

In addition to territoriality and traplining, hummingbirds use another
foraging strategy, territory parasitism, in which a bird "steals" nectar in
a territory held by another bird. In most cases this applies to tiny birds
such as Bumblebee and Little Hermit who sneak in for a sip when the dominant
Blue-throated or Rufous-tailed has its back turned, but in areas where
nectar is plentiful enough that true traplining isn't necessary big
trapliners such as Magnificents and Long-tailed Hermits become de facto
territory parasites.

Sheri Williamson