Counting hummingbirds

From: "Mark Klym" <Mark.Klym@TPWD.STATE.TX.US>
To: <HUMNET-L@listserv.lsu.edu>
Sent: Wednesday, June 06, 2001 12:39 PM
Subject: Someone Looking For Trivia

> I got a call from someone wanting to know the approximate amount of nectar
> consumed per hummingbird per day. Any help????

Date: Wed, 6 Jun 2001 13:49:06 -0700
From: Sheri Williamson <tzunun@mindspring.com>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: Someone Looking For Trivia

Here's a link that will help:

Audubon Kern River Preserve: How Many Hummingbirds?
http://frontpage.lightspeed.net/KRP/our_hummingbirds.htm

The page cites Ruth Russell's calculations (based on Bill Calder's studies)
that a gallon of sugar water can fill the daily energy needs of about 750
Black-chinned-sized hummingbirds. The page offers the following
your-mileage-may-vary qualifications to this formula:

*Not all hummingbirds are Black-chinned Hummingbirds.
*Not all hummingbird individuals or species are the same size which may
impact sugar solution intake.
*Not all hummingbird species or individuals are known to drink the same
amount of sugar solution.
*The length of the feeding day differs depending upon latitude and
longitude.
*Feeding rates and consumption may vary depending upon temperature and other
weather related factors.
*Migrating hummingbirds may require more food than non-migrating
hummingbirds.

A different slant is that they can drink about one and one half times their
weight in liquid nectar each day, which at varying nectar concentrations
(thanks, Dennis) comes out to between 20 and 45 percent of their weight in
sugar.

Sheri Williamson
Bisbee, AZ
tzunun@mindspring.com

==========================

Date: Wed, 6 Jun 2001 16:51:14 -0500
From: Lanny Chambers <lanny@HUMMINGBIRDS.NET>
Reply-To: BB for Hummingbirds and Gardening for them in the Southeast
<HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu
Subject: Re: Someone Looking For Trivia

On 6/6/01 14:39, Mark Klym Mark.Klym@TPWD.STATE.TX.US wrote:

>I got a call from someone wanting to know the approximate amount of nectar
>consumed per hummingbird per day. Any help????

Presumably, they're trying to estimate how many birds they're feeding.
But that's not a good way to go about it, because even if they
successfully estimate losses from evaporation, drippage, and insects,
they can't know what other food sources the birds are using between
feeder visits. Further, I think all the estimates i've seen--which vary
quite a bit--were measured under laboratory conditions, not the
rough-and-tumble real world of hummers.

I like Nancy's method: count all you can see, and multiply by 6. I doubt
any other system is more accurate.

Lanny Chambers
St. Louis, USA

=======================

Date: Mon, 3 Jun 2002 12:20:25 -0400
Reply-To: BB for Hummingbirds and Gardening for them in the Southeast <HUMNET-L@listserv.lsu.edu>
From: BB for Hummingbirds and Gardening for them in the Southeast <HUMNET-L@listserv.lsu.edu>
Subject: Re: [HUMNET-L] Consumption calculations...
To: HUMNET-L@listserv.lsu.edu

From:SJPeterson@AOL.COM@listserv.lsu.edu on 06/03/2002 12:20 PM EDT

Allen,

The following web page may help answer your question. It
is based on calculations by Steve Russell which in turn
were based on energetics studies conducted on
Black-chinned Hummingbirds by the late Dr. Calder.

http://www.valleywild.org/our_hummingbirds.htm

Essentially, one liquid ounce consumed per day suggests
nearly 6 Black-chinned-sized hummingbird equivalents are
feeding at the feeder per day. Extrapolate that further
and you'll note that one gallon of sugar water consumed
per day suggests about 750 Black-chinned-sized
hummingbirds are feeding per day.

I think the above calculations are done assuming no
turnover. And there are a zillions other variables which
can effect that number...

Best,

--Stacy

^v^...^v^...^v^...^v^...^v^...^v^...^v^...^v^...^v^...^v^
Stacy Jon Peterson
4442 Sijan St. Apt. A
Mtn Home AFB, ID 83648
Elmore County; USDA zone 6a; Sunset zone 3
SJPeterson@aol.com
^v^...^v^...^v^...^v^...^v^...^v^...^v^...^v^...^v^...^v^
HUMMINGBIRDS: www.geocities.com/trochilids
^v^...^v^...^v^...^v^...^v^...^v^...^v^...^v^...^v^...^v^

========================

Sent by: BB for Hummingbirds and Gardening for them in the Southeast <HUMNET-L@listserv.lsu.edu>
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To: HUMNET-L@listserv.lsu.edu
cc: (bcc: James V Remsen/najames/LSU)
Subject: Re: [HUMNET-L] Consumption calculations...

This is pretty close to what Ross Dawkins and I came up with working with a
marked population at Dan Brown's near San Angelo several years ago. We used
marked recapture of birds at roughly 2 week intervals and used at least 3
sessions to make estimates and get confidence limits. The population was
considered closed because it was during the breeding season and there were
few migrants passing through this area in spring. We estimated a population
of roughly 3000 birds using 3 gallons of sugar water per day. This comes to
about 4 grams per Black-chin per day during the breeding season. There was
pretty large confidence limits and volume consumption appears to be useful
for trends in populations during the breeding season.

Brent Ortego
202 Camino Drive
Victoria, TX 77905Sent by:

=====================================

Humnetters and Dr. Ortego
The system you and Dr. Dawkins used was on a relatively stable population of breeding birds. I think this is the key to estimating the actual population. Once migration gets underway, all bets are off in my opinion. A very few banded and color-marked birds (Ruby-throated) will hang around the feeders for days or even weeks, but the vast majority will "hit it lick or two" and be gone until late next summer!

During my banding in late summer/fall, I can reasonably expect to capture 5 or 6 hummers for each bird that I THINK I SEE IN THE YARD AT ONE TIME. Nan's more conservative estimate of 4-5 to 1 may better stand the test of time.

There are a lot of hummers out there all the time, but during the breeding season few places will have large numbers detected at feeders. As more hummingbird banders come on line, we are discovering more and more places that have "clusters" of breeding birds at feeder locations. I don't expect that we will approach the numbers of Black-chinneds at Dan Brown's Ranch in Texas, but who knows for sure. What we know about the breeding population and distribution of hummingbirds you could put in your ear.

How does one factor in the population of fledgling Downy Woodpeckers that have discovered my hummer feeders? MG and I have at least 13 of these screamers that compete with Ruby-throated at our feeders!

Bob Sargent
Trussville, Alabama

=====================================

BB for Hummingbirds and Gardening for them in the Southeast <HUMNET-L@listserv.lsu.edu>
Please respond to BB for Hummingbirds and Gardening for them in the Southeast <HUMNET-L@listserv.lsu.edu>
To: HUMNET-L@listserv.lsu.edu

Subject: Re: [HUMNET-L] Consumption calculations...
I have weighed Rufous Hummingbirds as they fed though the course of a winter
day. I have had some days when a hummer was very faithful to the one feeder,
and a near complete record of its consumption was recorded. Using three
different Rufous, I picked 10 days that were near completely documented. The
average weight of nectar consumed was 9.4 grams per day with a range of
8.2 - 11.6 grams. The concentration was about a 1 to 4 ratio sugar to water.

Dave Patton
Lafayette, LA

====================

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To: HUMNET-L@listserv.lsu.edu

Subject: Re: [HUMNET-L] consumption calculations a la' Sluggo
re: Dennis Demcheck, typing for Sluggo, Questioning our arrogant, elitist
Terra-centric viewpoints in Baton Rouge, La., Earth

Humnet: Is there no beginning to this man's wisdom?
Do I seem like the type who could be drawn into a pernicious Humnet debate?
It does seem that, once controlling for ambient air temperature, photoperiod
and circannual hormonal synergies, which directly impinge on the
thermoregulatory energy expenditures and field metabolic rates of diverse
foraging strategies, one might best look on the other end of the hummingbird
for the varying proportions of excreted sucrose, glucose and fructose in
their excreta, revealing sugar assimilation rates dependent on sucrose
hydrolysis and carrier-mediated glucose absorption mechanisms. Only after
controlling these independent variables can we begin to meaningfully study
the relationship between nutrient density (i.e. sugar concentration) and
volumetric intake, which on Planet X, is inverse.

See you in 54 days, after Louisiana's First S. rufus detection,

John Sylvest

========================

Date: Tue, 23 Jul 2002 13:56:14 -0500
Reply-To: BB for Hummingbirds and Gardening for them in the Southeast <HUMNET-L@LISTSERV.LSU.EDU>
From: BB for Hummingbirds and Gardening for them in the Southeast <HUMNET-L@LISTSERV.LSU.EDU>
Subject: Re: [HUMNET-L] Sugar Consumption Amount Formula

Humnetters:

Getting very accurate numbers of hummers using an area is very difficult.
Various methods can be used and for the most part within a season they
probably work as a trend for that situation.

On the central coast of TX, I can generally catch during a day 10X the
number of birds reported at a feeder during migration. During the breeding
season, its more like 3 - 4 times this amount. In migration, the
population of birds frequently changes completey every day, at the longest
it takes 3 days to totally replace birds. This is a very dynamic, fluid
population of birds passing through and you can basically identify quantity
in general terms like abundant, common and scarce. Who knows how many you
have on a given day or period.

During a short term study of a breeding population in central Texas, we
used banding to do marked recapture population estimates of a stable
population. This technique only works if you have a closed population
(birds are not enterring or leaving during the period of study). The
population in Dan Brown's yard was large. Dan was using 2 dozen gallon
feeders and birds were consuming about 3 gallons per day. We made 3
consequtive banding efforts at 2-week intervals where we caught at least
100 birds per trip and compared number of banded during previous visit to
the number of unbanded during each trip. The first population estimate was
3000 and the 2nd was 3100. This is relatively close agreement even though
looking at each estimate separately showed very large confidence limits.
In this fairly stable setting, we estimated 1 gallon of sugar water used
per thousand of black-chinned hummers.

In reality, because of many variables associated with sugar consumption,
conspicuousness of hummers, proximity of other food sources like your
neighbor with the great yard, etc., establishing abundance is just an
educated guess in most cases. For yourself, Use a technique than can be
replicated in your yard/study area and use it as a trend for your location.
It can be sugar water consumption, birds observed per 30 minutes in close
proximity to sunrise, sunset, noon, etc. The exact method is not as
important as replicating it in the exact way each time.

This fall we are going to try and look at differences of movements and body
conditions of birds along the TX coast at hummingbird expressways along
rivers and bays versus along the back road migration routes. I have a
hypothesis that birds not on the migration expressways are not migrating as
fast and are of poorer body condition for migration. We will see if it is
correct.

Brent Ortego
202 Camino Drive
Victoria, TX 77905
361/576-0022 office
361/578-4155 fax
361/572-9848 home
>From: Nancy L Newfield

>
>Allen,
>
>At 01:03 PM 7/23/2002 -0400, Allen Chartier wrote:
>
>>Count ALL the birds you see in a 30
>>minute period to determine the number of birds (I think Nancy
>>Newfield has
>>quoted this one to me before). This may be less accurate, in my
>>opinion, as
>>two birds visiting at 15 minute intervals might get counted twice,
>>or even
>>three times, when in reality all there are is two birds, or maybe
>>four.
>
>Nope. Not me. Unless, you are dealing with individually marked
>birds, you
>have no way to count the true number of hummers you might be seeing
>in any
>particular interval of time. My system has worked well with fairly
>large
>aggregations and with much smaller ones as well - using color-marked
>birds. It is true the situation may be very different in Michigan,
>but I
>can't tell you the number of times "1 adult male" has turned out to
>be 3 or
>4. With females, the situation may be more extreme.
>
>>Another problem of trying to use actual consumption to calculate
>>numbers is
>>unknown amounts of spillage, as has been mentioned.
>
>Add to that usage by other creatures. That's the reason I don't
>care for
>that method.
>
>Still, all these methods are only estimates.
>
>NLN
>
>***************************
> Nancy L Newfield
> Casa Colibrí
> Metairie, Louisiana USA
>