gmr044@leah.Albany.Edu (Gregg Recer) (08/02/90)
Various posts have brought up the idea that summer/fall feeding of
birds might interrupt normal migration behavior in birds so fed. I
think there's no strong generalization that can be made about this
issue. I doubt very much that bird species with strong migration
tendencies will hang around in great numbers just due to the presence
of some feeders in a typical non-winter-range area. On the other
hand, some populations in which not all individuals are strongly
migratory may respond to additional food availability in fall and hang
around. Northward range expansions of some species such as N.
Cardinals and N. Mockingbirds have been explained, at least in part,
by this kind of effect. I believe this kind of thing has helped
Anna's Hummers expand their range north as well, yes?
I guess the main point is that, for migratory species, the main
cue to which they respond is day-length. Shorter light cycles cause
physiological changes that result in a whole suite of behaviors
leading to (in our case) migration southward. Most often, food levels
are correlated with decreasing day length (insects, e.g. die or become
inactive as fall progresses) so the advantage in migrating may be in
moving to areas with more food but the main cue to which the birds
respond is not food per se but light (light cycle-length is a whole
lot less variable from year to year than is food abundance so it's a
more useful cue). In species where the response to the light cue is
not real strong food levels could act as a secondary cue to modify
migratory behavior.
One condition that is not generally a factor in this is
temperature. Birds are typically quite well adapted to surviving cold
temperatures. So hanging around in the cold northern winter, wouldn't
necessarily be a "disaster", as someone suggested, assuming there was
sufficient food around. The main reason the typical winter-resident
bird species here in the northeast are chickadees, nuthatches,
woodpeckers and finches is that these species can either dig dormant
insects out from under bark, etc. or can subsist pretty much entirely
on various seed crops available in the winter.
As a side note, with regard to sugar-water for hummer feeders,
nectar, which I'm sure hummers eat without incident, is sugar water
(basically fructose instead of sucrose). This soft-bill idea is
pretty silly, seems to me.
Gregg
*******************************************************************************
"In future you should delete the words crunchy frog and
replace them with the legend crunchy raw unboned real
dead frog!!"
-- Inspector Bradshaw, The Hygiene Division
*******************************************************************************phz@cadence.com (Pete Zakel) (08/04/90)
> As a side note, with regard to sugar-water for hummer feeders, >nectar, which I'm sure hummers eat without incident, is sugar water >(basically fructose instead of sucrose). This soft-bill idea is >pretty silly, seems to me. Well, the nectar I use (Perky-Pet nectar mix) is sucrose and dextrose. One variety of Perky-Pet nectar has added vitamins and minerals (and less food coloring and no preservatives). Although they might not *need* the extra vitamins and minerals, I can attest the fortified nectar goes *much* faster than the regular stuff (although that could be because they like having less food coloring, I suppose, or perhaps the lack of preservatives in the fortified mixture attracts them more...). Also, although the Anna's hummers in the San Francisco bay area are resident according to my Peterson's, I think their winter range is different from their summer range as I get much less activity around my feeders in the winter months (even though I leave them out all year round). I suppose I could switch to straight sugar, but I like the fact that the nectar has finer granules which dissolve better (undissolved sugar in the nectar is very bad for hummers for the same reason honey is bad -- can cause infection on a hummer's tongue which frequently means death...), and Perky-Pet claims the food coloring they use is safe for hummers (I believe they switched from one variety of colorant to another recently for this reason) -- and the coloring makes it easier for me to know when the feeders need refilling. -Pete Zakel (phz@cadence.com or ..!{hpda,versatc,apollo,ucbcad,uunet}!cadence!phz)
mjm@oliven.olivetti.com (Michael Mammoser) (08/09/90)
In article <9008040052.AA25409@cds709.noble.com>, phz@cadence.com (Pete Zakel) writes: > > Also, although the Anna's hummers in the San Francisco bay area are resident > according to my Peterson's, I think their winter range is different from > their summer range as I get much less activity around my feeders in the > winter months (even though I leave them out all year round). There are reports that Anna's Hummingbirds may move from higher elevations to lower elevations in winter. Although I don't know about the birds further north, the Anna's in the San Francisco Bay area are here year round. One must be careful about deducing hummingbird population trends from watching a feeder; in that hummingbirds may abandon feeders if natural food sources become abundantly available. In my personal birding experiences, I haven't noticed any significant seasonal variations in the population of Anna's Hummingbirds in the Bay Area. Mike
john@nmt.edu (John Shipman) (09/05/90)
Pardon my skepticism, but my science teachers trained me not to let blind assertions of fact pass unchallenged. I want published sources describing well-designed, double-blind experiments. Casual observation doesn't really prove anything. Pete Zakel (phz@cadence.com) writes: +-- | Although [hummingbirds] might not *need* the extra vitamins | and minerals, I can attest the fortified nectar goes *much* | faster than the regular stuff (although that could be because | they like having less food coloring, I suppose, or perhaps the | lack of preservatives in the fortified mixture attracts them more.... +-- How do you know that the contents of the nectar are the sole factor in the hummers' decisions? What about the location of the feeder, the shape of the nozzle, the percentage of sugar, and hundreds of other variables? +-- | I suppose I could switch to straight sugar, but I like the | fact that the nectar has finer granules which dissolve | better (undissolved sugar in the nectar is very bad for | hummers for the same reason honey is bad -- can cause | infection on a hummer's tongue which frequently means death...), +-- Sources, please---other than Perky-Pet's self-serving literature. Also, it *is* possible to get sucrose completely into solution. Try using warm water, or stirring a lot. -- John Shipman/Zoological Data Processing/Socorro, NM/john@jupiter.nmt.edu ``Let's go outside and commiserate with nature.'' --Dave Farber
sandra@pyrtech.pyramid.com (Sandra Macika) (09/05/90)
In article <1990Sep4.190206.6103@nmt.edu> john@nmt.edu (John Shipman) writes: > >Sources, please---other than Perky-Pet's self-serving literature. >Also, it *is* possible to get sucrose completely into solution. Try >using warm water, or stirring a lot. >-- >John Shipman/Zoological Data Processing/Socorro, NM/john@jupiter.nmt.edu I tried using warm water once and the birds did not drink it. The feeder stayed out there full for a long time until I finally refilled it using cold water. Does amyone know why this might have happened? Thanks, Sandra
phz@cadence.com (Pete Zakel) (09/08/90)
john@nmt.edu (John Shipman) writes: }Pete Zakel (phz@cadence.com) writes: }+-- }| Although [hummingbirds] might not *need* the extra vitamins }| and minerals, I can attest the fortified nectar goes *much* }| faster than the regular stuff (although that could be because }| they like having less food coloring, I suppose, or perhaps the }| lack of preservatives in the fortified mixture attracts them more.... }+-- } }How do you know that the contents of the nectar are the sole }factor in the hummers' decisions? What about the location }of the feeder, the shape of the nozzle, the percentage of }sugar, and hundreds of other variables? It's always the same feeders, in the same locations, with only the contents changing. The two feeders always have slightly different contents (I switch between all three Perky-Pet nectars and the two feeders always each have a different nectar). The "Light" nectar is *always* consumed faster, no matter which of the two feeders contains it. Since the feeders and locations remain constant, I conclude the difference must be in the nectar. }+-- }| I suppose I could switch to straight sugar, but I like the }| fact that the nectar has finer granules which dissolve }| better (undissolved sugar in the nectar is very bad for }| hummers for the same reason honey is bad -- can cause }| infection on a hummer's tongue which frequently means death...), }+-- } }Sources, please---other than Perky-Pet's self-serving literature. }Also, it *is* possible to get sucrose completely into solution. Try }using warm water, or stirring a lot. I never said it wasn't possible to get sucrose completely into solution. I simply stated a preference for the finer granules in the Perky-Pet *because* they dissolve easier and faster. My sources are direct eyeball observations of store-bought granulated sugar and Perky-Pet nectar. Or are you claiming that undissolved sugar is harmless to hummers? -Pete Zakel (phz@cadence.com or ..!{hpda,versatc,apollo,ucbcad,uunet}!cadence!phz)
john@nmt.edu (John Shipman) (09/09/90)
Sandra Macika (sandra@pyrtech.pyramid.com) writes: +-- | I tried using warm water once and the birds did not drink | it. The feeder stayed out there full for a long time until | I finally refilled it using cold water. +-- I hadn't noticed this, because I usually mix a large batch of solution with warm water and then refrigerate it. Pete Zakel (phz@cadence.com) writes: +-- | It's always the same feeders, in the same locations, with | only the contents changing. The two feeders always have | slightly different contents (I switch between all three | Perky-Pet nectars and the two feeders always each have a | different nectar). The "Light" nectar is *always* consumed | faster, no matter which of the two feeders contains it. +-- I didn't realize Perky-Pet had three different formulations. What are the differences? +-- | Since the feeders and locations remain constant, I conclude | the difference must be in the nectar. +-- A reasonable conclusion. But is the difference in the composition of the nectar, or in the concentration? A number of people I've talked to tell me that hummers prefer stronger solutions. Perhaps Perky-Pet's formula is simply sweeter. In an earlier posting, Mr. Zakel asserted: +-- | undissolved sugar in the nectar is very bad for hummers | for the same reason honey is bad -- can cause infection | on a hummer's tongue which frequently means death... +-- I would still like to see some reasonable support for this assertion. Perky-Pet might be pushing this point of view as a scare tactic to sell more of their expensive stuff, so I wouldn't believe their literature. -- John Shipman/Zoological Data Processing/Socorro, NM/john@jupiter.nmt.edu ``Let's go outside and commiserate with nature.'' --Dave Farber
phz@cadence.com (Pete Zakel) (09/11/90)
john@nmt.edu (John Shipman) writes ['}']: }Pete Zakel (phz@cadence.com) writes ['}|']: }I didn't realize Perky-Pet had three different formulations. }What are the differences? Original -> Sucrose/dextrose with food coloring. Strawberry -> Artificial strawberry flavoring added. Light'n'Sweet -> Much less food coloring and vitamins and minerals added. }| Since the feeders and locations remain constant, I conclude }| the difference must be in the nectar. } }A reasonable conclusion. But is the difference in the }composition of the nectar, or in the concentration? A }number of people I've talked to tell me that hummers }prefer stronger solutions. Perhaps Perky-Pet's formula }is simply sweeter. I doubt that Perky-Pet is sweeter than plain sugar -- I assume it *is* just cane or beet sugar in finer granules. But you did point up one thing that I don't control absolutely -- the concentration. The directions call for one heaping teaspoon per 2 ounces of feeder capacity. It is possible that the concentration varies enough so that my observations aren't completely valid. Since I'm not trying to prove anything, I tend to think that random fluctuations should even things out. If I really want to test this (which I may some day) I will make sure to use a gram scale to accurately measure the dry nectar. }| undissolved sugar in the nectar is very bad for hummers }| for the same reason honey is bad -- can cause infection }| on a hummer's tongue which frequently means death... } }I would still like to see some reasonable support for this }assertion. Perky-Pet might be pushing this point of view }as a scare tactic to sell more of their expensive stuff, }so I wouldn't believe their literature. Actually, it may be. I have read about honey being bad in several sources, so I trust that, but I haven't read anything about table sugar causing a problem so I have to admit I could be blowing hot air (to put it politely). In any case, the house I am moving into in a couple of weeks was owned by birders before me, and they say they have both Anna's and Rufous hummers visiting their feeders, as well as Hooded and Western (I think) Orioles. And recommended a good birding spot (Coyote Hills?) nearby (Fremont, CA). Since I haven't positively IDed a Rufous hummer, I'm looking forward to spotting some (I think I had one migrating through my yard a week or so ago, but I couldn't get a good enough look at it to be sure). This morning, though, I heard a mockingbird imitating a car alarm -- a first for me. I've heard them imitating bullfrogs before but this was the first car alarm imitation I've heard. -Pete Zakel (phz@cadence.com or ..!{hpda,versatc,apollo,ucbcad,uunet}!cadence!phz)