A Plethora of Hummingbirds

[Norm Dulak]

Around the first of April each year, we set out hummingbird feeders. And true to form, hummingbirds faithfully return from their winter retreats to greet us. This year we welcomed two pairs of Ruby-throated hummingbirds, including the female shown here. As summer approached, we saw a few more hummers that we thought might be babies of our couples. But as we continued to feed them, it became apparent that family expansion alone could not account for all of the sugar water consumption we observed.

Now, we fill each of three feeders twice each day, using a total of about six cups of sugar water. A little web research indicates that each 3-4 gram Ruby-throat may consume about 10 calories per day. And some calculations suggest that we thus must have at least about 30-40 Ruby-throats at our feeders!

So it seems that we have attracted many other friends and customers to our feeders. That may make us the hummingbird fast food center of Kent County, Maryland!

Norm

[Eric Weaver]

That's a lot of hummingbirds at one feeder! Looks like the word is out on who feeds the best in your neighborhood! I'm the opposite but I hadn't had one out in several years and didn't get this one out until July this year. Nonetheless after a few days a pair staked their claim to it. They are a joy to watch. I never tire of it.

[Ulli Hoeger]

Hummingbird migration is in full swing and you may have a few transients refueling on your feeders.
However, hummers are not the only feeder guests. Wasps, ants, and alike take their share and over time I have seen feeders starting to drip and loos fluid that way.

Ulli

PS Not sure where you got the 10 calories a day number. There is at least a k missing .......

[Norm Dulak]

Hummingbird migration is in full swing and you may have a few transients refueling on your feeders.
However, hummers are not the only feeder guests. Wasps, ants, and alike take their share and over time I have seen feeders starting to drip and loos fluid that way.

Ulli

PS Not sure where you got the 10 calories a day number. There is at least a k missing .......

Thanks Eric and Ulli.

Migration could explain the increased number of birds. I don't think insects can explain the sugar water consumption though, because all of the feeders are attached to ant guards, and there are bee guards on every feeding port.

BTW, one source for the 10 calories per day figure is here: http://www.learner.org/jnorth/tm/humm/EnergyTorpor.html. And you are right; it should be "Calories."

[Eric Weaver]

I used grease on the feeder pole to keep the ants away. Also worked for the squirrels.

[Ulli Hoeger]

To be a bit more specific,

10 calories are nothing, not even enough to sustain a hummingbird in torpor, which is by the way a hibernation like state with ultra-low metabolism, i.e. energy consumption.

With the missing k I was referring to the more likely number of 10kcal, i.e. 10.000 calories.
This would be closer to a published number for the daily energy use of normally active Anna's hummingbirds with 32kJ/day (~8kcal/day), migratory birds may easily exceed this number. Always good for some confusion is the fact that Calories is used to describe kcal (70 Calories = 70kcalories = 70000 calories), good to know when reading nutritional information on food labels.

An alternative over the thumb way to guestimate hummer numbers visiting your feeders is to assume that an individual has to consume 2.5 -3 times its body weight in nectar per day, i.e. ~10ml of nectar/sugar water a day for a ruby-throated hummer. A liter of feeder solution would fuel 100 hummers for a day, if there are no other consumers (insects etc) or losses (evaporation, dripping)...

Ulli

Thanks Eric and Ulli.

Migration could explain the increased number of birds. I don't think insects can explain the sugar water consumption though, because all of the feeders are attached to ant guards, and there are bee guards on every feeding port.

BTW, one source for the 10 calories per day figure is here: http://www.learner.org/jnorth/tm/humm/EnergyTorpor.html. And you are right; it should be "Calories."

[Norm Dulak]

To be a bit more specific,

10 calories are nothing, not even enough to sustain a hummingbird in torpor, which is by the way a hibernation like state with ultra-low metabolism, i.e. energy consumption.

With the missing k I was referring to the more likely number of 10kcal, i.e. 10.000 calories.
This would be closer to a published number for the daily energy use of normally active Anna's hummingbirds with 32kJ/day (~8kcal/day), migratory birds may easily exceed this number. Always good for some confusion is the fact that Calories is used to describe kcal (70 Calories = 70kcalories = 70000 calories), good to know when reading nutritional information on food labels.

An alternative over the thumb way to guestimate hummer numbers visiting your feeders is to assume that an individual has to consume 2.5 -3 times its body weight in nectar per day, i.e. ~10ml of nectar/sugar water a day for a ruby-throated hummer. A liter of feeder solution would fuel 100 hummers for a day, if there are no other consumers (insects etc) or losses (evaporation, dripping)...

Ulli

Agree. That's why I corrected the spelling of the word Calories above to begin with an upper case C. I goofed on the original. Thanks for pointing that out.