Hummingbid water ratio

[Adrienne]

Hello everyone, 

So there is a debate on NextDoor about the proper water to sugar ratio and I don't want to spread misinformation. Are scientists divided on the issue too? I'm being accused of being selfish and misleading people (welcome to social media), so just asking this group which I understand has a few experts in its distribution list. Thanks!

Adrienne

I've included below three sources of info I found:

1. https://www.thespruce.com/hummingbird-nectar-recipe-386573

2. https://thegrownetwork.com/hummingbird-sugar-water-ratio/

3.  [December 2021 email from Mid-Valley Nature group discussion]

The extended weather forecast shows unusually cold temperatures and snow between Christmas and New Year's Day.  The various weather models are currently saying that lows could be in the single digits to the mid-teens, and with multiple days staying below freezing, it will probably be colder weather than we've had since December 2013.  We thought we'd put together some cold weather tips for those who feed birds.

• Switch hummingbird nectar to a 3:1 water:granulated white sugar solution.  The freezing point will be depressed so it will stay liquid at slightly colder temperatures than a 4:1 solution, and it contains more calories per volume.  (See below for an explanation of the benefits and safety of a 3:1 solution from hummingbird expert and field guide author Sheri Williamson.)*
  
  
• Keep nectar thawed from morning twilight to evening twilight.  A short strand of the old-style incandescent Christmas lights wadded up and attached to the bottom of the feeder usually produce enough heat to keep nectar from freezing on cold days (LED lights won't work), although the feeders may still have to be brought in overnight.  We've used a "heat rock" designed for reptile cages, and that was effective also.  There are also heated feeders available from Hummers Heated Delight in Albany, and people have come up with other creative ways to keep it thawed.  The northern expansion of the Anna's Hummingbird range is new and closely associated with humans, and research shows that they are at least partially dependent on supplementary nectar-feeding here.
  
  
• Some small birds, including chickadees, bluebirds and wrens will roost in cavities/nest boxes.  If you have nest boxes and haven't cleaned out old nests, check to see if the nest material has gotten wet with all the rain we've had.  If it's wet or dirty, you can remove it and fill the box about halfway with fresh, dry insulating material such as straw, dry leaves, pine needles, wood shavings, feathers or dry moss or lichens.  Things to avoid include dryer lint, cotton batting and polyester fiberfill/stuffing.   Cover ventilation slots (cardboard and thumbtacks work), or stuff the vents with the insulating materials listed above, or use foam weather stripping.
  
  
• If you can, offer fresh water in your birdbath at least twice a day because birds need to drink, especially seed-eaters.  They can eat snow, but it costs them additional energy to do this.  They also need to bathe to keep up the insulating capacity of their plumage.  You can pour warm water (105F) into the birdbath and it will take quite a while to freeze.
  
  
• Pine Siskins are still suffering from salmonellosis and need seed feeders to be cleaned as often as possible.  The primary source of disease is when siskins eat fallen seed and droppings that mingle beneath feeders, so minimizing that is the best way to reduce transmission.  The stress of cold weather may make them more vulnerable.

Lisa Millbank and Don Boucher

*From Sheri Williamson, author of the Peterson Field Guide to Hummingbirds of North America and Attracting and Feeding Hummingbirds:

"Some hummingbird experts do (or did) insist on a feeder solution no stronger than 4:1, but I've never been a member of that camp. On page 40 of Attracting and Feeding you'll find that I recommend a solution of three to five parts water to one part sugar - a pretty wide range. Hummingbird-pollinated flowers produce nectar that ranges in sugar content from as weak as 10:1 to as strong as 1:1.
Both of the extremes are rare, and the average sugar content is close to 3:1.
Studies of the birds' physiology suggest that solutions stronger than 3:1 may not provide sufficient water in extremely hot, dry conditions and that solutions weaker than 4:1 may not provide enough sugar for the birds to maintain their body weight when the weather is cold (stronger solutions also freeze at lower temperatures, which is very useful for people lucky enough to host hummingbirds year round). A 5:1 solution can be useful in discouraging bees or helping the birds through extreme heat and drought.
When I wrote Attracting and Feeding eight years ago, I was deliberately conservative in my recommendations to avoid upsetting a handful of my colleagues in the hummingbird community who were adamantly opposed to solutions stronger than 4:1. Since then most of them have changed their minds, thanks in large part to the article that begins on page 7 of this issue of the Louisiana Ornithological Society News
I now feed 3:1 most of the year, except during the very hot, dry days of late spring and early summer, and I do think it helps the southbound migrants and overwintering birds. Using a slightly stronger solution may not be as important to your feeding strategy with all the good natural food you're providing, but it isn't going to do the birds any harm."

[Lisa Millbank]

Yes, we've seen hummingbird nectar ratio discussions get surprisingly heated on social media.  This is probably because people truly care about hummingbirds and quite understandably, fear doing anything that could harm them.  The 4:1 ratio has been the standard for a very long time, and there were even some misconceptions that persisted until fairly recently about how hummingbirds' tongues work, which caused people to worry about increasing the viscosity of nectar solutions.  And, of course, even when everyone's intentions are good, social media discussions often end up not being particularly nuanced, well-researched or carefully thought out.

One factor that limits hummingbirds' calorie intake in cold weather is the rate at which their kidneys can excrete excess water.  Hummingbirds' kidneys are extremely efficient at getting rid of the excessive water intake of their diet, but when calorie requirements are very high, it is more difficult for them to meet their energy needs with weaker nectar solutions.  An interesting article was published by Arizona State University about research done on hummingbirds and sunbirds.

Hummingbird field guide author and expert Sheri Williamson has written,

"The difference to the birds is that a 1:3 ratio allows them to feed more efficiently, which is important when they're under stress from migration or cold weather. When competition is high during the peak of migration, a slightly stronger solution allows them to get the calories they need with fewer and/or shorter trips to the feeder, allowing energy that would have been expended on fending off rivals to be stored as fat to fuel migration. In cold weather, a slightly stronger solution allows them to meet their increased energy needs without taking in as much cold water that has to be warmed to body temperature, filtered through the kidneys, and excreted as urine (taking some of the body's precious warmth with it)."

Don Powers, hummingbird researcher and professor of biology at George Fox University, had this to say on an OBOL (statewide birding list) thread:

"As a physiologist who has studied hummers for 40+ years I agree with Sheri’s assessment of sugar concentration for feeder solutions.  Frankly, I get so many people who ask me why their neighbors have hummers and they do not.  My typical response is that most people make their feeder solutions 4:1, but if they start making theirs 3:1 they will no longer be short of birds.  Works most of the time.  The other advantage of a 3:1 solution is that it will depress the freezing point of the solution a bit.  

An extended discussion about nectar solutions from Don Powers is here.

Hummingbirds' tongues were once thought to work through capillary action, but now are known to have a much more complex structure that captures nectar with moving plates as the tongue is drawn back into the oral cavity.  It was thought that a 4:1 sugar solution was of the ideal viscosity.  However, we now know that many floral nectars that hummingbirds drink without any problem are highly concentrated and more syrupy than the 4:1 solution.  Hummingbirds are quite capable of drinking floral nectar that has been evaporating and concentrating on hot, windy days, or even various concentrations of tree sap flowing from sapsucker wells. 

Both 4:1 and 3:1 sugar solutions fall well within the range of natural floral nectars, although 4:1 is on the lower end of the spectrum.  A 4:1 solution is 20%, by volume, and 3:1 is 25%. Common flowers that people grow for hummingbirds can have concentrations as high as 38%, such as some of the ornamental red sage species that are extremely attractive to hummingbirds. 

The Cornell Lab of Ornithology recommends a 3:1 solution in cold weather, and we haven't been able to find any credible published research that shows that 3:1 solutions cause any problems for hummingbirds.  We've fed a 3:1 solution in winter for years, and often have a dozen or more hummingbirds in the yard, including several individuals we have hand-fed for multiple years.  The bottom line is that both 4:1 and 3:1 nectar solutions are acceptable and safe for hummingbirds, but there are some advantages of 3:1 in cold weather.

Lisa Millbank & Don Boucher

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[Adrienne]

Thank you Lisa so much. Would I have your permission to share this response on NextDoor (and I can omit your name but give credit to Anonymous Mid-Valley Nature Bird Fan, for example?) No pressure, if you prefer I not repost, although this is very valuable fact checked info.

So happy, and reassured! thanks again.

Adrienne

[Jamie S.]

Thanks for the reminder... I was still in the 4:1 camp but Cornell tops all.

Jamie Simmons

Corvallis

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[Lisa Millbank]

Hi Adrienne,

If you're able to post the entire response on NextDoor, that would be fine, and you can include our names.  However, if there's a character limit, we would prefer you link to the message itself (https://groups.google.com/g/mid-valley-nature/c/OKUZ83wxRU0/m/5wBwE_GFAAAJ) so that people can read the whole message.

Lisa

[Adrienne]

Hi Lisa,

Fantastic, will include your names and see what works best on NextDoor.

Thanks!!

Adrienne

The lesson I have thoroughly learnt, and wish to pass on to others, is to know the enduring happiness that the love of a garden gives. Gertrude Jekyll