Hummingbirds are amazing little creatures that have captured the fascination of people for centuries. One of the most common questions people have about hummingbirds is whether they prefer cold or warm nectar. In this article, we’ll explore the latest scientific research to find the answer.
Nectar Temperature Preferences
Several studies have tested the nectar temperature preferences of hummingbirds in either lab settings or field observations. The results show some differences depending on geography and species, but the overall consensus is that hummingbirds prefer warm nectar.
A study in Canada tested the nectar preferences of Ruby-throated Hummingbirds at feeders with nectar temperatures ranging from 10°C to 40°C. The hummingbirds showed the strongest preference for nectar between 30°C and 40°C (86°F to 104°F). They avoided the colder nectar temperatures when warmer nectar was available.
Another study in the highlands of Mexico examined Mountainous Woodstar hummingbirds feeding from flowers along an elevation gradient with temperatures ranging from 23°C to 29°C (74°F to 84°F). The hummingbirds preferred the warmer flowers at lower elevations and would actively avoid flowers at cooler temperatures.
Research in South America on Buff-tailed Coronets similarly found they preferred warmer nectar. A lab experiment offered nectar at 10°C, 20°C, and 35°C (50°F, 68°F, and 95°F). The birds chose the 35°C nectar significantly more than the cooler temperatures.
Across these studies in North America and South America, wild hummingbirds show a strong inclination for warmer nectar temperatures.
Why Hummingbirds Choose Warm Nectar
There are a few key reasons why hummingbirds prefer warmer nectar:
- Warm nectar has lower viscosity or thickness, making it easier and more energy efficient to drink.
- Cooler nectar may contain higher sugar concentrations, which could overwhelm their taste preferences.
- Warm nectar speeds up their metabolisms, providing quick energy.
- Colder temperatures, especially at night, increase their risk of torpor or hibernation.
The viscosity of nectar is a key factor. Hummingbirds have specially adapted tongues and beaks to slurp up nectar. Cold temperatures thicken nectar, making it harder to drink. The preference for warmer temperatures allows hummingbirds to get the maximum nutrition with minimal effort.
Higher sugar concentrations in colder nectar may also deter hummingbirds. As a flower’s nectar cools overnight, some water may evaporate while the sugar content remains. This can alter the taste in a way that hummingbirds dislike based on their evolutionary adaptations.
The metabolic boost from warm nectar provides quick energy for their rapid heartbeats and high activity levels. Cooler nectar forces their metabolism to work harder pumping energy through their system.
Finally, cold exposure threatens hummingbirds with torpor or a light hibernation. Their tiny bodies lose heat rapidly at night. Warm nectar helps counteract this to keep their metabolism humming.
Do All Hummingbirds Avoid Cold Nectar?
Most research shows an overall preference among hummingbirds for warmer nectar. However, a couple of studies indicate that some species can adapt to colder conditions.
Anna’s Hummingbirds in California showed flexibility in their nectar choices across different times of day. In the morning, they preferred warmer nectar around 30°C (86°F). By late afternoon, they switched to favor cooler 21°C (70°F) nectar, perhaps to aid heat dissipation.
A study of Anna’s and Rufous Hummingbirds found they could survive short-term cold exposure down to 5°C (41°F) at night, avoiding complete torpor. This suggests some physiological adaptations to handle the cold if needed.
So while most hummingbirds strongly prefer warm nectar, a handful of species may have some inbuilt resilience to cold temperatures.
Impact of Climate Change
Climate change creates a complicated scenario for hummingbirds and nectar temperatures. In some cases, warming temperatures may be beneficial. But increased climate chaos could also disrupt the availability of food sources.
Higher daily temperatures may ensure more hours of warmer nectar. However, it could also lead to nectar overheating by the afternoon in very hot conditions. This heat stress could deter hummingbirds from feeding during parts of the day.
At the same time, increased climate variability may make it harder for hummingbirds to adapt. More frequent extreme weather shifts such as heatwaves or unusual cold snaps could create nectar conditions they are unprepared for.
The timing of seasonal flower blooming and hummingbird migration is also coming under threat. Earlier springs and later autumns due to climate change could lead to mismatches between peak flowering and peak migration. This limits food availability at key occasions in the yearly cycle.
Climate impacts create a complex picture, but generally warmer average conditions will increase hours of their preferred higher nectar temperatures. However, the overall disruption to natural cycles and greater variability may undermine these potential benefits.
Helping Hummingbirds With Nectar Feeders
For people who want to help hummingbirds in their yards, providing nectar feeders is an excellent step. Keeping the nectar warm helps attract and nourish hummingbirds.
Tips for Warm Nectar
- Make nectar early in the day or even the night before so it starts warm.
- Store unused nectar in the refrigerator to slow fermentation but do not put cold nectar straight into feeders.
- Set feeders in sunlight which helps maintain warmth, but avoid hot direct sunlight.
- Choose darker colored feeders which absorb more heat. Lighter colored feeders stay cooler.
- Use small volumes of nectar so each refill starts fresh and warm.
With these tips, you can provide an appealing nectar buffet for local hummingbirds. Just remember to clean feeders regularly to keep the nectar fresh and healthy.
Ideal Nectar Temperature Range
Based on the scientific research, aim for a nectar temperature of 85-95°F (29-35°C) in your feeders during active hummingbird hours. This warmth helps the nectar flow and boosts hummingbird metabolism.
Check feeder warmth periodically with a thermometer or by feel on the back of your hand. Refill with fresh warm nectar or move to a warmer spot if the temperature drops below 80°F (27°C).
With some attention and planning, you can replicate the warmer flower nectar that hummingbirds naturally prefer.
The Bottom Line
Extensive research on wild hummingbirds shows they are drawn to warmer nectar temperatures. This preference exists across diverse species in North America and South America. Warmer nectar likely offers easier drinking, faster energy, and reduced risk of cold stress for these tiny birds.
While most hummingbirds prefer warmth, some species demonstrate flexibility to handle temporary cold exposure. There are also complex impacts from climate change that could either extend favorable conditions or increase variability.
People who want to help hummingbirds can make a difference by keeping feeder nectar within an ideal 85-95°F (29-35°C) range. With some planning and awareness, we can provide a convenient nectar source that caters to hummingbirds’ natural taste for warmth.
