Summer in the United States, with its glorious sunshine and vibrant wildlife, is a prime time for observing the dazzling aerial acrobatics of hummingbirds at our feeders. However, the season’s soaring temperatures can pose a hidden challenge: keeping the life-sustaining nectar fresh and safe for these tiny, energetic visitors. Neglecting to change the sugary solution frequently enough in the summer heat can lead to fermentation, mold growth, and the proliferation of harmful bacteria – a potentially dangerous scenario for the very creatures we aim to help. This article answers the crucial question every conscientious hummingbird enthusiast in the U.S. faces: How often should you really be changing your hummingbird nectar during the summer months to ensure a healthy and thriving feeding station? The answer is quite straightforward, and there are some very good scientific reasons for it.   

Spoilage

To keep the hummingbirds healthy and happy, you should change the nectar in your feeder every 1 to 2 days during hot weather (above 70°F). In cooler weather, you can change it every 3 to 5 days. 

Mold and bacteria thrive in hummingbird feeders due to a combination of factors. Firstly, the sugar-rich environment is a perfect food source for many types of mold and bacteria. Sugar provides the necessary energy for these microorganisms to grow and multiply rapidly. Mold and bacteria also need moisture to flourish. The nectar solution provides a constant supply of water. This is bad enough but in the summer months in the U.S., the temperatures can rise significantly, particularly if the feeder is in direct sunlight. Warmth accelerates the growth rate of these microorganisms. The sugar in the water can also ferment in the heat.   

Exposure to air and the environment is inevitable, even with precautions, and airborne mold spores and bacteria can land on the feeder and in the nectar, especially when hummingbirds feed. Insects can also introduce microbes. Even trace amounts of saliva or food particles left by hummingbirds can serve as additional nutrients for microbial growth.

As well as the very nature of sugar itself and the warmth of the summer, if feeders are not cleaned thoroughly and frequently, residual mold and bacteria can quickly contaminate fresh nectar. This can lead to some serious consequences for hummingbirds. Fungal infections can be caused by mold, particularly Candida. These can infect a hummingbird’s tongue and throat, causing swelling and making it difficult or impossible for them to feed. Aspergillosis is another fungal infection that can affect their gastrointestinal tract. These infections can be fatal. Bacteria like Salmonella can contaminate the nectar and cause gastrointestinal problems, hindering nutrient absorption and potentially leading to death. 

While not directly a result of mold or bacteria in the nectar, unclean feeders can facilitate the spread of viruses like Avian Poxvirus, which causes tumor-like growths on the beak and can be transmitted between birds at a contaminated feeder. Some studies suggest that while the majority of microbes found in feeders may not be harmful, the risk of pathogenic growth is still present, especially if feeders are not maintained properly. Therefore, changing of nectar along with regular and thorough cleaning is crucial to protect the health of hummingbirds.

Cleanliness is key

You clean your hummingbird feeder to protect the health and well-being of the hummingbirds that rely on it as a food source. As we discussed, the sugary nectar is a breeding ground for harmful mold and bacteria. These microorganisms can cause infections and even be fatal to these tiny, delicate birds. Regular cleaning removes these contaminants, ensuring the nectar you provide is safe for them to consume.   

Here’s a step-by-step guide on how to clean your hummingbird feeder.

Frequency

Clean your feeder every time you change the nectar (every 1-2 days in hot weather, every 3-5 days in cooler weather). A more thorough cleaning should be done at least once a week.

Materials

• Hot tap water
• Dish soap (mild)   
• Bottle brush or pipe cleaners (to reach all parts of the feeder, especially small openings and crevices)   
• Small bowl or container
• Clean cloths or paper towels
• Optional: White vinegar or a diluted bleach solution (see instructions below for proper use)

Steps for Cleaning

Pour out any remaining nectar. Don’t just top it off, as this leaves old nectar at the bottom where bacteria and mold can thrive. Disassemble the feeder as much as possible and then rinse all parts of the feeder (the bottle, feeding ports, base, and any other components) under hot running water to remove loose debris and sugar residue. In a bowl or container, mix a small amount of mild dish soap with hot water.

Use your bottle brush and pipe cleaners to scrub all surfaces of each part of the feeder, paying close attention to the feeding ports, the inside of the bottle, and any areas where nectar might accumulate. Mold often appears as black or dark spots. Lastly, rinse all parts thoroughly under hot running water until all traces of soap are gone. Soap residue can be harmful to hummingbirds.   

Disinfect 

Use a disinfection solution weekly or if mold is present. There are two main options for disinfection. 

• Method 1 – Mix 1 part unscented household bleach with 9 parts water. Soak all parts of the feeder in this solution for about 10-15 minutes. Rinse extremely well under cold running water for several minutes until you can no longer smell any bleach. Bleach residue is toxic to hummingbirds. 
• Method 2 – Mix 1 part white vinegar with 4 parts hot water. Soak all parts of the feeder in this solution for at least 30 minutes to an hour. Vinegar is a natural disinfectant and is safe for hummingbirds as long as it’s rinsed off thoroughly. Rinse all parts very well under cold running water.

Dry Completely

Allow all parts of the feeder to air dry completely before refilling with fresh nectar. This helps prevent further microbial growth. You can also use a clean cloth or paper towel to dry the exterior.   

Reassemble and Refill

Once completely dry, reassemble the feeder and fill it with fresh, properly prepared nectar (1 part white table sugar to 4 parts water, boiled and cooled).

Important Considerations

Don’t use harsh chemicals, abrasive cleaners, or scouring pads, as these can scratch the feeder and make it harder to clean in the future. Residue can also be harmful.

Pay special attention to cleaning the feeding ports, as this is where hummingbirds directly access the nectar and where mold and bacteria can easily accumulate.   

Check your feeder regularly for any signs of mold growth or cloudiness in the nectar, even between cleanings. If you see anything suspicious, empty, clean, and refill the feeder immediately.

By following these cleaning steps consistently, you’ll be providing a safe and healthy feeding environment for the beautiful hummingbirds in your area!

Cloudy nectar

Cloudy nectar in your hummingbird feeder is a clear sign that the nectar is spoiling and is no longer safe for the hummingbirds to drink. The cloudiness is usually caused by the growth of bacteria, mold, or yeast in the sugar water solution. These microorganisms thrive in a sugary environment, especially in warm temperatures. Also, the sugar in the water can begin to ferment, further contributing to the cloudiness and potentially producing harmful byproducts. It is absolutely NOT okay to leave cloudy nectar in your hummingbird feeder.

As we’ve discussed, spoiled nectar can lead to serious and even fatal infections in hummingbirds. Spoiled nectar also loses its nutritional value and may even deter hummingbirds from feeding altogether. If you see cloudy nectar, empty the feeder immediately. Then clean the feeder thoroughly as outlined above and refill with fresh nectar. Only fill the feeder with an amount of nectar that the hummingbirds are likely to consume before it spoils. If possible, position your feeder in a shady spot to help keep the nectar cooler and slow down spoilage.   

In short, cloudy nectar is a warning sign. Take immediate action to clean your feeder and provide fresh food to keep your hummingbird visitors healthy!

Recipe

Here’s the recipe for hummingbird nectar and what you should avoid doing.

• 1 part refined white table sugar
• 4 parts water   

Combine the sugar and water in a clean saucepan. Heat the mixture over medium heat and stir until the sugar is completely dissolved. You don’t need to boil it, but heating helps the sugar dissolve more easily and can help to sterilize the solution. Allow the nectar to cool completely to room temperature before filling your feeder. Warm nectar can promote faster spoilage and could potentially harm the birds. Store any leftover nectar in an airtight container in the refrigerator for up to one week. Make sure it’s at room temperature before refilling your feeder.

There are some very important things you should NOT do. Firstly, never use honey as it promotes the growth of a dangerous fungus that can be fatal to hummingbirds. Also, never use artificial sweeteners. Hummingbirds need the calories from sugar for energy. Artificial sweeteners provide no nutritional value. Always use plain white granulated sugar. Never use brown sugar, raw sugar, or powdered sugar, as these contain molasses or other additives that can be harmful to hummingbirds due to their iron content or other ingredients like cornstarch. You should also never add fruit juice or other sugary drinks: These don’t provide the correct type of sugar concentration that hummingbirds need and can spoil quickly.

No dye

We know hummingbirds love the color red, but you should never add red dye or any other food coloring. Most hummingbird feeders are designed with red parts (feeding ports, bases, or decorations) specifically to attract hummingbirds. They have a natural visual preference for red flowers, so the feeder itself serves as the attractant. The color in the nectar doesn’t add any extra benefit for attracting them. In addition, the nectar that hummingbirds find in flowers is naturally clear. Adding red dye is an artificial addition that doesn’t mimic their natural food source. There is also concern that the artificial chemicals in dyes could put unnecessary stress on the hummingbirds’ kidneys and liver as they try to process these foreign substances.   

Although definitive, peer-reviewed scientific studies directly linking red dye to specific health problems in hummingbirds are limited, there is enough concerning evidence to warrant caution. Studies on laboratory animals have shown that some red dyes, like Red Dye #40 (Allura Red AC), a common ingredient in red food coloring, can be carcinogenic, cause DNA damage, and be linked to reproductive issues and tumors at high doses. While hummingbirds are different, their small size and high metabolism mean they could potentially ingest a significant amount of dye relative to their body weight if the nectar is consistently colored red.

To summarise, there is no benefit to adding red dye, and there is a potential risk of harm. Why take that chance when it’s so easy to make safe and effective clear nectar? Let the red parts of your feeder do the job of attracting these beautiful birds, and keep the food itself as natural as possible.   

Storage

Always store any leftover hummingbird nectar in an airtight container in the refrigerator. This significantly slows down the growth of mold, bacteria, and yeast. Use clean, airtight containers to prevent contamination and evaporation. Glass or food-grade plastic containers with tight-fitting lids work well. It is also a good idea to label the container with the date you made the nectar. This helps you keep track of how long it has been stored. Generally, refrigerated hummingbird nectar is best used within one week. Even in the refrigerator, spoilage can eventually occur. If you notice any cloudiness or mold growth, discard it immediately, even if it’s within the week.   

Before refilling your feeder, allow the refrigerated nectar to come to room temperature. While there’s no evidence that cold nectar ‘shocks’ hummingbirds, offering them lukewarm nectar is likely more natural and comfortable for them. To minimize waste, consider making smaller batches of nectar that your local hummingbirds are likely to consume within a few days.

Final Thoughts

Offering nectar in feeders to hummingbirds is a wonderful thing to do. You get to support these wonderful creatures and get to watch them at the same time. It is a responsibility, however. There is no point in committing to having feeders unless you are prepared to do it correctly. By following our simple guidelines, you will ensure that the birds get the maximum benefit from your feeders and you get the satisfaction of having these gems visit you time and again. Good luck!