Hummingbirds are remarkable little birds that have evolved to feed on the nectar from flowers as their main food source. Their long slender beaks and tongues are perfectly adapted for accessing nectar from even the deepest flowers. Hummingbirds need a lot of energy to power their fast metabolisms and rapid wing beats, so they consume up to half their body weight in nectar each day. This reliance on nectar makes hummingbirds very sensitive to any changes or contaminants in their food source. One common contaminant that hummingbirds may encounter is ants, which also feed on flower nectar. So will hummingbirds reject nectar if ants have gotten into it first? Or are they willing to share with these tiny invaders? In this article, we’ll examine the evidence behind hummingbird feeding behavior when ants are present in nectar.
Do Hummingbirds Avoid Flowers with Ants?
Some key research indicates that hummingbirds do their best to avoid feeding from flowers that have ants present. One study published in the journal Biotropica observed hummingbird behavior around flowers that did or did not have ants near the nectaries. The researchers found that hummingbirds visually inspected flowers before feeding and avoided those with ants about 75% of the time. Other observations of broad-tailed hummingbirds showed that they rejected flowers after seeing or contacting ants 70% of the time. So in general, hummingbirds appear able to recognize when ants occupy a flower and they will seek out ant-free flowers to avoid this nuisance. However, sometimes ants go undetected or hummingbirds have no other option but to feed from an ant-occupied flower. What happens in these cases when hummingbirds and ants encounter each other at nectar sources?
How Do Ants Affect Nectar Quality?
Ants are primarily interested in nectar as an energy source and will readily consume flower nectar through their straw-like mouthparts. Nectar is mostly composed of three sugars — sucrose, glucose, and fructose — in water solution. Ants’ digestive systems break down these complex sugars into simpler forms they can metabolize. This process degrades the nutritional quality of nectar for hummingbirds by lowering sugar concentrations. Researchers have quantified drops in sucrose concentrations when ants feed on nectar compared to ant-free flowers. The greater the number of ants at a flower, the more diluted and degraded the nectar became. Not only do ants reduce quantity, but their presence can introduce microbes that spoil nectar as well. Yeasts and bacteria brought by ants can rapidly trigger fermentation and decay of nectar sugars. So when hummingbirds do feed from ant-patrolled flowers, they ingest nectar of lower quality and potential toxicity compared to ant-free sources.
How do Hummingbirds Respond to Ant Contaminated Nectar?
Even if they must share flowers with ants, hummingbirds have ways to minimize their exposure to degraded nectar. One strategy is to selectively pierce the base of the flower where ants are less likely to penetrate. Hummingbirds can also use their bills to scrape ants off flowers or evict them from nectaries. This behavior of physically displacing ants is called anting. If ants are occupying the entire flower, hummingbirds may opt to feed at the youngest flowers on a plant that are less likely to have ants. Another approach is to rapidly expel droplets of ant-contaminated nectar from their tongues after sensing its poor quality. Researchers found the time hummingbirds spent licking nectar was substantially reduced when ants were present compared to ant-free flowers. By minimizing intake from ant-visited flowers, hummingbirds reduce their consumption of watered-down and potentially toxic nectar. This helps compensate for the lower nutritional value but does not completely eliminate the impacts of ant contamination.
Effects of Ants on Hummingbird Health and Foraging
The consequences of sharing nectar sources with ants may have significant impacts on hummingbird energetics and survival. As experts in high-speed energy consumption, hummingbirds need consistent, high-quality nectar to maintain their metabolisms. Studies have shown broad-tailed hummingbird bodies contained lower sugar levels after feeding extensively on ant-visited flowers compared to ant-free flowers. This drop in sugar intake led to reduced body mass, indicating the birds struggled to meet their nutritional needs despite compensatory feeding behaviors. Researchers have observed hummingbirds visiting up to 30% more flowers when ant populations spike in an area. More time and effort spent foraging to find adequate nutrition mean less time devoted to rest and recuperation. During demanding life stages like molting or migration, poor nutrition because of ants could be especially detrimental to hummingbird health and reproduction. There is also evidence that territorial hummingbirds become more aggressive against intruders when ants diminish the nectar supply in their territory. Competition for limited food resources may lead to more intense guarding of remaining ant-free flowers.
Conclusion
The consensus from multiple field observations and feeding studies is that hummingbirds prefer not to share flower nectar with ants. Though they have evolved adaptations to detect and avoid nectar-robbing ants, hummingbirds cannot always escape ant contamination. When ants go unnoticed or alternatives are unavailable, hummingbirds turn to strategies like anting, selective feeding, and rapid expulsion of low-quality nectar. But frequent ant exposure still carries health costs for hummingbirds, including reduced energy intake and increased foraging time. Persistent ant infestations in habitats require hummingbirds to visit more flowers for adequate nutrition to the detriment of their energy budgets. While hummingbirds demonstrate resilience against ant competitors, the ideal scenario is for hummingbirds to have access to high volumes of ant-free nectar. This ensures they can meet the extremely high metabolic demands that characterize these captivating creatures. So in their best interest, hummingbirds would prefer not to share nectar with ants!
| Research Findings | Hummingbird Response When Ants Present |
|---|---|
| Hummingbirds visually inspect flowers and avoid feeding on flowers with ants 70-75% of the time | Preferentially seek out and feed from ant-free flower sources first |
| Ant consumption degrades nectar quality by lowering sugar concentrations | Selectively pierce flower bases away from ants; scrape ants off flowers |
| Ants can introduce microbial contamination leading to nectar fermentation | Minimize feeding time and rapidly expel ant-contaminated nectar |
| Feeding on ant-visited flowers leads to reduced energy intake and body condition | Increase foraging effort and flower visits to find adequate nutrition |
| Territorial hummingbirds become more aggressive when ants diminish nectar supply | Guard ant-free flowers more intensely as food resources dwindle |
Key Takeaways
Hummingbirds have evolved behaviors to detect and avoid flowers occupied by ants.
When forced to share flowers, hummingbirds minimize contact and ingestion of degraded nectar.
Frequent ant exposure results in lower energy intake and requires increased foraging time.
Hummingbirds prefer ant-free flower nectar but can adapt when ants contaminate limited food supplies.
Hummingbirds rely on nutrient-rich nectar to power their high metabolisms and impressive flight abilities. Ant contamination reduces nectar quality, forcing hummingbirds to adjust their foraging strategies and accept lower energy reserves. While hummingbird adaptations allow them to cope with ants in nectar when necessary, these remarkable birds thrive best on a high-volume, ant-free nectar supply. Ensuring hummingbird habitats offer abundant clean nectar enhances the health and productivity of these captivating creatures. With access to quality food sources, hummingbirds can achieve the peak performance we marvel at when watching them hover and dart from flower to flower.
