Hummingbirds are known for their incredible flight abilities, their vibrant colors, and their propensity for drinking nectar. But do these tiny birds also possess good memories? In this article, we’ll explore what research has revealed about hummingbird memory and cognition.
Basic hummingbird facts
Before diving into hummingbird memory specifically, let’s review some key facts about these birds:
- There are over 300 species of hummingbird.
- They are found throughout the Americas, from Alaska to Chile.
- They are the smallest birds in the world, ranging from 2 inches to 8 inches long.
- Their rapid wing beats allow some species to hover and fly backwards.
- They have the highest metabolism of all animals due to the energy required for flight.
- They eat nectar, tree sap, insects and spiders.
- Most species are solitary and territorial.
- They have excellent vision, hearing and sense of smell.
Spatial memory
Hummingbirds rely heavily on nectar as their main food source. Nectar-producing flowers are abundant in some areas and scarce in others across the hummingbird’s territory. Remembering the locations of nectar-rich flowers and food sources is critical to their survival.
Researchers have performed experiments demonstrating that hummingbirds have excellent spatial memory and use it to keep track of locations. In one study published in Proceedings of the Royal Society B, scientists captured and released Anna’s hummingbirds at random locations far from their territories and feeding sites. The birds were able to orient themselves and fly directly back to their territories, indicating they could remember spatial locations even when displaced a long distance.
Other experiments have shown hummingbirds remember the locations of artificial feeders refilled with nectar daily. When researchers moved the feeder a short distance, the hummingbird would search for it in its original location before finding it in the new spot. This suggests the birds utilize spatial memory to remember reliable food sources.
Short-term memory
In addition to spatial memory, hummingbirds appear to have a strong short-term memory used for remembering flower locations on a much smaller scale. As they feed, hummingbirds associate certain flowers with the presence or absence of nectar. Within a day, they are able to remember which flowers they have already emptied, avoiding those and going directly to flowers that still contain nectar.
Researchers tested this short-term memory by capturing hummingbirds and releasing them in a screened enclosure containing eight artificial flowers. Four flowers were full of nectar and four were empty. The hummingbirds learned to feed from the full flowers and leave the empty ones. Even if the researchers rotated the array, the hummingbirds remembered which specific flowers had nectar over a period of a few hours.
This ability likely helps hummingbirds maximize their nectar intake efficiently. By remembering recently-visited flowers, they don’t waste energy revisiting flowers without nectar. Their short-term memory persists long enough to allow them to continue foraging among other flowers and return later after flowers have refilled.
Long-term memory
Hummingbirds also appear capable of forming long-lasting memories that allow them to recognize familiar locations, objects and people. When a reliable nectar feeder is available over weeks and months in the same location, hummingbirds will remember it and return to it regularly, even after long periods away.
Researchers discovered that hummingbirds can identify specific individuals as well. In experiments where one scientist consistently provided sugar water and another consistently provided plain water, the hummingbirds learned to approach the “sweet scientist” for a meal. The birds remembered which person to visit even after a month away.
Migration and memory
The long migrations made by some hummingbird species provide further evidence for their impressive long-term memory abilities. For example, the ruby-throated hummingbird migrates up to 5,000 miles between its breeding grounds in the United States and Canada and its winter habitat in Mexico and Central America.
These tiny birds find their way back to the exact same nesting sites and feeding locations year after year, even though they may only spend a few months there. Their ability to encode complex memories of locations must help guide them through these incredible migrations covering thousands of miles.
Brain structures and memory
Hummingbirds have very large brains relative to their diminutive body size. Their exceptional memory abilities are linked to the hyperdevelopment of specific neural structures, including:
- An enlarged hippocampus, which plays a critical role in learning, memory and spatial mapping.
- A larger nidopallium, associated with storing visual information.
- A larger mesopallium, linked to higher-order sensory processing and memory.
Some scientists hypothesize that hummingbirds evolved these enhanced neural areas due to the demands of tracking flower locations across wide territories and navigating long migrations.
Comparisons with other birds
Many bird species make impressive migrations and must likewise recall locations critical to their survival. How does hummingbird memory compare with other migratory birds?
In some ways, hummingbird memory excels. Hummingbirds outperform pigeons, black-capped chickadees and honeybees in short-term memory tasks involving tracking locations of emptied artificial flowers. However, when it comes to longer-term tests, hummingbird memory may be surpassed by that of food-storing songbirds like Clark’s nutcrackers, who can remember thousands of cache locations over months.
Overall, hummingbird memory seems specialized for shorter time spans, enabling them to effectively feed, navigate and survive in the moment. Food-storing birds may invest more brainpower in long-term planning due to the demands of retrieving hidden food caches.
Conclusion
Research to date clearly demonstrates that hummingbirds have excellent memory capabilities well-suited to their lifestyles. Their enlarged brain structures devoted to memory allow them to recall flower locations, feeding sites, migration routes and other spatial information critical to finding food. While their memory may be focused on shorter time spans compared to other birds, hummingbirds possess robust spatial, short-term and long-term memory that aids their survival.
