Quick Answers
There are a few potential reasons why a hummingbird may be hitting your window:
- It sees its reflection in the window and thinks it is another bird in its territory.
- It sees plants or feeders indoors and is trying to get to the nectar.
- The window is positioned near a preferred flight path between feeding locations.
- It gets confused by see-through glass and does not realize it is a barrier.
Some solutions to deter hummingbirds from hitting windows include:
- Placing decals, sun catchers, or other decorations on the outside of the window.
- Closing curtains or blinds in rooms where feeders are visible through glass.
- Moving feeders further away from problematic windows.
- Installing an ultraviolet coating or film on the window.
Why Do Hummingbirds Hit Windows?
Hummingbirds are very territorial creatures and they will defend their feeding grounds aggressively. A male hummingbird will often attack other birds that enter his territory, even battling against his own reflection in windows or mirrors mistaken for an invader. This is likely the most common reason behind hummingbirds hitting windows.
The hummingbird sees his reflection and believes it to be another male hummingbird in his turf. He will then aggressively fly at the window trying to scare off the intruder. The hummingbird does not realize the reflection is himself or that the window is a solid barrier. This is due to a couple factors:
Poor Depth Perception
Hummingbirds have excellent vision for detecting color and movement, but they have relatively poor depth perception compared to other birds. It is hard for them to distinguish that the reflection is not actually another bird farther away. The smooth reflective surface of a window can appear to be an open path they can fly through.
Ultra-Territorial Nature
Hummingbirds are extremely territorial. They will defend a feeding territory spanning approximately a quarter acre. Within this territory, there are often several key nectar sources the hummingbird will regularly patrol. They will aggressively chase away any competitor birds encroaching on their turf.
Due to their small size, hummingbirds are vulnerable to predators. They cannot afford to share food sources that sustain their high metabolism. This causes them to viciously attack anything perceived as a threat, including their own reflection. Battling against window reflections is often just part of their hard-wired territorial behavior.
Frequent Use of Flight Paths
Hummingbirds establish regular flight routes between their favored nectar sources within their territory. These flight paths are used routinely many times a day. Windows that happen to be positioned interfering with well-established flight paths can cause repeated collision incidents.
The hummingbird may not even be provoked by his reflection in this case. He is just habitually following the same path on autopilot without realizing a new obstruction has been introduced. This is especially common with feeders placed too close to windows. The hummingbird will predictably zip back and forth between the feeder and nearby flowers, often smacking right into windows on the way.
Attempting to Reach Food Source
Hummingbirds may also hit windows when attempting to reach a real or perceived food source on the other side of the glass barrier. This happens most frequently when bird feeders or flowering plants are positioned just inside a window.
The hummingbird sees the nectar buffet inside and single-mindedly tries getting to it, not comprehending the invisible wall blocking its path. Likewise, colorful curtains or decor behind windows can appear as impromptu feeders to hungry hummingbirds. The birds then futilely peck and claw at the window as they try fruitlessly to access the nectar within.
Migrating Birds Mistaking Reflections
During migration seasons, transient hummingbirds passing through unfamiliar environments are especially susceptible to window collisions.
A migrating hummingbird seeks temporary shelters with plentiful food between long journeys. They may come across their reflection in a window and mistake it for a competitor guarding a potential pitstop oasis. Not knowing the area, the migrating bird cannot distinguish the reflection from reality and ends up repeatedly diving after the mirage.
This demonstrates why leaving feeders up consistently during migration seasons is so important. Migrating birds rely on these pitstops across vast distances to refuel.
Negative Effects of Hummingbirds Hitting Windows
Window collisions take a major toll on hummingbird populations. As many as a billion birds die annually from striking residential windows in the United States and Canada, according to a 2014 study published in The Condor: Ornithological Applications. Of these, hummingbirds account for somewhere between one to five percent of the casualties based on citizen science data.
The negative impacts include:
Injury and Death
Although they are small, hummingbirds fly fast. It is estimated they can reach flight speeds up to 30 mph. At that velocity, the force generated by a hummingbird head-on collision with a stationary window is enough to cause concussions, internal bleeding, broken wings, ruptured organs, and other life threatening injuries.
Researchers estimate 25-50% of window strike incidents are immediately fatal for smaller bird species. Many injured hummingbirds also die later from internal hemorrhaging or starvation, having lost the ability to feed themselves efficiently.
Bird Size | Percent of Strikes Immediately Lethal |
---|---|
Hummingbird | 25-50% |
Songbird | 25-50% |
Owl | 80% |
Interrupted Feeding
Hummingbirds have the highest metabolism of all birds. To sustain their energy they must feed half their weight in nectar daily, spread across 5-8 feeding periods. That is equivalent to a human eating 200 pounds of food per day!
Any disruption to this frequent nectar intake can have dire effects. Being dazed or injured from a window collision prevents the hummingbird from feeding normally. Blood loss from internal injuries also necessitates higher energy intake for recovery. Without adequate sustenance, the weakened hummingbird can quickly starve.
During migration seasons, window collisions deter hummingbirds from refueling at critical stopover points needed to complete journeys. This can indirectly lead to starvation or force early migration before chicks have fully grown, reducing reproductive success.
Population Declines
The accumulating toll of window casualties causes substantial population declines over time, especially among species already endangered. The Rufous hummingbird for example has decreased by an estimated 2.6% annually for decades, with window collisions likely a primary driver.
Habitat loss from human development also concentrates hummingbirds in residential areas more exposed to window hazards. As their feeding habitats shrink, the relative impact of each window strike fatality increases on a local population level.
Loss of Pollination Services
Hummingbirds are critical pollinators of wildflowers, fruiting plants, and trees. The coevolution of hummingbirds and nectar plants makes them more specialized than other pollinators like bees. Declining hummingbird numbers diminish pollination for many plant species.
This can have ripple effects across ecosystems. Diminished plant propagation impacts food chains up to insects, birds, and mammals. For humans, it affects fruit yields, crop production, forestry, and the availability of wild medicinal plants.
How to Deter Hummingbirds from Hitting Windows
Here are some tips to prevent hummingbirds from colliding with your windows:
Use Decals and Reflective Deterrents
Placing stickers, decals, sun catchers, mylar tape, or other decorations on the exterior of windows can help deter hummingbirds. These break up reflective surfaces and alert hummingbirds that the window is a solid barrier.
Spacing deterrents no more than 2-4 inches apart works best to create visibility from all angles. Vertical rows or a grid pattern across the whole window is ideal.
Deterrents should be placed on the outside of windows since that is the direction hummingbirds approach from. Use high visibility colors like red, orange, and yellow that contrast the surrounding environment.
Keep Feeders Away From Windows
Avoid placing feeders within 3 feet of windows if possible. This can help stop hummingbirds from hitting the window as they fly to and from a feeder.
If a window must be near a feeder location, apply deterrents as a visual cue. For an acute problem window, consider moving the feeder entirely to a different part of the yard.
Limit Reflections in Feeder Rooms
Close curtains, blinds, or drapes in rooms where feeders are visible through windows. Blocking indoor reflections helps prevent attraction and collisions.
Turn off unneeded lights at night when reflections are more pronounced. Use task lighting focused away from problematic windows instead.
Install Ultraviolet Window Films
There are special UV-reflecting films designed for preventing bird collisions. These reflect wavelengths seen by birds but remain mostly transparent to humans. This effectively transforms windows into visible barriers.
If window films are not an option, consider adding bird-safe architectural design elements like overhangs and screens to an affected building. This physically blocks access to glass while maintaining open visibility.
Place Obstacles in Flight Paths
Identify and disrupt key flight routes causing repeated window strikes. This may involve positioning trees, bushes, trellises, or other obstacles to reroute hummingbird traffic away from collision prone zones.
Be mindful not to block access to important nectar sources hummingbirds rely on. The goal is funneling their flight path, not deterring them from a vital feeding area altogether.
Shut Off Problem Windows at Key Times
During peak activity periods when window collisions spike, preemptively shut problematic windows. Early morning, mid-day, and dusk tend to be worst for hummingbird strikes as birds are most active.
This removes the collision hazard temporarily during crucial foraging times. Combined with deterrents and feeder positioning, it can eliminate collisions for vulnerable windows.
Conclusion
Hummingbirds hitting windows generally occurs due to territorial behavior, inability to perceive glass as a barrier, or attempting to access perceived food sources behind glass. While the collisions appear trivial, they can seriously injure or kill hummingbirds that cannot afford disrupted feeding.
With a little foresight, there are effective solutions for deterring hummingbirds from window collisions in your yard. Strategically placed deterrents, managing feeder proximity, closing curtains, and rerouting flight paths can significantly improve window strike outcomes. Implementing even small changes can help save hummingbirds and prevent losing their vital pollination contributions in your local ecosystem. With some mindfulness, you can resolve hummingbird window hazards and transform collision zones into a safer sanctuary.