Feeder Types
Window Feeders
A feeder on the glass looks like the worst possible idea for window strikes. It is close to the safest place in the yard, and the reason is pure physics.
The short answer
- A window feeder mounts directly to the glass, usually on suction cups, and holds a few ounces of seed on a shallow tray.
- Mounted within about 3 feet (1 m) of the glass it reduces collision risk, because a startled bird cannot build up enough speed over that distance to injure itself.
- Suction cups fail from dirty glass, cold snaps and age, not from weight. Clean both surfaces, wet the cup, and replace the cups every year or two.
- Expect chickadees, titmice, finches, nuthatches and sparrows. Do not expect cardinals, jays or woodpeckers on a small tray.
- It is the single best feeder for an apartment window, a tiny yard, or anyone who wants birds at arm's length.
A window feeder is a small tray, usually 6 to 10 inches (15 to 25 cm) wide, that attaches directly to a pane of glass with suction cups. It holds a few ounces of seed and puts feeding birds about 18 inches (45 cm) from your face, which is a completely different experience from watching a pole feeder across the lawn.
It is also, counterintuitively, a window strike reduction measure. Collisions happen when a bird flying at speed reads a reflection as open sky or as a route through the house. A feeder on the glass eliminates the runway.
This page covers why the close distance is safe, how to make suction cups survive a winter, which species use a tray this small, and how to run one from an apartment window where no other feeder will fit.
Why the glass is the safe place#
The rule is about acceleration, not proximity. A small songbird flushing from a standing start covers the first foot or two before it has any real speed. If the glass is right there, the worst case is a bump and a startled bird that flies off.
Put that same feeder 15 feet (4.5 m) from the window and a hawk passing over sends the whole flock into the glass at full flight speed. That middle range is where fatal strikes cluster, which is the whole argument behind the one foot / thirty foot rule.
| Feeder distance from glass | Collision risk | Why |
|---|---|---|
| On the glass to 3 ft (1 m) | Low | No room to build speed |
| 3 to 15 ft (1 to 4.5 m) | Highest | Full speed, strong reflection |
| 15 to 30 ft (4.5 to 9 m) | High | Still fast, reflection still convincing |
| Beyond 30 ft (9 m) | Lower | Birds are less likely to line up on the reflection |
A window feeder is not a complete fix
It protects the birds using it. Every other bird in the yard still sees a reflection of trees and sky in that pane. If you have had strikes, treat the glass itself with closely spaced external markers, cord screens or patterned film, as covered in preventing window strikes. The feeder and the glass treatment do different jobs.
Making suction cups hold#
Suction cups do not fail because the feeder is heavy. They fail because of contamination, temperature and age, in that order.
Preparation. Clean the glass with rubbing alcohol or glass cleaner and wipe the cup face too. Any dust, pollen film or old adhesive residue lets air creep in. Wet the rim of the cup with warm water, press hard, and roll your thumb around the edge to expel the last of the air.
Temperature. Mount on a mild day. Rubber stiffens below about 40°F (4°C) and will not seat properly, and a cup mounted in summer heat often loosens on the first hard freeze. Recheck every cup at the start of winter.
Age. Cups last one to two seasons outdoors. Ultraviolet light hardens the rubber, and a hard cup will not conform to the glass. Replacement cups cost very little and are the fix for a feeder that keeps sliding.
Give it a safety line
Run a loop of fishing line or light cord from the feeder to a hook, a window latch or a nail in the frame. When a cup lets go in a February wind, the feeder swings instead of shattering on the patio. This is the single most useful modification you can make to a window feeder.
Not every model uses cups. Hook-on window feeders hang from the top of the sash and rest against the glass. In-window models slot into the track of a partly opened window and use one-way film so the birds see a mirror and you see the bird. Both hold better than suction cups; both are limited to windows that open the right way.
Which birds will use it#
A window tray is small, exposed and attached to a building, so it selects for bold, agile birds that feed in short visits.
| Likely | Sometimes | Rarely |
|---|---|---|
| Chickadees, titmice | Northern cardinal on a wide tray | Blue jays |
| House finches, goldfinches | Downy woodpecker if suet is offered | Mourning doves |
| White-breasted nuthatch | White-throated sparrows | Grackles and starlings |
Chickadees are nearly always the first to commit. They take one seed and leave, which suits a feeder with nowhere to sit and eat. Finches will settle in and stay for several minutes once they trust it.
Seed for a small tray#
Capacity is the constraint. Most window feeders hold half a cup to two cups of seed, which is one or two days of traffic in an active yard. Fill it accordingly and let it empty rather than keeping a stale reserve.
- Sunflower hearts are the best choice: no hulls to blow onto the sill, high fat, and every target species eats them.
- No-mess blends are the next best for the same reason, especially over a patio or a neighbor's balcony.
- Black oil sunflower in the shell works but leaves a drift of hulls directly below the window.
- Cheap mixes are a poor fit. Birds rake filler out onto the ledge, where it sits and rots.
Apartments, balconies and very small yards#
For a lot of people this is the only feeder that is physically possible. It needs no pole, no tree, no ground and no yard, and it can be refilled by opening the window.
Three practical points. Check what your lease or building association says about attachments and about feeding wildlife. Choose a window you can reach from inside, because a feeder that requires going outside with a ladder gets refilled far less often. And keep spill to a minimum with hull-free seed, since a shower of hulls onto the balcony below is how feeding privileges get withdrawn. More on both problems in feeding birds on a balcony or apartment and feeding birds in a small yard.
One more advantage of the format in a rented apartment: it leaves no trace. Suction cups come off with a fingernail and take nothing with them, which is not true of a bracket screwed into a window frame or a railing clamp that scratches paint.
Cleaning and drainage#
The tray is shallow and sits against a warm surface, so wet seed goes bad quickly. Check for drainage holes before you buy: a solid tray with a lip is a puddle waiting to happen.
Wash it every one to two weeks, more often in humid weather, and rinse the sill at the same time. It is the easiest feeder in the yard to clean because you can reach it from a chair, so there is no excuse for the moldy corners that plague pole feeders. The general routine is in how to clean a bird feeder.
Wipe the cups while you are there. Sap, dust and bird droppings on the cup face are what loosen them.
Expect a slow start
Birds approach glass with more caution than they approach a pole. Two to three weeks is normal before regular use, and putting a handful of seed on the sill nearby helps them find it. If nothing has happened after a month, the problem is usually the yard rather than the feeder, which is the diagnosis in how long until birds find a new feeder.
Before you stick it on the glass#
- Pick a window you look through daily and can open from inside.
- Choose the shadiest pane you have. Sun cooks seed and degrades suction cups fastest.
- Clean both surfaces with alcohol, mount on a mild day, tug-test before loading.
- Add a safety line to a hook or latch.
- Start with sunflower hearts, half filled.
- Treat the rest of the glass separately for strikes if you have had them.
- Consider a platform feeder elsewhere in the yard for the cardinals, doves and jays a window tray will never hold. If you would rather build one, there are plans in the DIY window feeder.
Frequently asked questions#
Are window bird feeders safe for birds?
Yes, when they are mounted on or within about 3 feet (1 m) of the glass. A bird flushing off a feeder that close cannot accelerate to a dangerous speed before it reaches the window, so impacts are bumps rather than injuries. The dangerous distance is the middle range, roughly 3 to 30 feet (1 to 9 m), where a bird has room to reach full speed and still mistakes the reflection for open sky.
How do I stop a window feeder from falling off?
Clean the glass and the cups with rubbing alcohol, wet the cup rim with warm water, press firmly to expel the air, and give the feeder a tug before you load it. Do it on a mild day, because cold glass and cold rubber both hold poorly. Recheck the cups monthly and replace them when the rubber turns hard or cloudy.
What birds use window feeders?
Chickadees and titmice are almost always first, followed by house finches, goldfinches, nuthatches, and sparrows. Bolder species like cardinals may visit a large window tray but often will not perch on a small one. Birds that need a stable landing surface, including doves and jays, mostly stay away.
Will a window feeder work on the outside of an apartment window?
Yes, and it is often the only feeder that fits. It needs no pole, no tree and no deck. Check your lease or building rules first, mount it on a window you can open or reach from inside for refilling, and keep the tray small so spilled seed does not rain onto a neighbor's balcony.
Do window feeders attract squirrels?
Only if there is a route to them. On a second-story window with no adjacent ledge, railing or downspout, squirrels are rarely a problem. On a ground-floor window they will find it within a week, and there is no baffle geometry that helps on flat glass.
How long until birds use a new window feeder?
Usually one to three weeks, longer than a yard feeder because birds approach glass cautiously. Scattering a little seed on the sill and keeping the tray stocked but not overfull speeds it up. Once one chickadee uses it, the rest follow quickly.