Depth Perception on geese?

[GVGoose]

Do geese have depth perception? I've heard that they do and they don't. So if they don't wouldn't a super mag decoy and a standard decoy look the same?

[Michael Weiss]

Andrew, I saw this post and thought maybe I could help out a little, though I am not a Pro-Staffer, I think I can answer this question. Geese and ducks alike do not have the best depth perception, hence to use of massive sized decoys used to kill geese only 5-10 years ago. This is also true because of the morphology of the head. The eyes are spaced out and to the side of the head (like a turkey), thus sacrificing depth perception. SO, you are better off to use decoys in the same size range (life size to say a lesser.....than to use standard field shell compared to a decoy that dewarfs the others). This is why realism is the key. Gesse are getting smarter and harder to hunt, you have to stay on the game. Hope this help in some way.

-Weiss

[Bill Cooksey]

As with many animals, I am certain waterfowl see things differently than us. I take issue with the old depth perception theory though. If the setting of the eyes inhibits depth perception, I don't believe mallards, teal and wood ducks could perform the acrobatics most of us have witnessed in the timber. Certainly an occasional duck messes up, but most of the time they make it without a problem.

This theory stems from the fact that a goose or duck will only have a full visual if their heads are turned to the side so that one eye can focus completely, but I do know that a person who is born with one functioning eye is still capable of exceptional depth perception. My son was born this way, and this was one of my first concerns. Upon consulting many physicians, it became obvious that this was the least of our problems. As a matter of fact, Babe Ruth had only one functioning eye. To hit a ball like he did takes depth percetion in addition to hand-eye coordination.

I feel that the reason over-size decoys will fool birds at times has more to do with their lack of reasoning ability than lack of depth perception. If they are fooled too many times by decoys that do not look exactly like birds they will develop a conditioned response, and will not work decoys with that appearance. Their social nature is really their weakness (except in the case of snow geese), and if you are able to make your spread look like the real thing success will follow.

Bill

[Scott Turpen]

A scientific explaination:
EYE ANATOMY: all birds have a small separation between the anterior (cornea and lens) and posterior (eye ball) sections of the eye. within this separation there is a ring of 12-15 tiny bones. there are 2 striated (long) muscles that attach these bones to each other and they connect the posterior and anterior sections of the eye. these muscles and bones are used to focus on objects. in birds, the cornea and lens change their curvature in focusing by using these muscles and bones...only the lens does this in mammals. this anatomy gives birds a much more accute focusing capability (refractive power) than humans.
the retina and fovea control sharpness and color contrasts. within the retina, cone cells (color absorption) and rod cells (light absorption) exist. nocturnal animals such as deer, walleyes, and whiporwills have a greater number on rod cells for more light absorption for their nocturnal existence. most birds; however, have a greater number of cone cells because they rely on color so much. cone cells allow for sharpening of images no matter where light strikes the retina. sparrows have counts as high as 400,000 cone cells per square millimeter, ducks have approxiamtely 650,000 per sq./mm and eagles are in the neighborhood of 1,000,000 per sq./mm....consequently, humans have about 200,000 per sq./mm.
the fovea is known as a deep depression within the retina. like a ditch. this depression actually allows for interpretation of depth perception and movement. a birb's fovea (ditch) is deeper within the retina than a humans. this ditch acts as an elongated piece of glass for extra power. it acts as a pair of binoculars basically. some birds that are fast flying such as falcons and doves have two foveas for detecting movement and depths at high speeds. eye position and fovea placement are directly related. the faster flying the bird is, the more forward the eyes are placed on the head for a more binocular vision. the slower the flying the bird is, the further back the eyes are positioned on the head for better peripheral vision. think about an eagle compared to a goose.

[Jim Thompson, Jr.]

If fowl didnt have great depth perception how would they know when there the exact moment was to touch down,theyd just slam into the ground or water without it. Two different size decoys look like two different size decoys.Depth perception has every to do with other reference subjects.Without all the technical aspects to what degree would depth perception be off,would a mouse appear the same size as a barn or a pop can,cat,dog,pickup,combine,house.Is there a point at which half the size converts to the same size and a quarter then becomes half.

[Zach White]

I have a question about this whole depth perception....not about decoy size but about hiding blinds. If i were in corn and my blind from above appears too dark... geese will flair expecially if the geese come in high like snows and specks on no wind days. Does that have to do with the height of the blind or does it have to do with how i cover the blind with stubble? We try to elliminate shadows the best we can but sometimes it doesnt work...and help with this?

[ShortReed]

I know for a fact that they suffer from a lack of depth perception... shortly after a debilitaing blow from my Benelli!!! tongue.gif

Taking a note from Jim, I would agree that birds would be flat on their faces when they land if they had no depth perception... seems pretty much a logical conclusion without getting too techy. That was quite an enlightening post by TN.

My question is this Jim... from your post, if you can answer this question...
Is there a point at which half the size converts to the same size and a quarter then becomes half? I'm hoping you can tell me this... a glass of milk contains exactly half the volume it is capable of storing. Is the glass half full or half empty?!?!?! :D

[Michael Weiss]

TN Hunter is on the money! Now, it is not so much they have NO depth perception, it is just not that good. I agree, if they had really bad DP, they would crash landing all the time. Now, with that said, Bill raised a good point about ducks in the timber and manuvering through trees in low light situations. On more than one occasion, I have witnessed ducks and geese come into contact with one another and other objects on more than one occasion. Which got me thinking back to 2 summers ago. During a boat outing, myself and three others witnessed a gadwall hen fly into a tree limb and it broke her neck! I have never thought about that until this subject was brought up, but if waterfowl have "good" DP, she would have seen that limb and simply flew around it, right? Who knows...but one thing is for sure.....we will never truley know until we see things through there eyes. Good Question DuckAvenger!!

-Weiss

[Shoot-n-Release]

If anyone has watched 3 or 4 drake mallards go after a sussie in the spring , with their attention focused, it is quite a display of air acrobatics!!!!! You could'nt watch that and say they don't have good DP Bruce :rolleyes:

[Bill Cooksey]

Goose119,

I've seen several ducks collide with trees, but it the exception that proves the rule. There are many factors that could be at play. We know how things like wind shear can affect aircraft, so I can certainly imagine that a duck could misjudge air currents that are being batted about by the trees. The same could apply to birds flying in a flock. When only a few feet seperate them there has to be some effect from the other birds wind displacement. Remember "Top Gun"?

Of course those birds who take themselves out of the gene pool by colliding with solid objects could also be explained as Darwinism in it's truest form. ;)

Bill

[Rick Hall]

Not being "pro staff," I've stayed clear of this question but can't stand it any longer. The notion that ducks and geese have no depth perception is usually credited to the fact that their eyes are spaced to offer advantages other than the "binocular vision" credited for depth perception in humans and other creatures with their eyes in the front of their heads.

But ducks and geese (and other birds with their eyes on the sides of their heads) have evolved to depend, instead, on the speed at which things approach for depth perception. A web search will turn up more thorough explaination, but the bottom line is that their depth perception is simply different.

(And bigger decoys are simply that much easier for educated birds to see for the fakes they are.)

[Scott Turpen]

I have read quite a bit on the subject and the reason they can fly in formation is their DP at a distance is not that great but up close they have somekind of depth orientation.

Could be the reason the duck flew into the limb is it was just clumsy like me.

[Michael Weiss]

Bill,

That is an excellent point that I never thought of. This question has really got the wheels spinnin'. Hey, thanks again for the hat......

-Weiss

"WE Mavrick....."
"Sorry Goose, We were inverted." ;)

[GVGoose]

thanks for all the replies guys! So I guess my next question is do I keep my magnum shells then? Because right now i have 20 standard shells (22 inches) and 12 magnums (i think 30 inches not sure tho) so will this create an "unreal" look?

[Travis Mueller]

I think my depth perception is pretty good and I run into things on a daily basis. I honestly think that gadwall was daydreaming. Bruce is right. Those boy's are the blue angels when in comes to chasin the tale.

[Rick Hall]

DA - Given your location, I'd assume you're hunting Canadas and that you see considerable size difference in the real deal, so from the standpoint of simple size variation, using both standard and magnum decoys would seem, and may well be, a good thing. I'd think, for instance, that a mix of standard and "lesser" Canada full-bodies could add "life" via realism to a spread.

What a great deal of experimentation has shown me about magnums, however, is that their ready visability advantage can become a real disadvantage when well educated geese start looking hard at them.

This first came to my attention some years back when a carver friend hand painted a set of Big Foots to match his live specklebelly models, and they didn't prove the big magic we expected them to be. Then Big Foot made a run of specklebelly decoys, and thinking my friend's lack of fortune with his customs an anomoly, I bought some of my own and prepared to set the world on fire. Wrongo, froggy.

Much as I wanted my $36 per investment to pay off and hard as I tried to stick with it, they simply weren't as effecive as the standard size G&H shells I'd previously settled on. Birds were more apt to push off the, I thought, more realistic Big Foots than the smaller shells. Presumably because their additional size made them easier for decoy shy birds to spot as such.

As a related aside, the later in the season it gets, the more apt we are to cut back decoy numbers for that same reason and to "hide" even the most realistic of decoys a bit by placing them near rough or shaggy ground features.

(Bill, I got your PM and play pass. Thanks!)