Nose - sense of smell
A deer's best defence, its most effective tool in judging its surroundings. A deer trusts its nose more than any of its other senses. This is a deer's most important sense when conditions are favourable.
Vision - the eye
The situation where deer most effectively use their vision is detecting movement. They pick up movement very well using their other senses in concert to determine the threat level, once movement is detected.
Deer see in the ultraviolet or extremely low light range. Deer have very good vision in the cold or blue range of the spectrum. They also can see the mid-range spectrum of yellow.
Hearing - the ear
The deer's hearing is its most important sense, because even if the wind is not favourable, there is the chance that the deer will hear something.
How well can a deer hear? Far better then us humans. With such large ears and being able to independently angle and rotate them, this enables them to hear more effectively then us. Deer can focus right into where they thought they heard the sound and pin point the source.
Deer often wait for corroboration from another of their senses for a danger warning. If the hunter can feed a buck's ears or nose false information, he may be able to get away with actually allowing the animal to see him.
How deer determine threatening sounds ?
This depends on many factors. Man made sounds like talking, yelling, coughing, slamming car doors are obvious alert sounds to deer. Now deer deep in the forest will not react to the same sounds as an urban buck for example. It is safe to say that sounds unfamiliar or out of the ordinary of a whitetails environment will warrant attention.
Big Bucks Notes
Pheromones deposited at signposts ( rubs and scrapes) by mature bucks may have a " bio-stimulating " or trigger effect on the breeding season.
Older bucks may also produce " controlling " or " priming " pheromones that yearling bucks are not physically mature enough to produce. *
(* Taken from QDMA's ? Whitetail Deer Report )
Bedding Sites - Thermal Currents
Whitetail bucks often bed with their backs to the wind, on a bench or rise, where they can smell and hear danger from behind them and see and hear danger below and in front of them. In hilly or mountainous terrain, thermal currents generally begin to fall late in the afternoon and rise in the late morning. When deer bed high during the day, rising thermal currents bring scents to them. When the deer move down to feed in the evening, the currents may be still rising, bringing scent to the deer as they walk downhill. When deer bed in low-lying areas at night, the thermal currents carry scent down to them. When they make their way to higher daytime bedding areas in the early morning, the currents may still be falling, bringing scent to the deer as they walk uphill.
The location where a buck decides to make a scrape is always dictated by the presence of an appealing over-hanging branch, about five feet above the ground. They are known as licking branches and bucks will chew the tip of the branch with his front teeth. He then rubs his face on the wet nub, depositing pheromone secretions from his forehead and preorbital glands, found near the eye pit toward the nose. A buck will always create the licking branch first, then paw the ground below and rub-urinate on the fresh earth. Combined, the licking branch and scrape are the whitetail's primary scent communication post during mating season. Scrapes and licking branches are also made and used by both bucks and does, year round.
Photo used under license ruewildlifephotos.com
Making a mock licking branch
Make a mock licking branch every 50 yards along a deer travel funnel. You can set up 2-5 licking branches, spaced 50 yards apart. The branch should be 5 1/2ft off the ground. Hang the branch on a wire over the trail between two trees. Be sure to expose the soil below the licking branch. Clear a shooting lane 10-15ft wide.
Photo used under license ruewildlifephotos.com
Rubs serve to mark the buck's territory and threaten other males, while also revealing his presence to females. Bucks carve off bark and rub in their scent to give notice that this is their turf. Several rubs made in one location indicates a bucks core area and would be an ideal spot to setup a treestand.
Areas with mature bucks can have 10 times as many rubs as areas without them. Mature bucks make about 35 percent more scrapes and 50 percent more rubs than yearling bucks.
A whitetail buck will dig a hole in the snow to bed down in. This one had melted snow at the base of the bed, indicating it had been recently vacated. The same buck may use this bed again for example, after feeding near by. Does will not use the same bed over again.
What we know about where mature bucks live. A bucks summer home range on average consists of 650 acres( 640 acres = 1 sq. mile ).
A bucks core area within this is 160 acres.
The fall home range is expanded to two sq. miles.