What a Leaf-On Aerial Can and Cannot Tell You About Cover

A growing-season aerial shows the top of the vegetation on the day it was flown. Deer bed in cover at ground level, and a summer photo cannot measure that layer. This guide gives you a five-class check for sorting each dark patch into what the photo can support and what only a later image or a walk can settle, so any bedding zone you draw rests on cover you have confirmed.

The National Agriculture Imagery Program (NAIP) is a good yardstick for any leaf-on layer because USGS documents it in detail. It is orthorectified aerial photography flown during agricultural growing seasons, in "leaf on" conditions, across the conterminous United States. Ground resolution was 1 meter from 2003 through 2017, and the standard became 0.6 meter in 2018. The flying cycle moved from five years (2003 to 2009) to no longer than three, and a tile may carry as much as 10 percent cloud. Contracts require well-defined points to fall within 6 meters of true ground at 95 percent confidence, about 20 feet, so treat the edge of a soft feature such as a thicket as looser than that.

Two things follow for cover. Every pixel is the top surface of whatever stood there on the flight date, and a given spot can go years between flights. FDR's leaf-off imagery guide shows how to audit the age of your app's imagery, so this guide skips that step and asks what the picture can say about cover once you know its date.

Purdue Extension's guide to assessing land for wildlife lists four basic requirements for every species: food, water, shelter and space. It adds that deer, songbirds and wild turkeys may use a property for only part of those needs. Read a photo the same way. A dark block of timber shows that woods exist, and it does not show how thick the understory is.

Purdue's management table treats the layer below the canopy as something land use changes. Keeping livestock out of a woodlot is listed as a way to get "thicker stem density for cover," and letting shrubs, vines and blackberries develop along woods edges is listed as a source of food and cover. From above, a grazed woodlot and an ungrazed one can wear the same canopy.

Wildlife Illinois describes Illinois deer as generalists that occur in or near wooded areas, particularly along streams or next to farmland, and says they forage away from woods but require wooded areas for survival. Timber is part of the answer, and a leaf-on photo finds timber well but cannot grade it.

FDR treats bedding as a cover-driven zone, never a point on a landform. Its Reading the Ground paper draws the line from the terrain side: the ground tells you where deer travel, and the cover tells you where they bed. For cover-first bedding on flat ground, see Finding Buck Bedding in Flat Farmland.

Force each patch into a single class. If it will not fit, it is not a hunting candidate yet. The table is a working tool from FDR's desk, not a published cover census.

Purdue's table lists small conifer plantings as cover during harsh weather, which is why class B earns the word candidate. The photo still cannot say whether your patch is one.

Suppose a dark block of timber sits between a bean field and a house. The photo supports class A with an E flag: woods, with people close. The plan is a downwind edge walk in late summer on ground you own or have permission to enter, and no October sit in the middle of the block. A winter image then gets a vote. FDR's leaf-off guide says winter photos separate timber types by color and texture, with bare gray oak ridges, dark cedar draws and feathery brushy cuts. A stand that reads as bare gray hardwood with no dark or brushy patches moves to the bottom of the walk list, and a patch that stays dark in January moves to class B and goes to the top.

Walk the edge, never the middle, and only on ground you own or have permission to enter. The photo cannot answer three questions, and the ground can:

If you can see 20 yards through the patch at chest height, drop the cover claim that day. One walk is a sample of one day, so the sign you find says deer used the ground at some point and does not say when or how often.

A winter aerial is a second date, not this week's ground. If two dates disagree, believe the later image for objects you can see, and believe neither for animals. The leaf-off guide covers what winter photos show about timber edges, thickets and trails, so this guide stops at classification.

Pick one dark patch on the county you hunt and put it in a class. Write down the single observation that would kill it, such as a clear sightline at 20 yards, and then go look. The photo poses the question and the ground answers it.

If you want a winter layer to pair with this check, see what Scout maps. FDR's Scout features page lists statewide 6-inch leaf-off imagery flown in 2025, illustrated with Pike County timber.