When we think of attracting wildlife we often think of bird feeders, bird baths,
and bird houses. Creating artificial places to substitute for nature can allow
wildlife to live in places where natural habitat no longer exists and can also
provide convenient viewing for animals that might otherwise be difficult to
observe. But when it comes to attracting wildlife, doing less is often best.
Nature is very efficient at producing the things necessary to attract wild
animals - food and shelter. Leaving an area of the yard to grow unhindered
can naturally provide nesting places, hiding places, and food for birds, small
mammals, reptiles, amphibians, insects, etc. Of course, we might want to
help things along a little. We can often improve the habitat with a little work.
Removing some of the more invasive weeds, such as Honeysuckle vines or
Garlic Mustard, can improve the diversity of life the wild area can support.  
Some things that make a yard more attractive to wildlife include:

Dead trees - leaving dead trees standing when it is not in a
               position to fall on a house or road or otherwise
               cause a hazard creates shelter, nesting places,
               and food for a variety of wildlife, as well as perches
               for birds. Larger dead trees might be cut down to a
               level where they are not a hazard, leaving as much
              as possible standing.

Dead Logs - Logs, particularly hollow logs, provide habitat for
              salamanders, insects, reptiles, and small mammals.

Water - All life needs water. A source of fresh water can be a
               bird feeder, a small dish regularly filled, or a small
               pond. A small pond will be most effective.

Rock Piles and Natural Stone Walls - Provide cover for a variety
               of wildlife.

Bird Houses, Bat Houses, and Squirrel Houses - placing artificial
              homes can replace lost habitat when it is not
              possible to provide the real thing.

Plants - Plants should be chosen to provide food and shelter.
              Planting dense brush provides nesting and shelter.
              Native plants can be selected that provide food
              and shelter.

Pesticides and Herbicides should be avoided. Chemical pesticides cause
diseases including neurological disorders, cancer, hormonal imbalance, and
respiratory problems in wildlife, pets, and humans. They disrupt the balance
of nature by killing natural predators, often killing predators more effectively
than they kill pest species. Consider installing a bat box and bird nesting
boxes to help control pests. Encourage native predators to keep the pests
in check when possible.

People farmed effectively and grew productive gardens for thousands of
years before chemical pesticides began to be applied in the 1940s. There
are age old techniques that are effective and healthy for the environment,
for you, for your children,
for your neighbors, and for your pets.

Some reasons to avoid chemical lawn and garden treatments
are listed
below. Dogs tend to be closer to the ground than humans, sniffing and
eating grass and other things off the ground, so their exposure is likely to
be greater than humans. Wildlife is likely to also have a high level of
exposure, as are small children who play on treated lawns:

Canine malignant lymphoma has been associated with dog owner use of
commercial lawn pesticide treatments.
(Cancer Res. 1992 Oct 1;52(19 Suppl):5485s-5488s.
Pesticides and non-Hodgkin's lymphoma.
Zahm SH1, Blair A.)

Exposure to herbicide-treated lawns has been associated with significantly
higher bladder cancer risk in dogs. (Sci Total Environ. 2013 Jul 1;456-457:
Detection of herbicides in the urine of pet dogs following home lawn
chemical application.Knapp DW1, Peer WA, Conteh A, Diggs AR, Cooper
BR, Glickman NW, Bonney PL, Stewart JC, Glickman LT, Murphy AS.

Exposure to lawns or gardens treated with herbicides was associated with
an increased risk of Transitional Cell Carcinoma in dogs. (J Am Vet Med
Assoc. 2004 Apr 15;224(8):1290-7.Herbicide exposure and the risk of
transitional cell carcinoma of the urinary bladder in Scottish Terriers.
Glickman LT1, Raghavan M, Knapp DW, Bonney PL, Dawson MH.)