Research Outline

Wildlife Sheltering Capacity of a Single Tree


To find out details about what types of wildlife and how many species of wildlife a single average tree generally shelters.

Early Findings

Types of Wildlife Sheltered by Trees

  • Trees support various types of wildlife, such as birds (like woodpeckers, owls, songbirds, and ducks, among others), insects, squirrels, caterpillars, butterflies, moths, salamanders, black bears, bats, and raccoons.
  • Arboreal animals like sloths, koalas, geckos, opossums, tarsiers, flying snakes, spider monkeys, tree pangolins, harvest mice, tree kangaroos, and gibbons all dwell on trees.

Number of Species of Each Type Sheltered by a Single Tree

  • Oak trees "provide a rich habitat and support more life forms than any other native trees."
  • A single oak tree hosts 532 species of caterpillars.
  • A single oak tree also shelters 147 species of birds, 120 species of mammals, and 60 species of reptiles and amphibians.
  • A mature oak tree supports more than 280 species of insects.
  • Different types of trees support different numbers of wildlife species. The following trees support these numbers of insect species: common alder (90 insect species), ash (41 insect species), quaking aspen (90 insect species), beech (64 insect species), crabapple (90 insect species), hawthorn (149 insect species), small-leaved lime (31 insect species), rowan (28 insect species), silver birch (229 insect species), and white willow (200 insect species).

Favorite Trees for Wildlife

  • According to the National Wildlife Foundation, the ten native trees that support the most wildlife are red cedar (30 native butterflies and moths), oak, willow, red mangrove (628 species of birds, mammals, reptiles, amphibians, and fishes), ponderosa pine, beech, cherry, plum, longleaf pine (30 threatened and endangered species, including red-cockaded woodpeckers and gopher tortoises), and cottonwood.
  • Dead trees provide shelter to over 1,000 species of wildlife, including salamanders, ants, beetles, snails, chipmunks and squirrels.

Total Number of Living Species That Depend on a Single Average Tree

  • In 2017, 22 researchers from 13 different institutions participated in a study to determine the total number of living species, including bacteria, algae, fungi, lichens, invertebrates, wildlife, and plant life, that depend on a single average tree. The research team was supported by a National Science Foundation grant. The study was published as a paper called "Synthesis of phylogeny and taxonomy into a comprehensive tree of life." It was discovered that a total of 2.3 million living species depend on a single average tree. However, the study did not provide a breakdown by species.

Summary of the Early Findings

  • During the one hour allotted for our initial research, we searched the databases of wildlife foundations and eco-conservation associations for readily available information about the number of species that an average tree shelters. However, even an exhaustive research did not reveal any such database.
  • The absence of any database may be construed to the fact that different species of trees support different number of wildlife species. Also, the behavior of wildlife is highly unpredictable and depends on factors that include the presence of human habitation nearby, availability of water, and weather conditions.
  • Since data about an average tree is not available in the public domain, we considered an average oak tree as a proxy. This is due to the fact that oak trees support more wildlife than any other species of trees. Even for this particular type of tree, public information only reveals the number of wildlife species for any particular class, such as mammals, birds, or insects. Further details about the different types of birds (such as owls, woodpeckers, or songbirds) or mammals (bats, monkeys, or squirrels) or other wildlife are not available.
  • In addition to this public search, we scanned our proprietary research database of over 1 million sources and were unable to find any specific research reports that address your goals.