Defining Habitats in the NatureMapping Program
Wildlife use different habitats during the day or seasonally. Some species will be found in specific habitats (i.e., wetlands) or even microhabitats (i.e. puddle of water left over from a rain), while others may use multiple habitats. Habitat size is also important. Habitats can be as small as a 1-acre backyard or as large as a city. It often helps to look at the bigger picture to determine habitats. For example, if you see a bird in a tree, is the tree in a forest or in a park? A forest bird may not use a plot of 10 trees in a city, even if the trees are the same size and species the bird would use in the forest. The plot of 10 trees would become a component of the dominant habitat, which could be an upland deciduous forest or a city park.
NatureMapping looks at habitats the size of football fields (1 hectare, or 2.5 acres) or larger (up to 100 hectares, or 250 acres). Any habitat that is smaller than the size of a football field will be included in the dominant habitat surrounding it. NatureMapping also looks at linear habitats, such as rivers or roads, that have length but little width. Linear habitat lengths include 1, 2 and 5 miles.
A helpful way to decide the habitat type is to look down from above, as if you were a soaring Broad-winged Hawk. Plants and animals (this includes humans) respond to the structure, maturity, and size of the habitat. Taking a bird’s-eye view gives a different perspective than being on the ground and looking around. Picturing the landscape from above allows you to easily distinguish between major differences in vegetation, one of the main considerations necessary to choose habitats for NatureMapping. Being on the ground will help you see the structure, perhaps even better than from above for many habitats.
For example, a plot of newly planted trees is not a forest. Chances are, they are planted in rows. Forests are "planted" naturally and have been allowed to mature to a point where there is a diversity of plant species and structure, at all heights, from ground to canopy. Forests have an understory or ground layer, made up of herbaceous plants. They also have a midstory, containing trees and shrubs that grow to a medium height. Finally, forests have an upperstory, made of trees that grow over the top of everything below, creating abundant shade with their interlocking crowns. Each layer supplies wildlife with the necessary food, water, shelter, space, and structure necessary for survival. The Broad-winged Hawk will not nest in a plot of newly planted trees, or perhaps even a plot of mature planted trees. Instead, this hawk requires a mature forest that has all of the components described above. A plot of planted trees would more accurately be described as a "plantation."
Grasslands, like native remnant tallgrass prairies or mature reconstructed prairies, behave similarly to mature forests. Again, these prairies have the right combination of plant species and structure necessary for a particular group of nesting birds, reptiles, amphibians and mammals to survive. A pasture or even CRP planting may have a smaller list of species, even a relatively diverse list, but chances are, it won't have the same structure as a remnant tallgrass prairie or reconstructed prairie planted deliberately for the purpose of being a prairie. For other examples of NatureMapping habitats, go to Habitat Descriptions/Codes. To practice choosing habitats, visit the Selecting Your Monitoring Site Habitats page.
Note: If a given monitoring site has habitats that are smaller than a football field, then the habitats are grouped into the primary, or dominant, habitat of 1 football field sized area or larger. For example, a backyard smaller than 1 hectare wouldn't be considered a habitat. However, if the yard is a part of an entire neighborhood of houses, then the habitat would be "Residential."