Conservation of Rare Species 

Thirteen species found in Ann Arbor parks are protected as threatened or endangered (7 plants, 5 birds, and 1 butterfly). An additional 14 wildlife species and several plant species are of special concern.   Source: Ann Arbor Natural Area Preservation

Animal species whose ranges are limited by their narrow habitat requirements, or other factors such as predation, habitat loss, or human activity, are listed as endangered, threatened, or special concern by the State of Michigan. Those animals listed as endangered or threatened are granted legal protection from harm.

How do threatened and endangered species affect our local environment?

Rare species contribute to biodiversity in City natural areas. In addition, many people feel a special affinity for rare species. Those who see a threatened Osprey or Loon along the Huron River during migration in the spring feel connected to other places far away. Those seeing our resident threatened and special-concern species, such as Grasshopper Sparrow or Blanding’s Turtle, are also reminded of the careful balance between all species. The presence of these species thus affects our human environment as well as the ecological balance.

How does NAP manage habitat to benefit rare species?

Managing habitat to maintain and enhance populations of rare species in City natural areas requires a clear understanding of the life history, behavior, and special food and habitat requirements of each species. Some examples of management techniques used by NAP staff are described below.

 

Hooded Warbler Hooded Warblers are “area-sensitive,” meaning that they are generally found only in larger tracts of mature forest. They nest in small clearings within these mature forests where a thick shrub understory is available. Females often place a nest in the low part of a small shrub at the forest edge. They are often associated with moist woodlands and ravines.   Sites: Bird Hills and Marshall Parks Management: Maintain native shrubs in understory for nesting cover and keep open areas open using burns and brush clearing.

 

Blue-winged Warbler Blue-winged Warblers usually nest in early- to mid-succession habitat with vegetation that is often a mosaic of dense growth of herbs, shrubs and trees. This mix of vegetation occurs at the edges of wetlands and damp areas or dry, upland habitat.   Site: Marshall Nature Area Management: Maintain thick native shrub and herbaceous mosaic at forest edges using patchy burns and removal of invasive species.

 

Bobolink Bobolinks originally nested in tall-grass or mixed-grass prairies in the Midwest. Due to the increase in agricultural prevalence, they have adapted to nesting in large hay fields and meadows (> 20 acres). Now, modern farming technology, which allows for fields to be mowed multiple times over the growing season, can cause near 100% mortality of nestlings when fields with occupied nests are mowed. Sites: Ann Arbor Airport, Wheeler Service Center hay fields and capped areas of former landfill. Management: Delay mowing of grasslands until after July 10, giving nestlings an opportunity to fledge prior to mowing. This has been so successful on City of Ann Arbor property that Bobolinks have begun nesting on the unmowed capped landfill sites where none had previously nested.

 

Duke’s Skipper The Duke’s Skipper is a small brown butterfly that inhabits wetlands, and is listed as threatened in the State of Michigan. The most significant threats to the Duke's Skipper are habitat fragmentation and alteration, pesticides, and invasive species. Sites: various sites in and around Ann Arbor Management: Remove invasive wetland plants such as purple loosestrife and glossy buckthorn, avoid prescribed burning in the areas in which Duke's Skipper is known to be found, and enhance butterfly habitat with additional nectar-producing flowers.

Herpetofauna Prescribed burning has the potential for both positive and negative effects on salamanders, frogs and toads (or “herps”). Herps populations may be effected by the reduction in leaf litter and large woody debris because these elements help them to retain body moisture and provide habitat for their prey. However, the chemical content of invasive plants such as garlic mustard can have a negative effect on herps, and invasive shrubs can cause changes in their habitat structure. Known herp locations are taken into consideration when planning the location and timing of burns. Post-burn survey efforts are completed to confirm herp locations after management.

General techniques used to reduce the impact of prescribed fire on the amphibian population include: buffer zones around wetlands, slow back burning to allow escape routes, mid-level relative humidity burn conditions to allow preservation of some leaf litter, no re-lighting to preserve refugia, a burn date shortly before herp emergence, avoidance of large woody debris ignition

More information

Natural Area Preservation

Michigan Department of Natural Resources

Last Updated September 2009