Ischaemum byrone



Common Names: Hilo Ischaemum, Hilo Murainagrass
U.S. Fish and Wildlife Service Listing Status: Endangered
Photos courtesy of NPS

Species Description
Ischaemum byrone is a perennial grass with creeping underground stems and erect stems between 16-31 inches tall.  Little is known about the grass’s life history.  Ischaemum byrone typically occurs in coastal shrublands and plants are generally restricted to the coastal strand on low cliffs usually growing in the cracks of pahoehoe lava sea level up to 250 feet in elevation.

Species Distribution
Ischaemum byrone was historically distributed over several of the Hawaiian islands including Oahu, northeast Molokai, east Maui, and the eastern coast and inland portion of the Big Island (Hawaii).  Currently, Ischaemum byrone populations have been identified on Kauai, Molokai, Maui, and Hawaii.  On the Big Island, populations are primarily known from the eastern and southern coasts.  National Park Service (NPS) properties with current populations of Ischaemum byrone are Hawaii Volcanoes National Park (HAVO) and Haleakala National Park (HALE).  There are no current populations of Ischaemum byrone on Kalaupapa National Historic Park (KALA) .

Biological Concerns and Threats to the Ischaemum include alien plant invasions, sea level rise, habitat degradation caused by cattle and feral animals, development, volcanic activity, and small population sizes.  Ischaemum is a perennial grass that typically occurs in coastal shrublands.  Plants are most commonly found among rocks and on cliffs from sea level up to 250 feet in elevation.  The most serious threat to the Ischaemum is the invasion of exotic grasses.  Exotic grasses are aggressive competitors that exclude native species by preventing germination and seedling establishment.  Dense stands of exotic grasses also increase the frequency and intensity of wildfires to the detriment of native species.  Grazing by deer (Axis axis) and feral goats (Capra hircus) is also a significant problem for Ischaemum.  Ungulates consume plants and degrade native ecosystems by creating eroded habitats conducive to the progressive intrusion of exotic vegetation.  Some Ischaemum populations are also threatened by the expansion of residential development or coverage by lava flows.  In addition, the small number of extant individuals also makes this species very vulnerable to extirpation from natural events including landslides, floods, volcanic activity, trampling by people, and fires. 

Critical Habitat: When a species is proposed for listing as endangered or threatened under the
Endangered Species Act (Act), The U.S. Fish and Wildlife Service (USFWS) must consider whether there are areas of habitat that are believed to be essential to the species’ conservation. Those areas may be proposed for designation as “critical habitat.” The determination and designation of critical habitat is one of the most controversial and confusing aspects of the Act.

What is critical habitat?
Critical habitat is a term defined and used in the Act. It is a specific geographic area(s) that contains features essential for the conservation of a threatened or endangered species and that may require special management and protection.  Critical habitat may include an area that is
not currently occupied by the species but that will be needed for its recovery. An area is designated as “critical habitat” after a proposed Federal regulation is published in the Federal Register and  public comments are received and considered on the proposal. The final boundaries of the critical habitat area are also published in the Federal Register.

Biologists consider physical and biological features needed for life processes and successful reproduction of the species. These include:
* space for individual and population growth and for normal behavior;
* cover or shelter;
* food, water, air, light, minerals, or other nutritional or physiological requirements;
* sites for breeding and rearing offspring; and
* habitats that are protected from disturbances or are representative of the historic   geographical and ecological distributions of a species.

What is the purpose of designating critical habitat?
Federal agencies are required to consult with USFWS on actions they carry out, fund, or authorize to ensure that their actions will not destroy or adversely modify critical habitat. In this way, a critical habitat designation protects areas that are necessary for the conservation of the species. A critical habitat designation has no effect on situations where a Federal agency is not involved—for example, a landowner undertaking a project on private land that
involves no Federal funding or permit.

Do listed species in critical habitat areas receive more protection?
An area designated as critical habitat is not a refuge or sanctuary for the species. Listed species and their habitat are protected by the Act whether or not they are in an area designated as critical habitat.  In consultation for those species with critical habitat, Federal agencies must also ensure that their activities do not adversely modify critical habitat to the
point that it will no longer aid in the species’ recovery. In many cases, this level of protection is similar to that already provided to species by the “jeopardy standard.”  However, areas
that are currently unoccupied by the species, but which are needed for the species’ recovery, are protected by the prohibition against adverse modification of critical habitat.

Source:  U.S. Fish and Wildlife Service. 2005. Critical Habitat – What Is it?  Endangered Species Program bullitan.  Found on the web at:
Accessed on November 15, 2007.