seasonal appearances of western tanager, Cassin's vireo, pine grosbeak, woodpeckers such as the pileated woodpecker and primarily ground-dwelling birds such as the sooty grouse. The peregrine falcon is the only species found in the park that is federally designated as an endangered species, while the marbled murrelet and northern spotted owl are listed as threatened. There are at least 28 species of fish documented, including all five species of Pacific salmon: pink, chinook (king), sockeye, coho and chum. Various trout species including rainbow, lake and brook trout can be found as can the largemouth bass and longnose dace. Seven species of reptiles and about a dozen species of amphibians have been documented. Reptiles such as the northern alligator lizard and the common garter snake and amphibians such as the western toad, Pacific giant salamander and rough-skinned newt reside in the park. More than 500 species of insects have been recorded, including at least two dozen species of butterflies. Around 250 species of aquatic invertebrates can be found in the parks waterways. Fire In North Cascades National Park, fire was used by Native Americans in the region near present-day Ross Lake to clear out brush, to ease foot travel, and possibly to flush animals out of the foliage. Evidence found in the patterns of tree growth as well as from tree ring analysis indicates human-caused fires were created for many hundreds of years. Similar evidence is found in the Stehekin Valley, where both smaller low intensity fires and larger fires are suggested by the growth patterns and burn scars in tree ring evidence. The low-intensity fires that were likely human induced were only found in the easternmost regions of the park. In the subalpine regions such as the Thunder Creek area, the studies concluded fire occurs at frequencies ranging from 30 years to 400 years. Across the entire North Cascades National Park Service Complex, between 1973 and 2003, there were 113 human-caused fires that burned , and 264 lightning-caused fires that burned . During this period, the largest fire consumed , mostly in Ross Lake National Recreation Area. North Cascades National Park Complex has three different zones with varying ratings for fire potential and severity. The park is managed as the Skagit Fire Management Unit (FMU) and has a low frequency of large natural fires that occur on average only every 50 to 400 years. North Cascades National Park has a