• View from Sourdough Mountain Overlook  A view looking down onto Diablo Lake. Photo Credit: NPS/Michael Silverman, 2010.

    North Cascades

    National Park Washington

There are park alerts in effect.
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  • State Route 20 closed at Mile Post 134, Ross Dam

    After a brief closure at Newhalem due to an avalanche and unstable conditions, SR 20 has re-opened to its normal winter closure point at MP 134, Ross Dam. The highway will remain closed from Ross Dam to MP 171 (Silver Star Creek) until spring re-opening. More »

  • Ross Dam Haul Road Closure Continues

    A short segment of the Ross Dam Haul Road between the Diablo Lake suspension bridge and the tunnel remains closed to public use due to continued recovery following a March 2010 landslide. The closure will remain in effect through 2014. More »

  • Notice of planned work for the Cascade River Road, fall 2014

    Visitors planning to access the park via the Cascade River Road after Labor Day should be advised that the Park Service is planning a fall closure of this road at Eldorado Creek (3 miles before the end of the road) in order to perform permanent repairs. More »

Sound and Wildlife

Pika. Image Credit: NPS/Anderson
Pika use shrill cries to warn of danger but also sing with potential mates.
NPS/NOCA/Anderson
 

In the wild, the ability to hear is so important for survival that no deaf vertebrate species are known to exist. In addition to producing sounds for communication, animals continuously detect sounds, even when they are asleep. Losing the ability to hear those sounds because of inappropriate or excessive noise can have serious consequences. It may mean missing the footfall of a predator or failure to adequately compare songs from potential mates. Appropriate soundscapes are important for animal communication, territory establishment, courtship and mating, nurturing young, and effective use of habitat. Scientific studies have shown that wildlife can be adversely affected by high levels of noise. Although the severity of the impacts varies depending on the species being studied and other conditions, research has found that wildlife can suffer adverse physiological and behavioral changes from noise and other human disturbances.

For example:

  • Noise has been associated with suppression of the immune system and increased levels of stress-related hormones in animals.
  • Studies have shown that songbirds living in noisy places have to sing louder than birds in quieter environments. Birds forced to sing at a higher volume have to expend increased levels of precious energy to attract a mate or warn of predators.
  • Bighorn sheep are less efficient at foraging for food when they are exposed to aircraft noise, and mountain goats often flee from the sound of helicopters and airplanes.
  • Research has demonstrated that noise can adversely affect reproductive success in caribou and communication in whales.


When these effects are combined with the other sources of stress experienced by wildlife such as winter weather, disease, insect harassment, and food shortages, noise can have important implications for the health and vitality of wildlife populations within a park. By protecting the integrity of park soundscapes, creatures big and small have a better chance of reproduction and survival in the wild.

Did You Know?

Junior Ranger Totem: Raven

Anyone can become a North Cascades Junior Ranger! Pick up one of the four FREE activity booklets at any of the visitor or information centers. Complete the activities and earn your official junior ranger badge! Download the booklet here. More...