Over half of all native birds are endemic. No native terrestrial amphibians or reptiles occur. There are several hundred species of endemic tree snails. Cave and anchialine pool fauna are present. Rainfall is highly seasonal in dry areas, and is less seasonal in wet areas.
Some snow occurs on highest peaks.
The growing season is mostly 365 days, decreasing to about 300 days at highest elevations. Surface Water Characteristics. Fast moving perennial streams are common in wetter parts of mountain areas. Few to no perennial streams occur elsewhere because of seasonal rainfall and a permeable substrate. Lava flows and ash and cinder falls periodically occur on the Island of Hawaii.