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Beavers build dams of branches and mud that turn streams into ponds and wetlands, raising the water table and reshaping whole valleys.

U.S. Fish & Wildlife Service

ScienceNatureClimate

The story behind the card

Beavers build dams to create deep water around their lodges, where they can hide from predators and store branches for winter. The ponds slow floods, trap silt and keep the ground wet through dry spells, making room for fish, frogs, insects and birds. Because their work creates habitat for so many others, ecologists call beavers ecosystem engineers. A 2020 study of wildfires in the western United States found that stretches of stream dammed by beavers stayed green while the land around them burned. Some land managers now reintroduce beavers, or build simple beaver-style dams of posts and branches, to restore streams. Beavers can also flood farmland and roads, so they are not welcome everywhere.

Türkçe oku
Kunduzlar dal ve çamurdan barajlar kurar. Bu barajlar dereleri gölete, çevrelerini sulak alana çevirir; yeraltı suyunu yükseltir ve bütün bir vadinin görünümünü değiştirir.

Kunduzlar, yuvalarının çevresinde derin su olsun diye baraj kurar; böylece avcılardan saklanabilir, kış için dal depolayabilirler. Oluşan göletler taşkınları yavaşlatır, suyun taşıdığı mili tutar ve kurak dönemlerde toprağı nemli tutar; balıklara, kurbağalara, böceklere ve kuşlara yer açar. Yaptıkları iş pek çok canlıya yaşam alanı yarattığı için ekologlar kunduzlara “ekosistem mühendisi” der. ABD'nin batısındaki orman yangınları üzerine 2020'de yapılan bir araştırma, kunduzların baraj kurduğu dere boylarının, çevredeki arazi yanarken yeşil kaldığını gösterdi. Bazı arazi yöneticileri bugün dereleri eski hâline getirmek için kunduzları yeniden doğaya bırakıyor ya da kazık ve dallardan kunduz barajına benzeyen basit setler kuruyor. Kunduzlar tarlaları ve yolları da su altında bırakabildiği için her yerde hoş karşılanmaz.

Sources and further reading

Background reading: Beaver dam
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