根返りした木は、土ごと倒れて根元は大きな土の塊となっている。この土の塊の中が生きものの越冬場所として好まれるようだ。オサムシ、ゴミムシ類の他に、カメムシ、ムカデ、トカゲ、カエルなども越冬している。皆、わざわざこの土の固まりに登ってから潜っているわけだ。（「 根返りで越冬するオサムシ」より引用）やがてミソサザイは、ピョンピョン飛んで奥に消えました。
ミソサザイの冬季のねぐら入りについて、特に雪国での具体的な情報は提供された検索結果には含まれていません。しかし、ミソサザイの一般的な生息環境と冬の行動から、以下のことが推測できます：ミソサザイは通常、山地の渓流沿いの藪や岩のある林に生息しています[3][4]。冬になると、より低い山地や山麓の沢や岩のある林に移動する傾向があります[4]。この習性から、冬のねぐらとして以下の場所を利用する可能性が高いと考えられます：1. 岩の隙間や穴2. 倒木の下や樹洞3. 厚い藪の中4. 渓流沿いの岸辺の植生の中雪国では、これらの場所が雪から保護され、比較的暖かい環境を提供すると考えられます。ミソサザイは体が小さいため、寒さから身を守るためにこのような隠れ場所を利用すると推測されます。ただし、ミソサザイの具体的な冬のねぐら入り行動については、さらなる研究や観察が必要です。Citations:[1] https://www.pref.niigata.lg.jp/site/aicho/20210401aicho.html[2] https://www.pref.niigata.lg.jp/site/aicho/20200401aicho.html[3] https://zukan.com/jbirds/internal14978[4] https://www.suntory.co.jp/eco/birds/encyclopedia/detail/1497.html[5] http://www.omnh.jp/wada/birds-rep11.html[6] https://www.omachi-sanpaku.com/common/file/sanpaku/backnumber/13-4_cmp.pdf[7] http://sizenkansatu.jp/05daigaku/s_2.html
The **Eurasian wren** (Troglodytes troglodytes) typically roosts in **dark retreats, snug holes, and even old nests** during the winter months. These roosting sites provide essential shelter from cold weather and predators. In harsher conditions, they may gather in groups, often consisting of family members or multiple individuals, to conserve warmth[1][3][6].They are known to utilize various habitats for roosting, including dense vegetation such as bushes, hedgerows, and brush piles. This adaptability allows them to find suitable roosting spots across a wide range of environments, from gardens and parks to more natural settings like forests and marshes[1][3].Citations:[1] https://www.allaboutbirds.org/guide/Eurasian_Wren/lifehistory[2] https://en.wikipedia.org/wiki/Winter_wren[3] https://en.wikipedia.org/wiki/Eurasian_wren[4] https://www.audubon.org/field-guide/bird/pacific-wren[5] https://animaldiversity.org/accounts/Troglodytes_troglodytes/[6] https://animalia.bio/eurasian-wren?letter=w[7] http://www.birdwatchingacademy.com/winter-wren/[8] https://www.allaboutbirds.org/guide/Winter_Wren/overview[9] https://www.discoverwildlife.com/animal-facts/birds/wren-factsEurasian wrens (Troglodytes troglodytes) do use man-made structures for roosting in winter, including nest boxes. While they typically prefer natural roosting sites, they have been observed using artificial structures when available:1. Wrens have been recorded roosting in large numbers in nest boxes during winter. In one instance, as many as 60 wrens were found roosting together in a single nest box[4].2. They are known to use various man-made structures for shelter, including stone walls and even old nests[3][5].3. Wrens often seek out "dark retreats" and "snug holes" for roosting, especially during harsh winter weather[3]. Nest boxes can provide such protected environments.It's important to note that wrens are adaptable and will use a variety of roosting sites. They may roost alone or in groups, with communal roosting being a common strategy to conserve heat during cold winter nights[4]. While nest boxes are not their primary choice, they can serve as valuable artificial roosting sites when natural options are limited or during particularly harsh weather conditions.Citations:[1] http://www.birdwatchingacademy.com/winter-wren/[2] https://animaldiversity.org/accounts/Troglodytes_troglodytes/[3] https://en.wikipedia.org/wiki/Eurasian_wren[4] https://scotlandsnature.wordpress.com/2019/01/16/a-small-bird-with-a-big-impact/[5] https://www.allaboutbirds.org/guide/Eurasian_Wren/lifehistory[6] https://www.backyardecology.net/winter-wren-one-of-our-other-wrens/
