{"id":2376,"date":"2016-03-01T08:00:33","date_gmt":"2016-03-01T08:00:33","guid":{"rendered":"http:\/\/blog.cwf-fcf.org\/?p=2376"},"modified":"2016-10-12T20:56:57","modified_gmt":"2016-10-12T20:56:57","slug":"managing-the-deep-freeze","status":"publish","type":"post","link":"https:\/\/blog.cwf-fcf.org\/index.php\/en\/managing-the-deep-freeze\/","title":{"rendered":"Managing the Deep Freeze"},"content":{"rendered":"

\"cw_jf2016_birding\"<\/strong><\/p>\n

Some of Canada\u2019s hardier bird species brave the winter right here at home. They have some good tricks up their sleeves.<\/strong><\/p>\n

If you stood outside in just about any Canadian city during January or February without a stitch of clothing, you’d become a Popsicle in short order. So we don heavy coats, thermal mitts and wool-lined boots. But what about birds? Not all of them head to warmer climes in winter, so how do they cope?<\/p>\n

Actually, birds have an amazing number of behavioural and physiological adaptations for surviving the coldest of conditions. It has a lot to do with one of their unique features \u2014 feathers. If you’re looking for natural lightweight insulation, you can\u2019t find much better.<\/p>\n

A) DRESS IN LAYERS<\/strong><\/p>\n

Just like we throw on extra clothing to combat winter cold, some birds enhance their insulation from feathers by moulting into fresh, thick plumage. Some sparrows that spend their winters in chilly areas actually increase their plumage weight by as much as 70 per cent from summer to winter.<\/p>\n

Ever watch a bird on a really cold day fluff out all its feathers so that it looks like a little butterball? The bird is simply adjusting its feathers to create warm air pockets to increase the insulation value of its plumage. It\u2019s the same principle as when you buy a winter coat \u2014 you want it a bit loose so that your body heats the trapped air to provide an extra layer of insulation.<\/p>\n

B) FANCY FOOTWORK<\/strong><\/p>\n

So, how about ducks and geese that spend hours bobbing around in water barely above freezing temperature? They have waterproof plumage, but what keeps their legs and feet from becoming frostbitten and eventually gangrenous?<\/p>\n

First, they reduce the circulation in their feet to a mere trickle in a network of blood capillaries. Just enough flows to keep the tissue cells alive. Second, through a special heat-exchange system, the arterial blood flowing to their feet heats up the cool venous blood returning to their body. All of this serves to keeps a water bird\u2019s heat from being lost to the outside. Birds have another trick we humans can\u2019t do. At night, especially in extremely cold weather, they can lower their body temperature a few degrees to conserve energy. When a bird becomes cold, it tenses its breast muscles and begins to shiver to generate body heat. Unlike us, they do this in an almost imperceptible manner.<\/p>\n

C) CHANGING HABITS<\/strong><\/p>\n

Birds also adjust their behaviour to cope with cold. In really cold weather, land birds favour sheltered or wind-protected areas for feeding and roosting. Waterfowl often tuck their heads into their \u201carmpits.\u201d Some species, such as grouse, ptarmigan and even snow buntings, plunge into soft snow and use body heat to warm up their \u201ccave.\u201d On nights when temperatures are exceptionally frigid, some small birds will pack themselves into tree cavities. On one occasion, up to 50 titmice were found huddled in a ball-like mass in a cavity.<\/p>\n

So don\u2019t worry about the birds in winter. Nature has provided them with an array of adaptations. After all, if they couldn\u2019t handle it, they wouldn’t stay.<\/p>\n

\n

\"\"<\/p>\n

 <\/p>\n

Reprinted from <\/em>Canadian Wildlife magazine. Get more information or subscribe now<\/a>! Now on newsstands! Or, get your digital edition today<\/a>! <\/em>Preview digital copy \u00bb<\/a><\/em><\/p>\n<\/div>\n

 <\/p>\n

——————————————-<\/p>\n

Dans le froid intense<\/h2>\n

\"bio_jf2016_birding\"<\/strong><\/p>\n

Certaines des esp\u00e8ces d\u2019oiseaux les plus robustes affrontent l\u2019hiver ici m\u00eame. Mais elles ont quelques trucs dans leur manche.<\/strong><\/p>\n

Si vous deviez passer du temps dehors, sans v\u00eatements, dans n\u2019importe quelle ville canadienne en janvier ou en f\u00e9vrier, votre esp\u00e9rance de survie serait passablement \u00e9court\u00e9e. Nous avons donc besoin de manteaux isol\u00e9s, de mitaines et de bottes appropri\u00e9es. Mais comment font les oiseaux? Bon nombre d\u2019entre eux ne migrent pas dans le sud en hiver, alors comment supportent-ils le temps froid?<\/p>\n

Effectivement, les oiseaux profitent d\u2019un nombre \u00e9tonnant d\u2019adaptations physiologiques et comportementales pour survivre aux conditions les plus froides. Et cela commence par leur caract\u00e9ristique la plus exclusive : les plumes. Vous ne trouverez pas mieux en fait d\u2019isolant l\u00e9ger et naturel.<\/p>\n

S\u2019HABILLER DE PLUSIEURS COUCHES<\/strong> : de la m\u00eame mani\u00e8re que nous ajoutons une ou deux couches suppl\u00e9mentaires de v\u00eatements pour nous prot\u00e9ger du froid, certains oiseaux am\u00e9liorent leur capacit\u00e9 isolante lors de la mue en ajoutant de nouvelles \u00e9paisseurs \u00e0 leur plumage. Certains moineaux vivant dans des r\u00e9gions tr\u00e8s froides augmentent le poids de leur plumage de plus de 70 % entre l\u2019\u00e9t\u00e9 et l\u2019hiver.<\/p>\n

Vous avez certainement d\u00e9j\u00e0 observ\u00e9 un oiseau par une journ\u00e9e tr\u00e8s froide gonfler son plumage jusqu\u2019\u00e0 ressembler \u00e0 une petite duveteuse? L\u2019oiseau est tout simplement en train d\u2019ajuster ses plumes pour cr\u00e9er des pochettes d\u2019air chaud qui augmenteront le pouvoir isolant de son plumage. Vous appliquez le m\u00eame principe au moment de choisir un manteau d\u2019hiver : vous voulez que l\u2019isolant ne soit pas trop serr\u00e9 pour permettre \u00e0 votre corps de chauffer l\u2019air captif et ainsi cr\u00e9er une autre couche isolante.<\/p>\n

RAFFIN\u00c9S JUSQUE DANS LES PIEDS<\/strong> : mais qu\u2019en est-il des canards et des oies qui passent des heures \u00e0 barboter dans de l\u2019eau juste au-dessus du point de cong\u00e9lation? Leur plumage est imperm\u00e9able, mais qu\u2019est-ce qui emp\u00eache leurs pattes et leurs pieds de geler, ce qui provoquerait la gangr\u00e8ne?<\/p>\n

D\u2019abord, ils limitent la circulation dans leurs pieds afin de ne conserver qu\u2019un minimum de sang dans le r\u00e9seau des capillaires. Un d\u00e9bit juste suffisant pour garder en vie les cellules des tissus. En second lieu, gr\u00e2ce \u00e0 un syst\u00e8me de r\u00e9cup\u00e9ration de chaleur, le sang art\u00e9riel qui coule vers les pieds r\u00e9chauffe le sang veineux plus froid qui revient des extr\u00e9mit\u00e9s. Ces m\u00e9canismes emp\u00eachent que la chaleur de l\u2019oiseau soit dissip\u00e9e dans le milieu ext\u00e9rieur.<\/p>\n

Les oiseaux connaissent un autre truc qui nous est inaccessible. Quand la nuit est particuli\u00e8rement froide, ils sont capables d\u2019abaisser la temp\u00e9rature de leur corps de quelques degr\u00e9s pour conserver de l\u2019\u00e9nergie. Si un oiseau a froid, il tend les muscles de sa poitrine et se met \u00e0 trembler pour g\u00e9n\u00e9rer de la chaleur. Contrairement \u00e0 chez nous, ce tremblement est quasiment imperceptible.<\/p>\n

MODIFICATION DES COMPORTEMENTS<\/strong> : les oiseaux sont aussi capables d\u2019ajuster leurs comportements pour s\u2019adapter \u00e0 l\u2019hiver. Par temps tr\u00e8s froid, les oiseaux terrestres favorisent des secteurs \u00e0 l\u2019abri du vent pour se nourrir et pour percher. La sauvagine cache souvent sa t\u00eate sous \u00ab son aisselle \u00bb, c\u2019est-\u00e0-dire sous son aile. Certaines esp\u00e8ces comme les t\u00e9tras, les lagop\u00e8des et les plectrophanes des neiges plongent dans la neige molle et se r\u00e9chauffent une \u00ab caverne \u00bb. Quand les temp\u00e9ratures sont exceptionnellement glaciales, certains petits oiseaux se rassemblent en groupes compacts dans des cavit\u00e9s dans les arbres. On a d\u00e9j\u00e0 trouv\u00e9 une cinquantaine de m\u00e9sanges bicolores blotties en une grosse boule dans le creux d\u2019un arbre.<\/p>\n

Alors, ne vous inqui\u00e9tez pas pour les oiseaux en hiver. La nature leur a fourni un \u00e9ventail de moyens d\u2019adaptation. Apr\u00e8s tout, s\u2019ils \u00e9taient incapables de supporter l\u2019hiver, ils ne resteraient pas ici.<\/p>\n

\n

\"\"<\/p>\n

Ce suppl\u00e9ment se rapporte au magazine <\/em>Biosph\u00e8re. Pour plus de renseignements ou pour vous abonner, cliquez ici<\/a>.<\/em><\/p>\n<\/div>\n

 <\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Some of Canada\u2019s hardier bird species brave the winter right here at home. They have some good tricks up their sleeves. If you stood outside in just about any Canadian…<\/div>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[633],"tags":[591],"class_list":["post-2376","post","type-post","status-publish","format-standard","hentry","category-canadian-wildlife","tag-wild-about-birds"],"_links":{"self":[{"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/posts\/2376","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/comments?post=2376"}],"version-history":[{"count":3,"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/posts\/2376\/revisions"}],"predecessor-version":[{"id":2381,"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/posts\/2376\/revisions\/2381"}],"wp:attachment":[{"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/media?parent=2376"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/categories?post=2376"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.cwf-fcf.org\/index.php\/wp-json\/wp\/v2\/tags?post=2376"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}