How na­ture equips wild birds for win­ter

How is it that win­ter's bru­tal cold doesn't ap­pear to faze them? Birds have the high­est body tem­per­a­ture in the an­i­mal world.

Alberta Gardener Magazine - - Contents - By Sher­rie Ver­sluis

How do they do it? How do wild birds sur­vive in the dead cold of win­ter? We all know as hu­mans that when the ther­mome­ter hits mi­nus 20 or colder we hurry from the car to the house. Even when we are decked out in thick, down­filled coats with toques and mitts, it is still bit­ter and un­bear­able. When the wind chill kicks in those tem­per­a­tures can even be life threat­en­ing. Yet, wild birds carry on each day seem­ingly un­both­ered by the bru­tal­ity of win­ter. What do they have that we don't?

Birds have the high­est body tem­per­a­ture in the an­i­mal world, rang­ing from 105 to 112 de­grees Fahren­heit com­pared to about 98 de­grees for hu­mans. It re­quires a lot of calo­ries to main­tain these tem­per­a­tures in win­ter. Prepa­ra­tions for the cold sea­son be­gin in the fall when wild birds start to build up fat re­serves. At that time of year, food sources are plen­ti­ful, as many plants have gone to seed, and birds will eat ex­ces­sive amounts. This ex­tra layer of fat serves as in­su­la­tion and can pro­vide the ex­tra en­ergy needed to main­tain their body tem­per­a­ture.

Down for the win­ter

Feath­ers are ob­vi­ously the sta­ple in equip­ping birds to stay warm. In fact, wild birds will grow about a thou­sand new feath­ers for win­ter! These are mostly down feath­ers which are closer to the skin.

You may wit­ness birds shiv­er­ing and puffed out in win­ter but, they are not do­ing this be­cause they are cold. It’s one way for them to pro­duce more body heat. The tech­nique is only used in the cold­est of weather as it re­quires a lot of en­ergy and calo­ries. The exterior feath­ers pro­vide a source of wa­ter

and wind-proof­ing as well as in­su­la­tion.

All birds have an oil gland lo­cated at the base of their tails. You may some­times see a bird rub­bing its head from the tail up­wards. This preen­ing is how birds spread that oil through­out their feath­ers. Prop­erly preened feath­ers are im­per­a­tive for wild birds es­pe­cially in win­ter.

I have been asked many times how birds’ skinny lit­tle legs don't freeze off. Their legs are de­signed with very hard scales that re­duce heat loss. Birds can also con­trol the tem­per­a­ture of their legs sep­a­rately from the rest of their body by re­strict­ing blood flow. Some­times birds will tuck their head un­der their wing and crouch down to keep their faces and legs warm. On sunny win­ter days, birds take full ad­van­tage of the sun's warm touch. They will find a perch in direct sun­light and warm their bod­ies to con­serve calo­ries.

The most sur­pris­ing thing about wild birds in win­ter is how they make it through the long, se­verely cold nights. Some birds, like chick­adees and nuthatches, will roost to­gether in small groups in­side a cav­ity. They may find a nat­u­ral tree cav­ity or a hu­man­pro­vided source like a bird­house or win­ter roost where they will share their body heat. I once saw a pic­ture of about 16 chick­adees packed in­side a roost like a lit­tle puz­zle.

Another skill birds use is to go into a state of tor­por dur­ing the night. Tor­por is a state of low­ered me­tab­o­lism where they re­duce their body heat by about 50 de­grees. It is for them an im­por­tant way to re­duce and con­serve calo­ries, but this can be dan­ger­ous. Their re­ac­tion time while in this state is very slow, mak­ing them vul­ner­a­ble to at­tack by preda­tors.

Here are some tips on help­ing wild birds ob­tain a bit of an edge on win­ter. Pro­vide black oil sun­flower as a sta­ple food. This seed is very high in fat and ap­peals to all birds in win­ter. You can also con­sider shelled sun­flower, which makes things even eas­ier for them. A qual­ity suet is an ex­cel­lent source of fat, en­ergy and calo­ries, and a great favourite of wood­peck­ers and nuthatches in par­tic­u­lar.

Put out qual­ity food

Find­ing wa­ter is ex­tremely im­por­tant for birds when they’re ready for preen­ing. Wa­ter is used to wet the oil gland, mak­ing it eas­ier to dis­perse the oil through­out their body. It also as­sists in di­ges­tion in the cold. Heated bird­baths are a fab­u­lous way to of­fer birds wa­ter. Don't worry, though. You won’t see the birds bathing the way they do in sum­mer. Another of­fer­ing they ap­pre­ci­ate is a bird­house. A bird­house left out­doors will pro­vide shel­ter for birds to roost in dur­ing the night.

Wild birds are al­ways able to find nat­u­ral foods, and so they aren’t de­pen­dent on feed­ing sta­tions. But life be­comes much eas­ier for them if you keep your feed­ers filled with of­fer­ings of high-qual­ity foods.

In re­turn, you will be treated to the beauty and an­tics of wild birds all sea­son long. This will keep your spir­its as bright and cheer­ful as the birds them­selves. G

Sher­rie Ver­sluis owns The Pre­ferred Perch, at 204-257-3724.

Be kind to our feath­ered friends this win­ter. Put up a bird­feeder and en­joy the feath­ered frenzy as they stop by for a bite.

Sun­flower seeds are an ex­cel­lent win­ter treat. Many birds grow more down feath­ers for the win­ter months to help cope with the win­ter chill. Nan­ny­berry, moun­tain ash or Siberian crabap­ple are hardy shrubs carry their berries into the win­ter that of­fer food for the birds and colour for the gar­den.

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