WHITE WINGED CHOUGHS – Brenda

The  White  Winged Chough [pronounced chuff and sometimes known as Black Jay  locally]  is  still fairly common in our area although we see them less now than we used to, perhaps they are having to enlarge their food gathering areas so take longer to complete the circuits. A  Chough is a large black bird that has a white under-wing patch that is  only visible  in  flight or when the bird is displaying. Another  feature  is  the down curved bill and the red eye of birds over 4 years old.

In over 20 years I have only received one or two young Choughs in the shelter for care. Once the bird has been checked to ensure it is healthy and not injured the only way to ensure its survival is to return it to its family or find another group and persuade them to take the young bird under their wing, so to speak. It is rare the offer of a new member for the family is rejected, the young birds are usually quickly accepted into the new group.

Choughs have a very interesting and tough life, an article published in the Australian  Nature magazine several years ago  gave us a peek into the lives of these large, gregarious birds.

Life for a Chough is particularly hard and a pair simply  cannot  breed without help. This explains why Choughs are found in groups of 4 to 20  birds during the breeding season. When not breeding more than one group of Choughs’ may come together to a regular food source. A  lot  of their food comes from beneath the ground and  therefore  the  birds spend  a lot of time digging holes, some up to 20cm deep. Digging uses a  lot of  time and energy and old birds learn that digging around grass tussocks  is more  likely  to  yield  a  beetle larvae  or  something  else  edible.  More importantly,  mature  birds learn when to give up digging in  an  unproductive patch whereas young birds will continue to dig and end up with nothing for all the energy expended. Choughs are interesting to watch as they search for food on the forest  floor, often they are so engrossed in their search that they don’t notice an observer and  will  carry on tossing leaf litter from side to side in search  of  their elusive meal.

Choughs  build a large bowl shaped mud nest approximately 35cm  across.  Four eggs that take 3 weeks to hatch are laid by the breeding pair, the young  then take  4  weeks to fledge; young are fed for up to 8 months.  Many  songbirds  only  look after their young for twice the  nesting  period  but Choughs  continue  their support for up to 8 times the  nesting  period.  The young  must  have  this  support  until  they  master  their  basic   survival techniques. The  time and experience needed to find food means that one pair alone  cannot supply  all that is required to feed a clutch of young.

Of the  few  recorded attempts  by  single pairs of Choughs to nest they have lost  their  young  to starvation. The minimum viable group size is 4 and even so these 4 will  only raise  one  chick. Each additional helper increases the chances of  a  chicks survival to where a group of 10+ can occasionally raise all 4 chicks.

The offspring from previous years help in all instances from building the nest through to caring for the fledglings.

Neighbouring  groups  of  birds  will sometimes  destroy  each  others  nests, intruders peck at the foundations of the nest in an attempt to dislodge it, if this is unsuccessful they will destroy the eggs.

If  the  nest  is destroyed it often stops a group from  breeding  again  that season  as the mud needed to rebuild may not be available at the time.  These delaying  tactics reduce the competition for food from groups close by  giving the intruders young a better chance of survival.

Kidnapping also occurs amongst Choughs with large groups ganging up on smaller groups. Some birds from a large group will engage members of a smaller  group in  battle  whilst others approach a juvenile and attempt to entice  it  away using  a tail-wave and wing-wave maneouvre. If the enticement  is  successful the  young bird is fed immediately and within a short period it acts as if  it has  always been with the group. Young Choughs appear to be  easily  confused and  perhaps have not developed a bonding with their group so early in  life. Kidnapping  doesn’t  occur later than a month or so after  fledging  when  the birds have more than likely bonded to their home group. A  group  of birds willing to feed someone elses offspring for 7  months  must surely be an indication just how desperate a group is to gain another  helper. Does this show how hard life is for a Chough?

DNA  fingerprinting has found that when the structure of  a  group  of Choughs is stable one pair dominates the reproduction year after year but when deaths  in  the  family  have fragmented  groups,  helpers  try  out  different combinations  with others that they meet in their travels until they work  out who is likely to produce the best offspring.

Chough groups are highly inbred, often the breeding pairs are closely related. Disasters such as droughts that cause members of groups to die may well be the way new blood is brought into family groups.

Chough's Mud Nest

 

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