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Author Topic: The Hornby Island Eagles' Diet: Opossum  (Read 28031 times)
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madrona
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« on: March 15, 2010, 01:16:46 AM »

Opossums on Hornby Island

Nestcam watchers during the 2009 nesting season had a few surprises with regard to prey items brought to the nest.  We saw and heard the midshipmen fish (See Low Tide at Hornby article on Website's Webcam page) that were regularly flown in, but we also saw another creature brought to the nest when fishing was poor—a marsupial!  The non-indigenous Virginia opossum Didelphis virginiana was fed to the eaglet chicks when fish were scarce.

Opossums were introduced to Hornby in the late 1980s and have flourished there since, as there are few natural predators for these nocturnal creatures. An adult female can produce two or more litters in a breeding season, each usually of six to ten or more young. Read here for more specific facts and information.    
 
The opossum is not a welcome Hornby resident because, like many introduced species elsewhere, it has become a threat to local flora and fauna.  Other native animals, from small mammals to amphibians, insects, birds and their eggs as well as native fruits and plants are threatened by this introduced species. Because of this risk to native species, and a rapid increase in their numbers, opossums have been regularly trapped on Hornby Island, and the remains of some of these creatures show up in the nest from time to time.  

Last spring, a local resident posting in the Hornby chatroom, told how an opossum had killed one of her hens, so she left the remains of the hen on a rock for the eagles. Within a day or so, the remains of the offending opossum, which was successfully trapped, were also placed on the rock.  It did not take long before Mom came to investigate.  
 

Shortly afterwards, sizable pieces of this unfortunate opossum, nicknamed ‘Wilson’ by cam watchers, were brought into the nest.


It was quite a struggle for Mom Hornby to lift this carcass.  Eventually she was able to take a portion to the nest and immediately fed some to the eaglet. The remainder was stashed away in the nest and provided many additional feedings when fish were scarce.

Judging by the skulls visible from time to time in the nest, there were at least four opossum deliveries during the 2009 nesting season. These unwelcome ‘aliens’ have therefore played a role in helping our Hornby eagles to thrive.  

Below is a picture of opossum bones tossed out of the nest by Darian when he climbed to the nest to clean the camera (October 10, 2009).



More recently, since observing the nestcam again after the eagles’ return from their short fall visit to the salmon spawning rivers, we have again seen how the Hornby Island opossums feature in the diet of this eagle pair.
  

What is this in the nest? - Nov 9 09


We soon discovered that it was opossum remains

Doug had seen Mom Hornby eating an opossum on the shore on November 8 09 and when the cam went live the following day, we saw some of those remains being eaten by both eagles leaving only a skeleton for our viewing pleasure!


Mom is clearly interested in snacking on the carcass - Nov 9 09


Both Mom and Dad come back for more - Nov 10 09


As darkness falls Dad can be seen and heard, crunching on the skeletal remains - Nov 10 09
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      rather than what we are separate from. - Terry Tempest Williams
NancyM
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« Post / Reply #1 on: June 15, 2011, 10:13:54 AM »

A very interesting and readable article from the New York Times about opossums, published June 2011.

http://www.nytimes.com/2011/06/14/science/14angier.html?_r=1&ref=science
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