Just yesterday I was discussing our good fortune that in 7 years of live cams on several nests we had not witnessed the death of a chick directly. I was relating the difference between wilderness eagles, who seldom raise more than one young per nest, to our incredibly productive urban and suburban eagles who nearly average two young per nest. Town eagles are generally much more productive than wilderness eagles. Dr. Scott Ford, a DVM and eagle specialist, and I were discussing over lunch - after just passing Delta 2 nest - how our cams had been reflective of the ground data I had collected for years. The urban/suburban eagles simply have more food available it appears. But our discussion went to the next prophetic discussion: What is the quality of the urban/suburban food?
Then at 6:00 AM this morning (June 1, 2012) I got an early call from one of our stalwart followers, Judy/JKR, that one of the Delta 2 chicks had just died this morning. When everybody went to sleep last night he was fine – at dawn he suddenly went feet up! While a few days back this bird had shown a possible problem with a stick/bone/or bulge in its crop, the bird continued to poop and eat and seemed to be getting over the possible problem. Then after appearing totally well for a day it is now dead.
We will not be climbing up the nest to retrieve the dead young as this would, almost certainly by my data, insure the adults abandoning the nest for next year, so unless the carcass falls we will not have a chance for an autopsy. In the meantime it will be up to speculation -- and I suspect there will be a lot of it! My two best guesses are:
#1 Possibility of a follow up infection from that which was protruding in the crop earlier.
#2 The eaglet received a poisoned contaminated item of food.
The #1 option of a delayed infection while possible is less likely in my opinion due to the suddenness of the death and the regularity of the eaglet feeding and passing food in the last two days. The crop extension could simply have been the full leg or wing bone of some adult gull or duck or even the leg bone of an adult rabbit. I suspect an adult prey item would digest less quickly and could have remained apparent for a few days.
The poisoning option seems most likely and yet surprisingly this has not been as apparent over the years as I would have suspected. Our urban eagles in Delta have some of the best natural and modified eagle habitat in the world -- from the Boundary Bay and Roberts Bank intertidal shallows to the intensively ditched farmland abounding with fish, muskrats, rats, water fowl etc. Yet on top of this incredible natural-wild food supply, eagles are also basically scavengers and they readily accept road kills and the parallel of farm killed refuse. This latter can consist of poisoned rats and voles. The dead animals or sick and dazed animals are ready prey to our eagles. The adjacent farmland has many poison control programs to get rid of vole and muskrat predation that prey on the roots of blueberry plants. Was a poison used that could in turn be transmitted as a killer to the scavengers that eat the dying rodents? This is not allowed and we will attempt to track this down. There are poisons that will kill a mammal and then not kill the scavenger eating the poisoned vermin.
Did our parent eagles pick up something from one of the two nearby refuse dumps? Possibly. Again, poisons are not supposed to be dumped! But this is hard to track. At the other end of options it must also be remembered that for a million years eagles have been scavenging rotting and dying creatures. The eagles are part of nature's garbage disposal system. Most of the scavenging birds, like the corvids, vultures and eagles, have developed an incredible immunity to putrid-based diseases and various natural toxins. They could not have continued as nature's cleanup crew and not have developed this immunity. But, and it is a serious but, we humans have perfected our tools of weeding out vermin. Part of evolving that "perfected targeting" is our ability to develop poisons that affect only one group of animals and not another. Perhaps, if poisoning was the culprit here, we have not effectively done our job.
The next interesting challenge will be to learn how this 6 – 8 pound carcass is to disappear. Wow! Triumph and awe inspiring behavioral events have high-lighted the live cam experience. Sharing the tragedy may not be to every ones taste. If the bird falls, that is if you see it missing in the nest, I would like to be called instantly as I will have an autopsy done.
Please do not call unless the dead eaglet has fallen from the nest. Instead you may contact me through firstname.lastname@example.org