Just some background before breaking into the good news.
Avian Pox (AP) is a slow-developing bird disease caused by a virus
belonging to a subgroup of poxviruses, the Avipoxvirus. There is no cure. AP is an international problem for every species of bird. One of the first ways of noticing that a bird has AP is the appearance of lesions on the non-feathered areas such as the face, feet, mouth and beak area, as well as the upper respiratory tract. Sometimes these lesions resemble warts and other times they look like blisters. Birds catch AP from mosquitoes, by eating infected prey, or being in contact with other birds or surfaces contaminated by AP. Researchers believe that the disease ranges from mild to severe but that it is rarely fatal (Wrobel et al. 2016). Birds are more likely to die if the virus impacts its respiratory tract. Additionally, secondary infections can be fatal. The USFWS found that the number of cases occurs less frequently in dry climates while the highest number are in hot and humid climates such as Florida and Louisiana. Those climatic conditions are perfect environments for mosquitoes.
One of the biggest issues is that there has not been a large study of Avian Pox in the Bald Eagle population. The study conducted by Wrobel et al found that the frequency of raptors having Avian Pox is far greater than the outward signs such as lesions would suggest. Of the 142 raptor specimens in their research project, ten were Bald Eagles. Of those, 30% had antibodies related to Avian Pox. The researchers admit that their study, which focused on urban and suburban raptors admitted to a Central Illinois clinic, had more small raptors such as Kestrels and Barred Owls. What they did learn is that 50% of all of the raptors had antibodies indicating that they had, at one time, Avian Pox or Conjunctivitis (effects the eyes such as we have seen on SWFL E17 and E18). That is a far higher amount than the scientists expected and their results indicate that the number of raptors exposed to either or both AP and Conjunctivitis is far more prevalent than anticipated. The researchers said that the free living or wild birds in the study indicate that most raptors are able to ‘mount a full adaptive immune response against these pathogens’ (291). This, of course, is excellent news for our raptors if it is correct.
As you are aware, if you have been reading my column or following the NEFL Eagle Nest, the eaglet N24 was observed by individuals of the American Eagle Federation to have Avian Pox on 20 February. On 27 February, the lesions were noticed by many people. Some posted videos expressing concern on YouTube such as Lady Hawk. I mounted a campaign in support of N24 in case an intervention became absolutely necessary. Neither Avian Pox or Conjunctivitis are caused directly by humans. The eaglets at the SWFL Nest, E17 and E18, had Conjunctivitis and were treated by CROW. Their eyes fully healed and they were returned to the nest. It was hoped that little N24 could receive similar help should it respiratory system become compromised.
The good news today, 2 March 2021, is that N24 has a very good appetite. N24 cast a pellet at 6:32 am. It is now 6:40 pm on the nest. There have been at least two feedings. (Pantry was bare til first feeding) The first was around 10:36. Samson brought a fish and started feeding N24. Gabby took over at 10:50 with Samson leaving and returning with another fish. The parents have been very attentive to the little one over the past few days. And, yes, of course. They knew he was sick! All parents know when their kids are not feeling well.
The second feeding began around 4:21pm.
A third feeding began around 5:46. A few minutes earlier Gabby offered fish but N24 did not appear interested in getting out of the egg cup to eat. He is leaning on ‘the egg’. Around 5:47 Gabby begins feeding the eaglet stretching to reach it in the nest. N24 has a large crop.
I can see no further lesions on N24’s face or mouth area. In fact, it appears that the lesion on the left of the face is reduced. Can you see me jumping up and down?
I am not a vet or a wildlife rehabber. Every research paper that I can find on AP indicates that the lesions can persist for 1-4 weeks. It has been ten days since the first lesions were noticed. I am hopeful that N24’s immune system is really working to heal this lovely ‘cutie pie’ whose permanent name will be Uno, Scout, Kendi, Storm, Journey, or Legacy. Voting for AEF members ends on March 5.
Just to give you a laugh and to thank you for joining me today, ‘the egg’ became quite an amusement today. N24 leaned on it for a feeding, brooded it in the nest while eating, and even Gabby wasn’t sure what to do with it all the time.
References:
E. Wrobel et al, ‘Seroprevalence of Avian Pox and Mycoplasma Gallisepticum in Raptors in Central Illinois’, The Journal of Raptor Research 50 (3): 289-294.
Field Guide to Wildlife Diseases: General Field Procedure and Disease of Migratory Birds, US Department of the Interior, Fish and Wildlife Service, Resource Publication 167 (1987): 135-141.