Adult Bald Eagle

[smittyone@cox.net]

Seen last week at DeSoto NWR near Missouri Valley, Iowa.  I know this is a Bald Eagle.  I also know Bald Eagles reach adulthood and attain their fully white head and tail feathers at around 5 years old.  Considering that, I'd say this eagle is about 4 years old.  What would be the correct way to call this eagle--immature, sub-adult, other?

[BirdNrd]

Definitely Bald Eagle

[smittyone@cox.net]

14 minutes ago, BirdNrd said:

Definitely Bald Eagle

Thank you.  But that wasn't the question I asked.

[Sneat]

I believe you would call this a sub-adult Bald Eagle. @akandula or @The Bird Nuts, what are your opinions?

[Benjamin]

From hawkwatch.org:

Quote

Also, a 1st-year bird (birding terms) is what most people call a "juvenile." So, lets distinguish between "juvenile" and "immature" since those two terms are often interchanged or confused for each other. "Juvenile" is a bird in its first plumage as we mentioned, but the term "immature" defines a bird that is any age other than adult. So, "immature" is a broad term that includes or lumps juvenile and sub-adult plumages. A juvenile is an immature bird, but an immature bird is not necessarily a juvenile. The term "sub-adult" describes a plumage that occurs after the juvenile (1st-year) plumage but before the adult plumage. Birds that take several years to acquire their adult plumage, such as eagles, Swainson's Hawks, White-tailed Hawks, and several others, have one or a few sub-adult plumages.

So I'd say this is an immature bird, but more specifically a 4th year subadult. Also, it's important to note that a 4th year bird is not the same as a bird that is 4 years old. The difference might seem semantic, but a bird becomes a n-year bird when it starts it's n-th calendar year, while a bird only becomes n years old when it passes the date of hatching the n-th time.

Edited May 25, 2020 by Benjamin

[BirdNrd]

3 minutes ago, Sneat said:

I believe you would call this a sub-adult Bald Eagle. @akandula or @The Bird Nuts, what are your opinions?

Definitely not immature, so I would call it sub-adult

[Benjamin]

Oh and when I say the difference between a 4th year and 4 year old bird might seem semantic, I mean it definitely is semantic. But that's the entire point of this post, no? ?

[smittyone@cox.net]

Thank you very much.  That was precisely the answer I was seeking.

 

[The Bird Nuts]

13 minutes ago, BirdNrd said:

Definitely not immature, so I would call it sub-adult

Sub-adult is not mature, so it is immature.  However, this bird is NOT a juvenile, which I think is what you meant to say.

[smittyone@cox.net]

So let's muddy the waters a bit, shall we?  I learned a while back to stop calling Bald Eagles that weren't yet adults all as juveniles.  I reserve the juvenile moniker for when they haven't fledged yet.  I'm probably wrong in doing that.  But when does an eagle stop being an eaglet?  When it's no longer fuzzy and gets it's flight feathers?  I'm fairly confident that I can age an eagle by plumage as 2, 3, or 4 years old, and will start calling 4 year olds as sub-adults.  By my logic, if it's almost an adult, it's a sub-adult.  Not gunna call 'em teenagers.  I'm not trying to become an expert in all things eagle.  But when I post a bird image online somewhere, I like to be as accurate as possible as to what I call it.  Age, sex, breeding plumage, etc. 

 

[Benjamin]

I don't know that there's a good definition for what exactly an eaglet is, likely because in a scientific setting there are more precise words that would be used, i.e. nestling or fledgling, or simply denoting the age of the birds in days/weeks.

Just thinking about how the word would be used informally, it is probably best used while the eagle is a nestling, although it could perhaps also refer to a fledgling as well. I don't know that I would call an young eagle that is out of the nest and independant an eaglet, but fledglings tend to spend some time in the nest and are still somewhat reliant on their parents, so they fall somewhere in the middle here.

While doing research, it became clear that a lot of these words just really aren't used with consistency, which is a big problem because it causes confusion. For example, it seems that some literature (namely this) suggests that the word juvenile is purely plumage based, so any bird with its first molt of contour feathers should be considered a juvenile bird. This makes sense with the earlier definition of a bird within the first year in context of a large bird like an eagle, because most birds molt annually, however some smaller species might molt more than once and reach adult plumage or other immature plumages quicker than one year. It seems quite silly that a smaller bird could be considered a juvenile bird under several different plumages, so it's pretty logical to instead base the term juvenile purely on molt.

Edited May 25, 2020 by Benjamin

[smittyone@cox.net]

Now my brain hurts.  Thanks Benjamin.  Just kidding.  But this is a wealth of information that I'll have to look into further.  I was hoping for a simple answer, but as you pointed out, there really aren't any simple answers.  THIS is why I come to this site.

 

[Charlie Spencer]

I'm not fond of eaglet, owlet, gosling, or other terms specific to individual species or genera.  That's because they don't have any accuracy.  There are more species that lack these name than are that have them.  There aren't cardinalings or pelicanets; why have names for the young of some species and not others?

But I was up too late watching the race so maybe I'm just cranky.

Edited May 25, 2020 by Charlie Spencer

[insanityslave]

i was gonna try to 'tony' this thread, but i cant find the original site, so ill just upload the pdf. (see attached)

heres an excerpt (the whole article is definitely worth a read)

Immature – Unfortunately, this term has two accepted uses, so is not as precise a term as is “juvenile.” 1) The first use of this term is to indicate a bird that is in a plumage that is not wholly (or even partly) in juvenile plumage and not wholly (or even partly) in adult plumage. That is, the bird is somewhere betwixt the two plumage endpoints. Thus, this usage can be applied to birds of differing plumages, the first being a bird in the process of molting directly from juvenile plumage to adult plumage (e.g., Cooper’s Hawk and many other of the less-than-huge raptor species), the second to a bird that is in a distinct plumage intermediate between juvenile plumage and adult plumage (e.g., in most gull species, eagles, and many other long-lived species) (again, see Leukering 2010 and “sub-adult,” below) 2) The other accepted use of “immature” is to describe a bird seen well enough to know that it is not an adult, but not well enough to distinguish whether the bird is a juvenile or in some other non-adult plumage state (See Non-adult).

Non-adult – This term is, essentially, identical to the second type of usage of “immature.”

Sub-adult - This term is similar to the first type of usage of “immature,” but it is particularly used to describe a bird of a species with many distinct non-adult plumages, that is, not in juvenile plumage and not in adult plumage (e.g., first alternate, third basic; see Leukering 2010, Pyle 2008). Thus, this term is used especially to describe gulls and eagles.

bird plummage age terminalogy.pdf

[BirdNrd]

4 hours ago, The Bird Nuts said:

Sub-adult is not mature, so it is immature.  However, this bird is NOT a juvenile, which I think is what you meant to say.

Yes, that is what meant, sorry.

[Bird Brain]

This is why I just call then young'uns till they reach adulthood!!

[smittyone@cox.net]

Thanks for the info, and especially the PDF insanityslave.  Dumb question, but how do I save the PDF?

[insanityslave]

37 minutes ago, smittyone@cox.net said:

Thanks for the info, and especially the PDF insanityslave.  Dumb question, but how do I save the PDF?

not sure what happens for you, but when i click it it opens up in microsoft edge (my default for pdfs). from there i can save as/download.

[Benjamin]

@smittyone@cox.net open the PDF in whatever web browser you use, then press Ctrl+S on windows or Command+S on Mac. If you're on mobile there should be a button in a menu somewhere on the top, depending on which mobile browser you're using.

[smittyone@cox.net]

I use Chrome, but I figured it out.  Thanks everyone.  

[lonestranger]

I am like @Bird Brain and like to keep it simple and use generic terms that are still accurate enough to get the point across. For me, young'uns works for everything that isn't an adult starting right from minutes old chicks. From what I take from the discussion here, immature would be the same as calling them young'uns, right? Everything that isn't an adult is immature, right? Not that it really matters, I'll still probably call then young'uns or something similar. ? I've seen the reaction of some members when the wrong term is used to describe stages of a birds life, and don't want to set myself up to get trapped in the world of word semantics.