A pretty bird and definitely one of the British examples. I have to still puzzle in my mind about dating the screaming eagles of this variety. We have to keep in mind that blades could be from stock and surplus mounted for decades. Very true in this case, as I suspect the pommel and grip speak to the late 1830s. The guard a decade earlier, as well as the mixed white etch and b&g panels.
At any rate, I would place it between 1836 and the early 1840s. The Ames pommel and ferrule quite distinctly different than the English examples. The unstopped fullers were phased out in the 1840s, so we have to consider other factors after the 1830s. I had recently acquired an Ames example I place to the 1840s by virtue of the etching pattern. The blade of the later pattern I have file examples of later Ames sabers with ricassos as well, so the change reflects production after the adoption of 1840s regulation patterns of such as infantry and artillery swords.
This one definitely militia, as the earlier regulation infantry spadroons were silver was, this one a gilt hilt.
In Iding an Ames of this type, start with the pommel collar and ferrule. Then move to the blade etching. I know of no Ames examples of this bird with blue&gilt.
An edit to mention that you will not find your's in the early Mowbray title but you might find the British example in The Medicus Collection book put together by Norm Flayderman and Stuart (the son) Mowbray. While lacking in detail in depth, probably the best single flash card deck of American swords.
The eagles from Ames best represented in Hamilton's history of Ames. There rare still some copies of that book at original retail but they are drying up. Occasionally found on Ebay but I know of one dealer that may syill have some (as well as Don Furr's American sword book) You can reach me at gcleeton@gmailcom or PM here but email works better. I can send the dealer information if interested. I don't want to just link it here and be frowned upon
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Cheers
GC