There is no overriding international organisation that dictates to them. But they do confer with each other and usually adopt each others' protocols. But not rigidly.
Well, this is part true, part wrong. What species make up a genus or what populations make up a species is left to the taxonomists to decide, so two taxonomic committees could indeed adopt different protocols and take different decisions regarding this point. But the technical aspects of how to apply the names once you have decided which groups deserve one (= nomenclature, this includes gender agreement) are dictated very rigidly by the International Code of Zoological Nomenclature. Neither the AOU nor the BOU would knowingly deviate from what the Code dictates. (But of course mistakes can happen.)
Actually BOU does follow the masc./fem. thing, hence we now have e.g. Delichon urbicum not D. urbica. In the case of Peocile, this is a nonsense word, like Parus, and while the original author believed it had a gender, and AOU have followed this, BOU believe that there is no evidence that the word has any gender and therefore believe that maintaining the staus quo is preferable.
Poecile derives from a classical Greek noun ('poikilê'), that was adopted by classical Latin as 'poecile'. Both the original Greek version and its Latin-adopted version are definitely feminine, so its gender makes absolutely no doubt.
In fact, it's Delichon that is the nonsense word, here: this name is an anagram (of Greek 'chelidôn' = swallow), hence not an existing word. There are (rather arbitrary) rules in the Code that determine the gender of names in such cases - in the present case, this name is deemed neuter because it ends in -on, which is the default ending of neuter nouns in Greek. Chelidôn, however, in Greek, is feminine.
Hence this masculine/feminine thing; when Black-capped Chickadee changed from Parus to Poecile, the atricapillus had to change to atricapilla to reflect the change in gender of the genus name.
The story is much more complicated than this.
The genus Parus was split by the AOU Checklist Committee in 1997 and, at that time, they did exactly the same mistake as the BOURC-TSC: Poecile atricapillus, Poecile hudsonicus, Poecile cinctus.
(
http://elibrary.unm.edu/sora/Auk/v114n03/p0542-p0552.pdf , p547.)
In 2000, they corrected this to Poecile atricapilla, Poecile hudsonica, Poecile cincta.
(
http://www.aou.org/checklist/suppl/AOU_checklist_suppl_42.pdf , p.852 - note also the explicit reference to Poecile montana there.)
However by doing this, they had in fact been a step too far - only adjectival Latin or latinised species names must agree in gender with the genus name, and atricapillus (meaning 'black head', not 'black-headed') is actually not adjectival. So, in 2003, they had to change this name back again to Poecile atricapillus.
(
http://www.aou.org/checklist/suppl/AOU_checklist_suppl_44.pdf , p.928.)
Corrections are not necessarily much faster on the other side of the pond...
If scientific names were numbered instead of named (e.g. Poecile genus = 1, Marsh Tit = 1.1, Willow Tit = 1.2, British Willow Tit = 1.2.1, Scandinavian Willow Tit = 1.2.2) that still conveys all the same information on relatedness.
...Except that Poecile would definitely NOT be genus 1, but instead something like genus 3225 - a number that would presumably change every time you split or lump any other group appearing before it in the sequence... Same problem for the species: 3225.1, in a system recognising chickadees as distinct from other tits would have to be something like 3220.33 in a system grouping all the tits together...
This would perhaps convey relationships, but retrieving information with such a system would be nearly impossible.
Willow Tit's range is so large that it covers pretty much all elevations, showing no association with any (except avoiding very high elevations - high mountains!).
The difference does not apply 'across the range' of the species, actually, but only in its southernmost populations. In Europe, this concerns the montanus subspecies group, AKA 'Alpine Tit', which is therefore indeed aptly named. This group is found in the Alps, Carpathians, Appenines, Rhodopes, etc...; just compare the ranges of Willow and Marsh Tits in these regions.
