5️⃣ As always, thanks to funding sources, (Bluesky-less) co-authors, especially to Kyle McVea, who did a lot of the brain work here as part of his 4th year Honours thesis (!) last year in the Phillmore Lab 🥳
(/end of thread)
4️⃣ Now what might be driving this change (especially in X)? Or is this something specific to chickadees? Be sure to check out the paper for some (preliminary) thoughts...plus plenty of other interesting tidbits! 🧠🔬🐥
onlinelibrary.wiley.com/doi/10.1111/...
3️⃣ Now we are definitely NOT the first to show some vocal control system growth occurring pre-reproductive maturation (especially in wild birds!)
But, this is the first evidence showing pre-breeding changes in X, as well as this interesting X➡️HVC pattern to springtime growth. 🤔
2️⃣ On the other hand, HVC (another key player in the vocal control system) does seem to need some degree of HPG axis upregulation/input before its springtime growth, as HVC *does* differ between male chickadees captured in early spring vs. late spring. 🐣🧠
The main takeaways:
1️⃣ In black-capped chickadees, vocal control nucleus Area X is already at maximum (=breeding) size BEFORE the onset of physiological breeding condition 🪺
X does not differ between male birds captured in early spring (=small gonads, low T) & late spring (=large gonads, high T)