Wildwood Tracker — ruling 1

If you don't control another non-Human creature immediately after Wildwood Tracker attacks or blocks, its ability doesn't trigger at all. If you don't control one as the ability resolves, the ability does nothing. It doesn't matter whether you control a non-Human creature in between those times, or whether you still control one later in the turn.

Wildwood Tracker : règles, fonctionnement et interactions (MTG)

Wildwood Tracker is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Whenever this creature attacks or blocks, if you control another non-Human creature, this creature gets +1/+1 until end of turn.

How it works : Wildwood Tracker

Original English text — Wizards of the Coast / Scryfall

#1October 4, 2019· Wizards of the Coast
If you don't control another non-Human creature immediately after Wildwood Tracker attacks or blocks, its ability doesn't trigger at all. If you don't control one as the ability resolves, the ability does nothing. It doesn't matter whether you control a non-Human creature in between those times, or whether you still control one later in the turn.
No other card is named in this ruling.