Why are zephyr hawks and river drakes both level 3?

Both zephyr hawks and river drakes are level 3 creatures. This seems insane.

Zephyr hawks are worse than river drakes in just about every way. Their AC being 2 points higher than that of a river drake is a small consolation. Zephyr hawks deal one damage die. Their only ability gives 2 attacks without a penalty increase and saves them an action if they also move.

River drakes:

  • Have better HP, perception, skills, ability scores, and attack rolls
  • Deal 2 damage dice
  • Have a 3-attacks-for-2-actions ability, unlimited use
  • Have a 2-moves-for-1-action ability, three times a day
  • Have a 10-foot burst AoE that deals significant acid damage both initially and persistently, along with a speed debuff, once every 1d6 rounds
  • Have a reaction that gives them a free strike and applies a penalty to the target’s roll if the strike hits

I don’t see how anyone could imagine zephyr hawks to be on the same level or be worth the same XP as river drakes.

Last night at the table, with a bit of skewed luck, a party that had just wiped the floor with two zephyr hawks lost three characters to two river drakes. They had full spells, abilities, and HP for the river drake fight, in contrast to having few remaining resources to fight the hawks the day before. Absolutely not surprising when you look at the blatant power difference between these two creatures.

What’s up with them both being level 3?