http://revach.net/article.php?id=4692

Section: Parshas HaShavua   Category: Quick Vort
Parshas Re'eh: Rav Chaim Kanievsky - Why The High Flying Shalach Took A Plunge
In Parshas Shmini (11:17-18) when listing the non-Kosher birds, the Shalach bird is listed 3 positions before the Racham.  In Parshas Re'eh (14:16-17) the Shalach slides down the list four places and is listed after the Racham.  Why?

Rav Chaim Kanievsky answers that the Gemara (Chulin 63a) says that when Rebbi Yochanan saw a Shalach he said the pasuk, "Mishpatecha Tihom Rabba; Your judgement is a deep abyss."  When he saw a Racham he said, "Rachamim came to the world."  The Shalach represents Din and the Racham represents mercy.

In a perfect world Din which is perfectly just, rules.  That is how Hashem wanted to create the world until He saw that world needed Rachmanus to survive.  Now the world is not perfectly just since mercy is mixed in.  LeAsid Lavo Din will reign supreme once again.
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Before the Chait of the Meraglim, Moshe was supposed to enter Eretz Yisrael and Moshiach would have come.  Until the Chait the world was set to march towards perfection and Din ruled.  Therefore, in Parshas Shemini, the Shalach which is Din, is listed before the Racham.  In Parshas Re'eh, as the Bnei Yisrael are set to conquer Eretz Yisroel without Moshe, and destined to go to Galus once again, Hashem shines his Rachamim on the world, and the Shalach is pushed down the list, letting the Racham come out on top.