In the Talmudic Tractate Chullin (61b), our sages identify various simanim (signs or indicators), of kosher birds, through contrasting the attributes of two species, one kosher and the other non-kosher.
The תור, or turtledove, has four specific signs that render it as kosher, while the נשר, similar to an eagle [1], lacks all four of those signs and is therefore not-kosher. Without getting into all of the particulars, there is one siman that is tremendously fascinating. A bird that is a predator may not be eaten. In fact, being a bird of prey is a sufficient condition to render it non-kosher, even if lacks the three other non-kosher signs.
The Talmud (Gemara) in Chullin (59a) asks the obvious question: Why, then, are the other three simanim necessary? The Gemara answers that it could take an extended period of time to analyse the behavior of each bird and identify its predatory nature. The Torah, therefore, gave us three distinctively apparent signs, whose presence or absence are much easier to discover.
One bird of prey is particularly distinct from the others. The Torah uses a total of four names to describe a single creature, the vulture. The gemara in Chullin explains that there are over 100 different types of vulture. It seems a little peculiar for the Torah to list four varieties of this creature. Therefore, Rashi, in Parshat Re'eh, explains that the reason for all of the names is to properly ensure that no one will err and mistake one variety of this non-kosher bird for a kosher one. [2]
One such term, ראה (Deuteronomy, 14:13), literally meaning "sees", distinctly describes the vulture as a bird of prey. The Gemara in Chullin (63:) explains that this name corresponds to its tremendous vision which enables it to spot food from miles away; it can even spot a carcass in Eretz Yisrael from Bavel (Israel from Babylon, ed.).
This last statement seems a bit odd. Granted, the vulture has remarkable eyesight, however, the distance between Israel and Bavel is many hundreds of miles! Perhaps the Gemara is coming to teach us a particular character trait. A vulture is by nature a scavenger, constantly on the lookout for a carcass to consume. Its inherent nature is to seek that which is dead. It is therefore not hard for us to imagine why this is a negative character trait that should not be imbued within us.
The Mishna in Avot states,"רבי יהושע אומר עין הרע...מוציאין את האדם מן העולם": An individual who constantly takes a critical approach and continuously seeks out negativity within others risks forfeiting his place in the world. Apparently, that is the essence of the vulture. It does not seek something that is beautiful and lively; rather it focuses on that which is dead and decaying.
The food that we consume can have a profound impact on our essence. Rabbi Samson Raphael Hirsch states in Chorev (chapter 68) that one who eats carnivorous creatures is potentially influenced by their cruel nature. Therefore, as Torah observant Jews, we must take particular care as to what enters into our bodies. Perhaps it would be prudent to remember the popular adage, "You are what you eat."
[1]The identity of the נשר is not truly known. תוס' (Chullin 63a) specifically states that it is most definitely not the eagle.
[2] For more information, see Birds of the Torah זה הדבר by Rabbi Pinchus Presworsky