and testosterone can be attributed to the increased need for aggressive behaviors. The first need for aggressive behavior comes from the drive to establish territory. This typically occurs within the first few weeks of mating season. The second need for aggression occurs after the first clutch of eggs have been laid. The male not only needs to guard the eggs, but also to guard his sexually receptive mate from other potential suitors. Thus, the male adopts an “alpha male status” when acquiring territory as well as during the egg laying period. This alpha male status, as mentioned before, comes from the significant increase of testosterone that occurs during the mating season. Further evidence of LH and testosterone mitigating aggression in bird species comes from studies on bird species such as the song sparrow and the European blackbird who build highly accessible refuges, known as open cup nests. Because open cup nests can essentially be built anywhere, there is little competition when it comes to nest building sites. Accordingly, both the song sparrow and the European blackbird do not show an increase in luteinizing hormone or testosterone during territory acquisition . However, not all species of birds show increased levels of testosterone and LH during aggressive behavior. In a landmark study, it was found that male western screech owls, when exposed to another male during the non-mating season showed aggressive behavior without the increase in LH and testosterone. However, when the owls were put in a situation that warranted aggressive behavior during the mating season, there was a large spike in LH and testosterone during the aggressive act. This suggests that the mechanisms of aggressive behavior during the mating and non-mating seasons are independent of each other or perhaps the increase in testosterone somehow increases the aggressive response during the mating season . Estradiol (E2), a type of non gonadal estrogen, seems to play a key role in regulating aggressive behavior during the non-mating season in several species of birds. As previously noted, many bird species during the non-mating season have low testosterone levels yet still manage to display aggression. As a primary example, when the Washington State song sparrow, a bird which shows fairly high levels of aggression during non-mating season despite low testosterone, is exposed to fadrozole, an aromatase inhibitor, the levels of aggression are greatly decreased. When the E2 was replaced, the aggressive behaviors reestablished themselves thus confirming