What is the gender method employed by Butler?

In Butler's opinion gender is a human construct. She observes animal and plant life, noting the multiple ambiguities where gender and sexuality and reproduction become fluid throughout a species. She views the ability of plants to reproduce asexually and the various methods of animals to engage in parenting as evidence for the malleability of those gender roles. Additionally, she focuses on animal species which do not participate in hierarchies, despite the fact that all animals exist within the ultimate hierarchy of the food chain. Through comparisons to the natural world Butler concludes that humans have constructed the concept of gender and forgotten along the way.