1. An unmanned aerial vehicle (UAV) for delivering a parcel, the UAV comprising: a UAV chassis comprising: an upper portion including a plurality of propulsion members configured to provide lift to the UAV chassis; a lower portion coupled to the upper portion, the lower portion defining an internal cavity; one or more landing gear coupled to the UAV chassis between the upper portion and the lower portion; and a parcel carrier configured to be selectively coupled to and decoupled from the UAV chassis independently of the one or more landing gear, the parcel carrier comprising: an engagement housing configured to be at least partially inserted within the internal cavity of the lower portion of the UAV chassis and thereby secured to the UAV chassis; and a parcel carrying mechanism coupled to and positioned below the engagement housing, wherein the parcel carrying mechanism is configured for engaging and holding the parcel.