TPWD's Aplomado Falcon Species Overview
(or copy/paste http://www.tpwd.state.tx.us/huntwild/wild/species/aplomfal )
The above link is a great way to get familiar with Aplomado Falcons as they currently exist in Texas.
Here is what they say about How You Can Help
(All added emphasis mine.)
Aplomados can be sensitive to human disturbance, especially during the breeding season. Human activity, including close or prolonged intrusion in a bird's territory, or loud and unusual noises, can cause nest abandonment. Human intrusions can also make Aplomados more susceptible to detection and harm from potential predators. A safe viewing distance is 200 yards or more. Suitable viewing at this or greater distance may require a spotting scope with 10 to 15 X or greater magnification. Birders should always respect private property rights in Texas regardless of the species being pursued.
Birders should keep in mind that Aplomados remain extremely rare in Texas and are federally- and statelisted as endangered. Therefore, all reasonable and suspected sightings of this bird should be reported immediately to an expert birder, Texas Parks and Wildlife Department, or the U.S. Fish and Wildlife Service for further verification. Observations should include a detailed description of the bird's location, appearance, activity, and surroundings. Verification of sightings is extremely important in the context of the Aplomado's scarcity and future conservation.
Ultimately, recovery of Aplomados in Texas will depend on the interest and direct involvement of private land owners since lands within the falcon's former range are mostly in private ownership. Texas land holders interested in promoting Aplomado Falcon conservation measures should consult with experts in the Texas Parks and Wildlife Department, U.S. Fish and Wildlife Service, or The Peregrine Fund for technical guidance and other assistance. Texans can contribute to nongame wildlife resources conservation by supporting the Texas Parks and Wildlife Department's "Special Nongame and Endangered Species Conservation Fund" and by purchases of special nongame decals and stamps issued by the department. A set portion of the revenues generated by these programs is used to purchase endangered species habitats and to support the publication of nongamewildlife informational materials and other nongame activities.
...another help is a good headwind.