In terms of nesting sites, vultures prefer rocky cliffs, caves, grottos, and crevices. Visit Wikipedia and check their data on nesting places that included abandoned buildings, open fields, and old logs.
By midsummer the river can decline to a shallow but steady slow flow, indicating that a serious drought has affected the decreasing level of life-giving water borne from mountain brooks, going dry well before wildlife complete their life-cycles.
My first such encounter with a night-blooming cereus came about thanks to a gift from a friend, Alicia, who gave me this same cactus, likely Selenicereus grandiflorus (one of four known species), then only a few branching succulent stems, indeed leggy and sprawling in form.
Therein lurk in floral disguise their natural predators, the spiders. Many species garner bold arresting colors that in contrast may deter predators by announcing their yellow and black warning colors of hidden toxicity.