These are Davis's Tree Crickets calling. They have a high pitched trill that sounds almost frog/toad -like. You can hear Common True Katydids and a Lesser Anglewing Katydid in the background, perhaps Fall Field Crickets.
Recorded on August 23, 2016 about 8:30pm with Fostex FR-2, Sennheiser ME62, and Telinga Parabola. Location: Channelized stream at head of west Dyke Marsh, at the footbridge (which puts me about 8 ft above the ground next alongside a Catalpa tree). Edited in Audacity. Fade in/out. High-pass filter.
recording file: B20h36m26s23aug2016y
Photo by Lisa Brown (creative commons, attribution, non-commercial; http://bit.ly/2b6RcCu).
Usually high in the treetops, this Common True Katydid (Pterophylla camellifolia) was calling on the ground!.Though they have large forewings they can not fly. The previous evening there had been a severe thunder storm and he may have been knocked out of the tree. However, not necessarily, they are known to walk on the ground during mating season to where others are calling. Whatever the circumstances, he provided a perfect opportunity for a close-up sound recording!
Recorded Aug 18, 2016 at about 11:20pm with a Fostex Fr-2, Sennheiser ME62, telinga parabola. Edited in Audacity: fade in/out, and high pass filter. Location: River Towers Picnic Grove, adjacent to west Dyke Marsh. 80 degrees F, partly cloudy.
(recording file: B23h23m24s18aug2016y.wav)
Photo by USGS BIML, Public Domain (http://bit.ly/2b43BLL).
Recorded August 18, 2016 at @ 11PM WITH FOSTEX FR-2, SENNHEISER ME62, TELINGA PARABOLA. Location: west Dyke Marsh (uppermost nw corner.) Edited in Audacity: Fade in/out, high pass filter, amplification.
recording file: B23h04m33s18aug2016y
This sound recording is a morning cicada, aka swamp cicada (Neotibicen tibicen tibicen)that is singing in an oak tree adjacent to west Dyke Marsh. There is background noise of cars and possibly the train--tooting-- in distance.
Recorded with Fostex FR-2, Sennheiser ME62, Telinga Parabola about 9:30am on August 20, 2016. Edited in Audacity: Fade in/out, absolutely no filters).
recording file: B09h34m31s20aug2016y
image taken 8/16/2014 by me. found low in vegetation along the Haul Rd in DYke Marsh. I think it is same species, but not sure.)
These cicadas were everywhere, the sheds decorated tree leaves like Christmas ornaments. Despite their prevalence, we didn't hear much in the way of calls during the evening.
Very small cicada, colored as shown. Very alert, hard to approach. Found in shortgrass prairie on sloping hillside with Gambel's Oak thickets and scattered, mixed conifers. About four specimens observed.
Medium-sized, all-black insect as shown. Found in parking lot of visitor center after dark. Surrounding habitat is shortgrass prairie on hillside with Gambel's Oak thickets, and scattered, mixed conifers.
Very large cicada, colored as shown. Attracted to lights at night. Habitat is shortgrass prairie on hillside with Gambel's Oak thickets and scattered, mixed conifers.
Small, delicate, resembles a lacewing more than a cricket. This is a male specimen, found inside a restroom building. Surrounding habitat is shortgrass prairie with Gambel's Oak thickets.
Medium-sized cicada, marked with orange as shown. Several specimens were observed in mixed conifer forest with Gambel's Oak in understory. Map location is approximate.
Observed singing from Liriodendron tulipifera, 11:30 am following morning rain. Photograph is of the same individual. Song of Neotibicen robinsonianus precedes that of N. tibicen.