This month will be devoted to song rate graphs – concentrating on the trilling species in the US: nigricornis, niveus and varicornis species groups and Neoxabea bipunctata. Each day will offer a graph of one species showing frequency by pulse rate of the male song. The remaining days will build a combined graph, and perhaps show some species from outside the US. I use RavenLite to determine frequency (I place the cursor at the center of the envelopes) and to count the pulse rate (I use only a 1 second snapshot – not an average).
I am using recordings from the Singing Insects of North America, iNaturalist, Macaulay Library, Orthoptera Species File and from my own library of recordings. Trendlines (linear) are included as an option offered through Microsoft Excel. These graphs should not be considered research grade, they are simply intended to give us a glimpse of how the species’ songs compare to each other.
I will also occasionally put expected temperatures on the top of each species’ graph, or on the trendlines. Some are actual temperatures, while others are filled in as estimates. In looking at spreadsheets in SINA and my own recordings, it is interesting how much variation there is in frequencies….even at the same pulse rates by the same recordists….there is still so much we do not know about these amazing insects.
NOV 30 – Logarithmic and Linear Trendlines of US Trillers
10 continuous trillers, 4 intermittent trillers, 3 intermittent bursts of trilling (Linear below; Logarithmic above)
NOV 29 – Nicaragua Oecanthus
NOV 28 – North American Neoxabea
N. ottei and N. cerrojesusensis were recorded in one area of Nicaragua, on two evenings of same temperatures, and no permit to import live individuals to the U.S. for further study.
NOV 27 – Asia and Australia
With limited access to recordings, and the fact that many of these species have chirping or chirp-like patterns to their songs, it is difficult to make any valuable comparisons, but I thought I would include it as a nice way to see the various species in India, China, Australia and other Asian countries.
NOV 26 – European Species
The recordings reflected in the graph above were all accessed from iNaturalist. I no longer try to ID to species any submissions outside of the Americas or the Caribbean. Even though there are some very clear pattern matches for these two species, there are also some recordings that could be either species based on pattern. There are some that look like continuous trilling (O. dulcisonans), some that are intermittent short bursts of trilling (O. pellucens), but there are also some with shorter trains of continuous trilling that could actually be O. pellucens, and some with longer bursts of intermittent trilling that could actually be O. dulcisonans – IMO. Below is a chart showing data included in this graph. Countries in bold font are O. dulcisonans…all others are O. pellucens (as identified on iNaturalist).
NOV 25 – Potentially New Species
Oecanthus californicus pictipennis has long been suspected to be a distinctly different species, even though it is currently listed as a subspecies of Oecanthus californicus. However, it has distinctly and consistent coloring, and is found on only certain types of conifers (Juniper and Pinyon Pine). As you can see above, both the pulse rate and frequency are different for these two ‘species’ at 75F. A DNA project should settle this question – with results expected in 2024.
A very dark ‘Pine’ tree cricket found in the Lyons, Colorado area on Ponderosa Pines matches the song rate by frequency trendline of Oecanthus pini found throughout most of the eastern US. However, the song rate by temperature is quite different between these two ‘species’. Specimens were also sent of this ‘species’ to the DNA project.
NOV 24 – Fast Trillers
In determining O. celerinictus vs O. forbesi, current range maps indicate having a recording of 45-50 pulses per second at a frequency of 3.4kHz the area that would be most difficult includes extreme: southern Illinois, western Kentucky, western Tennesse, northeast Arkansas and southeast Missouri.
NOV 23 – Five Slow Trillers in Western North America
These five species can be found in the far western states of the US, and in British Columbia and Alberta in Canada. There is a healthy population of Oecanthus salvii in Bristish Columbia, and Oecanthus beameri is thus far known only from the White Sands area in New Mexico, USA.
These species show how helpful knowing an accurate temperature of where the tree cricket was singing can be very useful in determining species. Imagine if you had a recording where the frequency was 3.4kHz and the pulses per second was 40 — just knowing those two measurements would not lead to a confident species identification.
NOV 22 – Six Slow Trillers in the Eastern US
The six species above can easily be confused with one another while searching for tree crickets in the eastern US – including north and east Texas. This graph shows how sometimes the temperature is an important factor in trying to determine species. However, even the temperature is sometimes not enough to make a good ID. Although occasionally Pine (O. pini) or Tamarack (O. laricis) can be found on surrounding vegetation, they are usually found on conifers. Therefore, knowing they are on a pine, spruce, yew, cedar, hemlock or tamarack is important.
In instances when the lines cross or are very close to each other, seeing the coloring and/or antennal markings are very helpful in determining species.
NOV 21 – Five Slow Trillers in the Western US
The five species above can easily be confused with one another while searching for tree crickets in the southwestern US – including Texas. This graph shows how sometimes the temperature is an important factor in trying to determine species.
NOV 20 – Nigricornis Species Group
You can see the challenges the nigricornis species group presents. If you have a trilling tree cricket singing 40 pulses per second at 3.5kHz, it would be impossible to ID to species using only a recording. Likewise, a male singing 50 pulses per second at 3.7kHz could be one of three different species. That is why appearance, location and an accurate temperature of the spot where the male was perched while singing are so important in trying to identify tree crickets to species.
In the next few days, I will make some species comparisons based mainly on general location.
NOV 19 – Oecanthus salvii (Sage tree cricket)
NOV 18 – Oecanthus beameri (White Sands tree cricket)
NOV 17 – Oecanthus laricis (Tamarack tree cricket)
Note: This species has a very limited number of recordings available to me, in a narrow range of temperatures.
NOV 16 – Oecanthus pini (Pine tree cricket)
NOV 15 – Oecanthus forbesi (Forbes’ tree cricket)
NOV 14 – Oecanthus celerinictus (Fast-calling tree cricket)
NOV 13 – Oecanthus argentinus (Prairie tree cricket)
NOV 12 – Oecanthus nigricornis (Black-horned tree cricket)
NOV 11 – Oecanthus quadripunctatus (Four-spotted tree cricket)
NOV 10 – Oecanthus walkeri (Walker’s tree cricket)
NOV 9 – Niveus species group and Neoxabea
NOV 8 – Oecanthus exclamationis (Davis’ tree cricket)
NOV 7 – Oecanthus niveus (Narrow-winged tree cricket)
NOV 6 – Neoxabea bipunctata (Two-spotted tree cricket)
NOV 5 – The Varicornis Species Group
This graph was created from the data of 44 recordings. There initially were 57 recordings included, but the most extreme outliers from each species were removed to create a graph that more clearly shows differences between the species. Texas tree cricket and Different-horned tree cricket are the most different – which is helpful to know since they can be mistaken for each other in photos. Song analysis for IDing becomes a problem when you have, for example, a recording with 35 pulses per second at 3.2 kHz. That falls midway between Texas and Western.
This graph below is the original graph – with several overlapping trendlines. Again, none of the graphs should be considered research grade.
NOV 4 – Oecanthus latipennis (Broad-winged tree cricket) – varicornis species group
NOV 3 – Oecanthus californicus (Western tree cricket) – varicornis species group
NOV 2 – Oecanthus texensis (Texas tree cricket) – varicornis species group
At higher temperatures, Texas tree cricket has the slowest song rate of the four varicornis species group members in the US.
NOV 1 – Oecanthus varicornis (Different-horned tree cricket) – varicornis species group
One of the fastest trillers in the US, a member of the varicornis species group.
