Kansas: lesser prairie chickens found outside current known range

Computer modeling system reveals previously unknown
breeding grounds

PRATT – The Kansas Department of Wildlife,
Parks and Tourism (KDWPT) recently used Maximum Entropy (MaxEnt)
modeling software to target searches for lesser prairie chicken
leks (breeding grounds) outside their current range in northwest
Kansas. MaxEnt modeling can identify areas with a high probability
of lek occurrence by analyzing presence-only data (not absence
data), making it an ideal method for analyzing lek survey data.

“We used MaxEnt to identify areas that had a relatively high
probability of occurrence outside the lesser’s known range and
targeted those areas to survey,” says Jim Pitman, small game
coordinator for KDWPT. “Finding chickens outside the known range
allows us to more accurately delineate the range and better target
conservation programs to ensure they are being implemented in areas
where chickens have the best chance to benefit.”

The targeted surveys were successful in locating new lek sites
and resulted in KDWPT extending the historic lesser prairie chicken
range 30 miles north. Despite high winds making it difficult to
detect leks, the biologists found both lesser and greater prairie
chickens and greater/lesser prairie chicken hybrids, called
“guessers,” present on 11 leks well outside the current known range
of the species. They also located 23 leks occupied solely by
greater prairie chickens and three leks in which species
composition could not be identified.

To determine the probability of lek occurrence, the MaxEnt model
compares a given set of landscape characteristics at known lek
sites to areas where lek occurrence is unknown. The landscape
characteristics include features that could influence lek site
selection by the lesser prairie chicken, such as vegetation type,
anthropogenic features, and elevation. The results showed that both
biological type – such as vegetation – and anthropogenic features –
such as highways – were important in predicting where leks
occur.

To identify areas for new lek surveys, the MaxEnt results were
filtered to include only areas with a high probability of lek
occurrence that overlapped native grassland or CRP in Ellis, Trego,
Graham, Sheridan, Rawlins, and Thomas counties. These
high-probability areas were then connected creating 15- to 20-mile
routes that biologists could search.

Historically, the lesser prairie chicken was found throughout
western Kansas, but over time its range receded due to habitat loss
and degradation. The federal Conservation Reserve Program is given
much credit for the species’ apparent stability in western Kansas,
and the new software model is helping identify the extent of that
stability, or perhaps even growth.

“MaxEnt is working really well, and we feel comfortable that
this model is doing a good job of predicting where lessers occur,”
Pitman explains. “Since we don’t have the manpower to survey every
square inch of potential range, MaxEnt will be very useful for
targeting our surveys, and most importantly, conservation programs
in the future.”

Because of the success of the KDWPT MaxEnt model, the Western
Governors Association (WGA) is supporting state wildlife agencies
from Kansas, Oklahoma, Texas, New Mexico, and Colorado in
developing a range-wide lesser prairie chicken support system that
incorporates MaxEnt modeling results, along with other
products.

 

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