The New Mexico Rare Arthropod Resource

This species is found in ravines, dry or rocky washes, and rocky canyons as well as in hilly open woodlands and prairie gulches (Scott 1986, Opler and Wright 1999, Lotts and Naberhaus 2021, Cary and Toliver 2023). The Texas Roadside-Skipper generally lives in lowlands at elevations between 3500 and 6000 feet (1067-1829 meters) (Opler and Wright 1999, Cary and Toliver 2023, NatureServe 2023). This species is also generally found associated with limestone soil and rocky areas (Opler and Wright 1999, Lotts and Naberhaus 2021, NatureServe 2023). For the most part little is known about this species life history however, Brock and Kaufmann (2003) confirmed that Bulb Panicgrass (Panicum bulbosum ) is a larval host for the species and it is currently the only known one  (Brock and Kaufmann 2003, Bock et al. 2007, Lotts and Naberhaus 2021, Bailowitz and Brock 2022, Cary and Toliver 2023, NatureServe 2023). However, the species likely also uses several other native grasses  (Bock et al. 2007, Bailowitz and Brock 2022, NatureServe 2023). The Texas Roadside-Skipper has one brood in Arizona occurring from July to September (Opler and Wright 1999, Lotts and Naberhaus 2021, Bailowitz and Brock 2022). However, the species has two broods ranging from from April to August or September in New Mexico and west Texas (Opler and Wright 1999, Lotts and Naberhaus 2021, Bailowitz and Brock 2022, NatureServe 2023). During flight adults feed on nectar and can often be seen puddling on moist soil (Lotts and Naberhaus 2021, Cary and Toliver 2023). Males establish territories during flight often at the bottoms of gullies or other flyways which they defend from perches on large rocks (Cary and Toliver 2023).

This species has a small disjunct range in the lowlands of Texas, southern New Mexico, and southeastern Arizona. The species is also possibly in Mexico although experts disagree on this (Freeman 1973, Opler and Wright 1999, Brock and Kaufman 2003, Lotts and Naberhaus 2021)

This species underwent a NatureServe conservation assessment in 2020 and was ranked as globally vulnerable to extinction (NatureServe 2023). This determination was made from the species rarity in Arizona, its small range, and the number of widespread threats it is experiencing (NatureServe 2023). Currently no specific conservation actions are being taken for this species however, actions should be taken to protect habitat where this species occurs especially considering its vulnerability to development (Bock et al. 2007). Managing invasive species and promoting healthy fire regimes in areas where this species may also be beneficial.

Threats to this species are not well understood, though habitat loss and degradation due to development, overgrazing, invasive species, changes in fire regime, and climate change are likley threats. Development is a localized threat, as the species is not known to persist in areas once they are developed (Bock et al. 2007, NatureServe 2023). This species is also thought to be a specialist on grasslands and its only known host plant is a native grass species; native grass species are currently under threat across the southwestern United States due to overgrazing, invasive species, change in fire frequency and intensity, and changes in land use (Noss et al. 1995, Gori and Enquist 2003, NatureServe 2023). In fact, grasslands and shrublands in the American southwest are now critically endangered ecosystems, having declined by more than 98% (Noss et al. 1995). In addition, many butterfly species have been experiencing substantial declines likley due to warmer temperatures and drought as well as land use changes (Forister et al. 2021, 2023). The southwest is expected to get hotter and drier as climate change progresses, which is expected to adversely impact the native grass species that the Texas Roadside-Skipper relies on (Fletcher and Robbie 2004, Cook et al. 2009, Cook et al. 2015, Ludwig et al. 2017, Williams et al. 2022). These native grasses are at increased risk as invasive species decrease diversity across the region, creating habitats that are less drought tolerant (Ludwig et al. 2017).

This species also has several life history factors which put it at significantly increased risk for extinction. Firstly, this species is a dietary specialist as a larval with currently only one known host plant, Bulb Panicgrass (Bock et al. 2007, Lotts and Naberhaus 2021). Host specialization is a key indicator of extinction risk for the butterflies as threats to the hosts can quickly affect the butterfly population (Kotiaho et al. 2005, Palash et al. 2022, Forister et al. 2023). Secondly, this species has low mobility which is widely considered another key indicator of extinction risk in butterflies (Bock et al. 2007, Forister et al. 2023). Lastly, the species is univoltine across parts of its range, which is another key indicator for extinction risk in butterfly species (Forister et al. 2023, NatureServe 2023). These factors also put the species at risk for phenological mismatch, as having a limited number of host plants and a single brood requires the species to synchronize its emergence with its host plant and reduces opportunities for bet hedging (Patterson et al. 2019, USFS 2023).

The population size and trend are not known for this species. Determination of population size and monitoring of population trends is necessary to ensure the population is stable. Especially as several widespread, relatively common species of butterfly are in decline across the American west (Forister et al. 2021).

The species is reportedly rare or uncommon in the eastern portion of its range and it may require more attention there (Glassberg 2001). The species is also considered quite scarce in Arizona, which is on the western edge of the species distribution, so in all likelihood this species may just be rare or uncommon across its range (Bailowitz and Brock 1991, NatureServe 2023).

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