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The habitat of the endangered Blunt-nosed leopard lizard!
- 1. The habitat of the endangered Blunt-nosed leopard lizard is determined by an interplay between native shrub cover and invasive grass abundance. Alessandro Filazzola, Westphal M., Powers M., & Lortie. C.J.
- 3. Distributional records for blunt-nosed leopard lizard USFWS 1998 Ciervo-Panoche Natural Area Carrizo Plain National Monument
- 5. Role of shrubs for lizards Thermoregulation Protection from predators Territory landmark
- 6. Role of shrubs for lizards Reduce invasive grass Increase food availability Burrows Intermediary species
- 7. + - ??
- 8. Purpose: What is the role of native shrubs for the blunt- nosed leopard lizards? Hypothesis: Shrubs either directly provide a benefit to the leopard lizard and/or indirectly modify the landscape, such as altering grass cover.
- 10. Methods
- 11. Methods Shrubs - Dimensions - Volume - Canopy cover - Burrows - Trails - Scat Invasive grasses - Residual dry matter weight
- 12. Methods
- 13. Data analyses Ordinary kriging -> for interpretation of intermediary points Examining auto-correlation -> Moran’s I Statistical tests -> Logistic regression
- 14. Microscale results = 1.87; max = 7
- 15. Microscale results N.S. Length Height Volume Trails Burrows P < 0.001 Canopy RDM
- 16. Lowest RDM, highest scat
- 18. Implications for conservation Half of shrubs from 2013 also had scat in 2014 a) Lizard families from the previous year b) The “Perfect” shrub
- 19. What is the perfect shrub? Low invasive grass cover Low shrub density <5000 km-2 With burrows With a canopy >50 alive
- 20. Implications for conservation Lizards have short home ranges, 2-4 hectares (Warrick et al. 1998) = ~120 hectares
- 22. Implications for conservation Lizards have short home ranges, 2-4 hectares (Warrick et al. 1998) Manage for the “perfect” shrub
- 23. Thank you!! Dr. Michael Westphal Dr. Christopher Lortie Amanda Liczner Michael Powers BLM Hollister Field Office
Editor's Notes
- I would say that the blunt-nosed leopard lizards habitat is determined by an interplay of multiple factors, important, shrub cover and invasive grass abundance. The reason why I say interplay is because the interactions at times can be quite complicated.
- The focal species here is the endangered blunt-nosed leopard lizard. Because its habitat is in decline, there has been a large push to better understand the habitats they currently populate. The leopard lizard is carnivous, and so does not rely on plants for nutrition, yet vegetative composition strongly determines their habitat.
- The currently distribution of the BNLL is to these areas within the San Joaquin Valley. The question then becomes, what makes these habitats ideal for the leopard lizard.
- What we have currently then is this interplay between the dominant shrubs in the system, the invasive grasses and our BNLL. What we know for certain is that the shrub positively increases the invasive grasses and that these grasses have a detrimental impact on lizard. What we don’t know is the role the shrubs play on the leopard lizard. Is there an indirect effect of the shrubs increasing the grasses which hinders the leopard lizard, or is there more of a direct effect by the shrub on the leopard lizard. Is the effect positive or is it negative? It is determining these missing link in this interaction web that will significantly assist conservationists in managing the BNLL.
- The purpose of this project then was to resolve the effect of the shrubs on the leopard lizards. The shrubs are native and thus co-evolved with the BNLL, thus it is unlikely the shrubs are responsible for their population decline. Moreover, there has been preliminary evidence of lizards being frequently seen and captured under shrubs.
- You can see this from our pervious graph where in 2014 grass overall was significantly lower but the lizards remained relatively consistent.
- Half of shrubs from 2013 also had scat in 2014. I believe this could have two possible explanations. The first being that they are the returning lizard family from the previous year. These lizards species live for two or more years so it may be expected that they treat one as a consistent home for themselves. However, this assumes that the lizards associate with only one shrub, so this may not entirely be true. What I think to be more likely what is going on is the “perfect shrub” concept. These are shrubs that consistently have certain traits that we most likely see re-occurring scat even decades into the future.
- When I first joined this project I was tasked with finding what the perfect shrub was. What are the characteristics of shrubs that are perfect for lizards so we know which ones to preserve or which ones could sustain lizards in other habitats. What I’ve realized after two years is that there is no true perfect shrub, but instead a set of conditions at the landscape level that best suit the lizards. In this case, the perfect shrub is one that is located in an area of low annual grass, medium to low shrub density. With burrows although the number of burrows does not appear to matter and lastly a canopy greater than 50% alive
- Lizards have short home ranges and our study area was around 120 hectares in size. This means that the lizards found within the defined groups here are unlikely to be moving around beyond these areas easily. If we were to clear the entire plateau of grass, it may take a while for the lizard population to expand beyond their current areas.
- Lizards have short home ranges and our study area was around 120 hectares in size. This means that the lizards found within the defined groups here are unlikely to be moving around beyond these areas easily. If we were to clear the entire plateau of grass, it may take a while for the lizard population to expand beyond their current areas.