Stressors/Threats

Relevance to Species

HABITAT LOSS

breeding

Loss of habitat to agricultural and urban development is regarded as most serious historic threat to the species. Loss continues today, to a lesser degree, as urban development occurs in previously undeveloped land that may still support this species.

dispersal

Dispersal is limited for a small snake. The ability to disperse has been compromised by roads, developed areas, irrigation and drainage ditches, and areas with impacted soils.

foraging

size of foraging area is unknown, may be related to available food supply and available suitable soils; diversity of resources is important

plant locations

N/A

wintering

not applicable

migratory stops

not applicable

diurnal preferences - day, temporary

uses rodent burrows and litter (e.g., boards) as shelter for unknown periods of time; rodents have largely been eradicated as a result of agricultural and urban development from areas where this snake once lived

diurnal preferences - day, long-term

rodent burrows and litter

diurnal preferences - night

rodent burrows and litter

fire threat

may be a threat if it results in loss or conversion of vegetation; direct effects of fire on snake are unknown, probably lethal under some circumstances, not under others

HABITAT ALTERATION

prey

consumes diverse invertebrate prey; loss or reduction of populations of suitable prey species through habitat loss and invasive competitors is probably a significant threat, but needs further research

nest sites

rodent burrows and litter

vegetation composition/density

loss of native floodplain vegetation by conversion to agricultural fields was important cause of population loss

habitat conversion

loss of native floodplain vegetation by conversion to agricultural fields was important cause of population loss

HABITAT ALTERATION continued

fragmentation

fragmentation of historic habitat may have led or contributed to endangerment of this species; remaining potentially suitable areas are isolated by various barriers

invasive plant species

invasion by mesquite, bufflegrass, and red brome reduces vegetation diversity and can lead to fires, changes in soil characteristics, and prey availability

invasive animal species

effects are unknown, but concern has been expressed about invasive non-native insects such as cockroaches out-competing native food animals

habitat rehabilitation potential

questionable: anything that restores native vegetation is probably good; habitat rehabilitation to enhance connectivity may improve long-term survival if the species is present or reintroduced

contaminants

unknown

nutrient enrichment

probably irrelevant

water accessibility

probably irrelevant

drought

may result in reduction of prey populations

flood

may result in loss of individuals and/or areas that were formerly inhabited; much of this species' natural habitat gets flooded occasionally, and under natural conditions snakes survive, but flood regime has been altered by human activities so that floodplains in part of the historic range may remain under water for longer periods than before alteration and effect on snakes is unknown

groundwater depletion

may have led to loss of suitable habitat in the past, and may impede restoration of suitable habitat

root zone water loss

may have led to loss of suitable habitat in the past, and may impede restoration of suitable habitat

artificial water sources

probably irrelevant

infiltration

probably irrelevant

runoff

probably irrelevant

edge effects

unknown, but may contribute to isolation and predation on snake

HABITAT ALTERATION continued

fire threat

may be a threat if it results in loss or conversion of vegetation; direct effects of fire on snake unknown, probably lethal under some circumstances, not under others

water quality - turbidity

probably irrelevant

water quality - salinity

probably irrelevant; but may result in changes in soils and invertebrate community

water quality - conductivity

probably irrelevant

water quality - dissolved oxygen

probably irrelevant

water quality - effluent

probably irrelevant

sheetflow disruption

probably irrelevant; but may result in changes in soils and invertebrate community

flow rate

probably irrelevant

land use history

historic agricultural use may render land unsuitable for this species; long-term effects are unknown

roads - dust

probably irrelevant

roads - erosion

probably irrelevant

roads - surface water diversion/ponding

may have adverse impacts on prey availability very locally

roads - asphalt/contaminants

unknown

SPECIES CHARACTERISTICS

dispersal mechanism

moves overland, apparently preferring certain types of soil; dispersal may be impacted adversely by roads, ditches, and unsuitable areas

behavior traits

unknown

habitat rehabilitation potential

unknown-- habitat may have been altered in ways we do not understand that are important; goal is to restore fully functioning floodplain ecosystem to historically suitable habitat, but potential for success is unknown

colonization potential

unknown but probably very limited due to multiple barriers

effective population size

unknown

total population size

unknown

SPECIES CHARACTERISTICS continued

fecundity

not considered a problem, although long-term survival may be a problem

knowledge/data on species

essentially nothing is known about demographics or population dynamics; specific habitat requirements are not known, other than undisturbed floodplain community

seasonal specialization

unknown, prey animals are clearly seasonal in abundance and life cycle, so snake must have the ability to switch prey or fast and gorge

captive breeding/translocation potential

unknown, but may be a useful approach

genetic isolation

may be a problem

inbreeding

may be a problem

diurnal specialization

not considered to be a problem

off-site mortality - migratory

no information is available

off-site mortality - from surrounding land uses

no information is available

breadth of resource use

appears to have specialization to a narrow range of resources, but this is not well understood yet

sensitivity to disturbance

unknown

adaptability

fairly limited in habitat selection to specific soil types

charisma

not very charismatic, except to a few people

INTERSPECIFIC FACTORS

predation

unknown

disease

unknown

pollinators/seed dispersers

not applicable

competition

unknown

brood parasitism

not applicable

domestic/feral animals

not likely to be a problem

invasive species

effects unknown, invasive plants alter habitat adversely; invasive insects may alter prey base

ANTHROPOGENIC FACTORS

edge effect

unknown

disease

unknown

fire threat

may be a threat if it results in loss or conversion of vegetation; direct effects of fire on snake are unknown, probably lethal under some circumstances, not under others

off-road vehicles - dust

not considered a problem

off-road vehicles - erosion

not considered a problem

off-road vehicles - noise

direct impacts to snakes, and impacts to soils may be adverse

mining

not considered a problem

passive recreation

not considered a problem

grazing - vegetation impacts

may be harmful if it reduces vegetation diversity

grazing - soil impacts

may be harmful if it compacts soil

collection/hunting

historically may have been a problem in that snakes in the area have been collected; no longer considered a problem because snakes have not recently been found in area

herbicides

unknown, may effect prey base and vegetation upon which it depends

insecticides

not thought to be a problem, except as they may affect prey base

pesticides - impacts to species

not considered a problem

pesticides - impacts to prey

may be a problem, but effects are unknown

direct take/mortality

not considered a problem

noise

not considered a problem

light

not considered a problem

movement

not considered a problem

landscaping

not considered a problem

invasives

may be a problem

ANTHROPOGENIC FACTORS continued

domestic/feral animals

unknown

dumping

not considered a problem, may actually be beneficial by providing cover

undocumented immigrants

not considered a problem, may actually be beneficial by providing cover in the form of litter

increased road density

results in loss of habitat, barriers to dispersal, and direct mortality

road kill

serious problem, at least historically

electrocution on powerlines/towers

not applicable

CONNECTIVITY

fragmentation

this is probably a significant problem because the only remaining habitat is isolated

barriers

roads, ditches, agricultural fields, urban development, unsuitable habitat

traffic volumes

may be problematic by increasing roadkill risk

wash incision

unknown

corridor width

unknown

habitat patchiness

connectivity is considered crucial

riparian/upland connection

unknown

road crossings

may be hazardous

road width

unknown, presumably wider roads are worse than narrower roads

vegetation next to roads

probably irrelevant

Stressors/Threats

Relevance to Species

HABITAT LOSS

foraging

size of foraging area is unknown, but will forage over large distances; thought to prefer "edges" of habitat

wintering

winter roosts are generally caves or mines, threatened by closure

migratory stops

roosts are necessary for migrants

diurnal preferences - day, temporary

unknown and unlikely

diurnal preferences - day, long-term

caves and mines are extremely important

diurnal preferences - night

needed, includes bridges, buildings, drainage culverts?, and other unknown

fire threat

probably minor

HABITAT ALTERATION

prey

moths, 3-10 mm, Noctuidae; but includes other insects; loss of prey= loss of bats

nest sites

maternity roosts critically important

vegetation composition/density

important as source of prey; protect riparian and other edges

fragmentation

potentially does not matter, it lives in a fragmented landscape

invasive plant species

unknown, probably affects prey base

habitat rehabilitaion potential

limited for roosts; conditions needed are generally unknown; gating roosts could be beneficial

contaminents

unknown; there is some indication that bats can acquire toxic materials in roosts, and considerable evidence that some species can acquire toxic doses of insecticides by consuming contaminated prey

water accessibility

drinks from and forages over water; very small water sources are used, large water bodies have not been surveyed; could benefit by vegetation around water

artifical water sources

drinks from and forages over water; very small water sources are used, large water bodies have not been surveyed; could benefit by vegetation around water

edge effects

prefers foraging along edges

fire threat

may affect prey

water quality - turbidity

broadly tolerant of water quality

flow rate

may prefer still or slow moving water

roads - surface water diversion/ponding

may be beneficial

SPECIES CHARACTERISTICS

behavior traits

sensitive to disturbance at roosts

habitat rehabiitation potential

potential to increase prey base; could benefit by gating mines and caves; experiment with creating habitat?

fecundity

1 young per year, fecundity is low as with most bats

captive breeding/translocation potential

no success with moving from roosts

inbreeding

very low variability suggests inbreeding or small gene pool

off-site mortality - from surrounding land uses

could be driven from areas by renewed mining, urban expansion, human disturbance

sensitivity to disturbance

highly sensitive; outreach to recreational cavers and mine explorers is needed

adaptibility

not very adaptable to some changes, especially loss of roosts

charisma

mixed bag: bats have had a major change in public image in past two decades but some people still fear or hate; need to empasize that they eat pest insects

INTERSPECIFIC FACTORS

predation

limited knowledge; may be subject to predation by cats but this is not likely

disease

rabies may affect; others unknown

competition

unknown; has been found in roosts with other species

domestic/feral animals

may be preyed on by cats, but this is not likely

ANTHROPOGENIC FACTORS

edge effect

edges are prefered foraging sites

off-road vehicles - dust

ORVs may be a problem because they get people to roost sites and result in disturbance

mining

renewed mining in areas with old mines may result in disturbance or loss of roosts

passive recreation

disturbance of roosts; should route trails to avoid roosts

grazing - vegetation impacts

may affect prey base

collection/hunting

not thought to be a problem

herbicides

not thought to be a problem, except as they may affect prey base

insecticides

impacts have been reduced over time, but still may be a problem

pesticides - impacts to species

impacts have been reduced over time, but still may be a problem

pesticides - impacts to prey

this could be significant

direct take/mortality

little effect except from mine hazard abatement practices, which could be serious impacts; road paving and de-icing may affect

light

bright lights near roosts may affect

landscaping

native plants could provide beneficial opportunities for habitat improvement

dumping

may affect if in roost sites

undocumented immigrants

may affect when they use caves and mines for shelter or dumping grounds

increased road density

may be a problem, low-flying bats could get hit by cars while foraging along road edges

road kill

may be a problem, low-flying bats could get hit by cars while foraging along road edges

CONNECTIVITY

barriers

large cities with abundant lights could be barriers

traffic volumes

increased volume could lead to increased road kill

wash incision

could create roost sites but could also take some away

corridor width

buffers along washes would be good but width unknown

habitat patchiness

depend on what is around them; patchiness could be good because it could increase insect diversity

riparian/upland connection

bridges could be improved as bat roosts

road crossings

could be opportunity for foraging or hazard due to roadkill

vegetation next to roads

could be opportunity or hazard; recommend not planting edges along larger and faster roads, allow space between trees and roads