Howell’s triteleia (Triteleia howellii) COSEWIC assessment and status report: chapter 12

Range of Occurrence in Canada:

British Columbia

extent of occurrence (EO) (km²):

50

specify trend (decline, stable, increasing, unknown):

uncertain

are there extreme fluctuations in EO (> 1 order of magnitude)?

no

area of occupancy (AO) (ha):

3-4

specify trend (decline, stable, increasing, unknown):

decline (loss of 3 sites)

are there extreme fluctuations in AO (> 1 order magnitude)?

no

number of extant locations:

9

specify trend in # locations (decline, stable, increasing, unknown):

decline

are there extreme fluctuations in # locations (>1 order of magnitude)?

no

habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat:

declining

generation time (average age of parents in the population)(indicate years, months, days, etc.)

?

number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values):

704

total population trend:  specify declining, stable, increasing or unknown trend in number of mature individuals:

Apparently stable from short-term observations at a few of the locations

if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)

are there extreme fluctuations in number of mature individuals (> 1 order of magnitude)?

no

is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise)populations between which there is little exchange, i.e., < 1 successful migrant / year)?

uncertain

list each population and the number of mature individuals in each:

1. Albert Head-8,
2. Witty’s Lagoon Regional Park-43
3. Horth Hill Regional Park-4
4. Gordon Head, Margaret Bay-51
5. Somenos Lake-45
6. Cowichan River Estuary-62
7. Cowichan Garry Oaks Preserve-450
8. Beacon Hill Park-40
9. Thetis Lake Regional Park-1

specify trend in number of populations (decline, stable, increasing, unknown):

Apparently stable

are there extreme fluctuations in number of populations (>1 order of magnitude)?

no

Rescue Effect (immigration from an outside source)

Low

does species exist elsewhere (in Canada or outside)?

yes

status of the outside population(s)?

Critically imperiled in California, unknown status in Washington and Oregon

is immigration known or possible?

unknown

would immigrants be adapted to survive here?

unknown

is there sufficient habitat for immigrants here?

Perhaps but unlikely