Strigiformes
Great Horned Owl (Bubo virginianus)
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type |
|---|---|---|---|---|---|---|---|
| Dietary Composition | Dipodomys ordii (0.11%), Microtus montanus (0.12%), Perognathus parvus (0.03%), Peromyscus maniculatus (0.63%), Thomomys umbrinus (0.10%) | relative proportion of prey species in the diet, based on pellet analysis | Male | Adult | 1 owl | Gund Research Ranch, University of Nevada | Exposure Factor Datasets |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type | Condition | Countries |
|---|---|---|---|---|---|---|---|---|---|
| Dietary Composition | mammals (47.0%), birds (5.2%), reptiles (15.7%), arachnids (8.7%), centipedes (7.0%), insects (16.5%) | percent of total numbers of prey items in diet, based on pellet analysis | Both Male and Female | Adult | 2 owls (49 pellets) | El Comitan, Baja California Sur | Exposure Factor Datasets | nesting | MEXICO |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type | Lab |
|---|---|---|---|---|---|---|---|---|---|
| Food Ingestion Rate | 62.6 | average daily consumption on an all mouse diet | g/d | Not Reported | Adult | 1 owl | collected in Larimer County, CO | Exposure Factor Datasets | Laboratory |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type | California Counties |
|---|---|---|---|---|---|---|---|---|
| Dietary Composition | Sylvilagus spp. (1.0%), unident. lagomorphs (0.2%), Peromyscus maniculatus (42.%), Microtus monatus (23.7%), unident. rodents (2.9%), Myotis spp. (1.9%), unident. mammal (1.5%), Podiceps nigricollis (1.0%), unident. rail (0.2%), Larus californicus (1.7%), unident. owl (0.4%), unident. blackbird (0.4%), unident. large bird (4.6%), unident. medium bird (1.2%), unident. small bird (6.9%), unident. vertebrate (1.0%), insects (8.3%), scorpions (0.4%) | percent occurence of prey items in pellets | Not Reported | Not Reported | 219 pellets, 518 remains | Paoha Island, Mono Lake | Exposure Factor Datasets | Mono |
| Dietary Composition | Lepus californicus (0.2%), Sylvilagus spp. (6.0%), unident. lagomorphs (1.7%), Peromyscus maniculatus (69.2%), Microtus monatus (0.7%), Dipodomys spp. (0.6%), unident. rodents (0.4%), Myotis spp. (1.1%), unident. chiropteran (0.2%), unident. mammal (3.9%), Larus californicus (1.3%), unident. large bird (7.1%), unident. medium bird (1.1%), unident. small bird (0.9%), unident. vertebrate (4.3%), insects (1.5%) | percent occurence of prey items in pellets | Not Reported | Not Reported | 188 pellets, 536 remains | Negit Island, Mono Lake | Exposure Factor Datasets | Mono |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type | California Counties |
|---|---|---|---|---|---|---|---|---|
| Dietary Composition | Microtus (66.7%), Peromyscus (27.6%), Dipodomys (1.1%), Sylvilagus (0.3%), Euphagus cyanocephalus (0.3%), Sorex (0.2%), Tadarida brasiliensis (0.2%), Mustela frenata (0.2%), unident. bird (1.4%), unident. small mammal (0.7%), insect (1.3%) | percent occurence of prey items in pellets | Not Reported | Not Reported | 107 pellets | Tule Lake National Wildlife Refuge | Exposure Factor Datasets | Siskiyou |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type |
|---|---|---|---|---|---|---|---|
| Dietary Composition | Sylvilagus nuttallii (12.4%), Spermophilus washingtoni (0.4%), Thomomys talpoides (29.7%), Perognathus parvus (12.5%), Dipodomys ordii (1.4%), Reithrodontomys megalotis (0.3%), Peromyscus maniculatus (6.2%), Neotoma cinerea (2.1%), Microtus montanus (7.7%), Mus musculus (0.2%), unident. microtinae (4.5%), Mustela frenata (0.4%), Anas platyrynchos (2.6%), Phasianus colchicus (2.5%), Fulica americana (1.5%), Charadrius vociferus (0.2%), Tyto alba (10.7%), Sternella neglecta (0.2%), unident. Fringillidae (0.2%), unident. Passeriformes (1.2%), unident. snake (1.4%), Cyprinus carpio (1.3%), Stenopelmatus spp (0.2%) | percent of total prey biomass | Not Reported | Not Reported | 234 pellets | Esquatzel Coulee, Franklin County | Exposure Factor Datasets |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type |
|---|---|---|---|---|---|---|---|
| Dietary Composition | unident. snake (0.3%), Sylvilagus nuttallii (19.2%), Lepus californicus (14.3%), unident. leporid (16.1%), Spermophilus townsendii (0.6%), Thomomys townsendii (14.6%), Perognathus parvus (0.4%), Dipodomys ordii (11.1%), Reithrodontomys megalotis (0.2%), Peromyscus spp (2.3%), Neotoma cinerea (4.6%), Neotoma lepida (2.0%), unident. woodrat (0.3%), Microtus montanus (4.7%), Mus musculus (0.7%), Mustela frenata (0.1%), Falco sparverius (0.1%), Phasianus colchicus (1.9%), Callipepla californicus (0.1%), unident. galliform (0.4%), Fulica americana (0.4%), Columba livia (0.9%), Tyto alba (0.3%), Sturnus vulgaris (0.2%), unident. passerine (0.6%), unident. bid (3.4%) | occurence in diet as percent of total prey biomass, based on pellet analysis | Not Reported | Not Reported | 14 nesting areas, 1472 prey items | Snake River Birds of Prey National Conservation Area (42 deg, 50'N, 115 deg, 50'W) | Exposure Factor Datasets |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type | Lab |
|---|---|---|---|---|---|---|---|---|
| Growth Rate | see figures | figures showing weight increase and feather growth for 0-73 days of age | Not Reported | Nestling | five owls | collected in California | Exposure Factor Datasets | Laboratory |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type |
|---|---|---|---|---|---|---|---|
| Growth Rate | 0.1900 | growth constant based on logistic growth equation | Female | Nestling | 1 owl | Delaware County | Exposure Factor Datasets |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type | Condition |
|---|---|---|---|---|---|---|---|---|---|
| Time of Mating/ Laying | February (peak), March (end) | egg laying dates | Female | Adult | 16 nests | Pima and Pinal Counties | Exposure Factor Datasets | breeding | |
| Clutch or Litter Size | 2.5 | mean clutch size | eggs/clutch | Female | Adult | 16 nests | Pima and Pinal Counties | Exposure Factor Datasets | breeding |
| Fledging or Weaning Rate | 1.1 | rate of production of young at least 4 weeks old | young/nest | Not Reported | Nestling | 16 nests | Pima and Pinal Counties | Exposure Factor Datasets | breeding |
| Fledging or Weaning Rate | 9/16 | fraction of nests that sucessfully raised at least one nestling to the age of 4 weeks | successful nests/total nests | Both Male and Female | Adult | 16 nests | Pima and Pinal Counties | Exposure Factor Datasets | breeding |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type | Error |
|---|---|---|---|---|---|---|---|---|---|
| Clutch or Litter Size | 3.0 | average clutch size | eggs/clutch | Female | Adult | 12 nests | Hanford Site, Benton and Franklin Counties | Exposure Factor Datasets | 0.56 |
| Hatching Success | 2.67 | average number of young hatched | hatches/nest | Not Reported | Nestling | 12 nests | Hanford Site, Benton and Franklin Counties | Exposure Factor Datasets | 1.09 |
| Fledging or Weaning Rate | 2.67 | average number of young fledged | fledglings/nest | Not Reported | Fledgling | 12 nests | Hanford Site, Benton and Franklin Counties | Exposure Factor Datasets | 1.09 |
| Population Density | range of numbers of nesting pairs counted annually on a 1476 sq km study site | pairs/study site | Both Male and Female | Adult | 4 years | Hanford Site, Benton and Franklin Counties | Exposure Factor Datasets | ||
| Population Density | range of numbers of individual owls counted annually on a 1476 sq km study site | individuals/study site | Both Male and Female | Adult | 4 years | Hanford Site, Benton and Franklin Counties | Exposure Factor Datasets |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type | Error |
|---|---|---|---|---|---|---|---|---|---|
| Time of Nesting | mid-Feb to Jun 20 | period from first territory selection to last brood fledged | Both Male and Female | Adult | 15 nests | south-central Montana | Exposure Factor Datasets | ||
| Fledging or Weaning Rate | 64% | percent of nests known to fledge young | Not Reported | Fledgling | 11 nests | south-central Montana | Exposure Factor Datasets | ||
| Hatching Success | 100% | percent of eggs hatched in nests that produced young | Not Reported | Nestling | 11 nests | south-central Montana | Exposure Factor Datasets | ||
| Clutch or Litter Size | 2.2 | eggs/clutch | Female | Adult | 6 nests | south-central Montana | Exposure Factor Datasets | 0.2 SE |
| Exposure Endpoint Type | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type |
|---|---|---|---|---|---|---|---|
| Home Range | home range size (minimum convex polygon model) as determined by radiotelemetry | ha | Not Reported | Not Reported | 22 owls | Exposure Factor Datasets |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type | Condition | Lab |
|---|---|---|---|---|---|---|---|---|---|---|
| Foraging Distance | 0.25 | typical maximum distance between two roosting sites | mi | Both Male and Female | Adult | 11 home ranges | Superior and Ann Arbor townships | Exposure Factor Datasets | ||
| Population Density | 1 | bird/2000 acres | Both Male and Female | Not Reported | 11 owls | Superior township | Exposure Factor Datasets | |||
| Dietary Composition | white-footed mice (58.2%), meadow mice (28.0%), other small mammals (2.8%), medium sized mammals (5.1%), gamebirds and sm-med sized birds (4.8%), other birds (1.2%) | percent occurrence of prey items in pellets | Not Reported | Not Reported | 297 pellets from 14 owls | Superior township | Exposure Factor Datasets | |||
| Time of Nesting | Mar 12 - Jun 4 | period from earliest egg laying date to date of latest brood departure | Both Male and Female | Adult | 4 nests | Jackson Hole | Exposure Factor Datasets | |||
| Time of Hatching or Parturition | Apr 14 | earliest hatching date | Not Reported | Nestling | 4 nests | Jackson Hole | Exposure Factor Datasets | |||
| Population Density | 1 | density of nesting pairs | pair/3 mi^2 | Both Male and Female | Adult | 4 nests | Jackson Hole | Exposure Factor Datasets | ||
| Clutch or Litter Size | 2.2 | eggs/clutch | Female | Adult | 4 nests | Jackson Hole | Exposure Factor Datasets | |||
| Hatching Success | 11 | percent of eggs that failed to hatch | Not Reported | Nestling | 4 nests | Jackson Hole | Exposure Factor Datasets | |||
| Fledging or Weaning Rate | 2 | number of fledglings produced per pair | fledglings/pair | Not Reported | Fledgling | 4 nests | Jackson Hole | Exposure Factor Datasets | ||
| Territory Size | observed range of movement during nesting, based on observations of individual or pair movements | mi^2 | Not Reported | Adult | 4 birds | Jackson Hole | Exposure Factor Datasets | |||
| Dietary Composition | white-footed mice (3.6%), meadow mice (64.5%), shrews (0.3%), weasels (0.6%), red squirrel (0.3%), pocket gopher (23.5%), snowshoe rabbit (2.8%), ruffed grouse (1.4%) sage grouse (0.3%), mallard (0.6%), sm-med sized birds (1.4%), sucker (0.8%) | percent occurrence of prey items in diet during nesting | % | Not Reported | Not Reported | 361 food items, 4 nests | Jackson Hole | Exposure Factor Datasets | ||
| Food Ingestion Rate | averages of food amounts eaten per day | g | Both Male and Female | Not Reported | 2 birds | Exposure Factor Datasets | captive | Laboratory |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type | California Counties |
|---|---|---|---|---|---|---|---|---|
| Dietary Composition | Neotoma fuscipes (7.9%), Thomomys bottae (20.7%), Mus musculus (25.0%), Microtus californicus (14.9%), Reithrodontomys megalotis (1.7%), Perognathus sp. (4.1%), Dipodomys agilis (4.3%), Peromyscus sp. (3.8%), Notiosorex crawfordi (0.3%), Sylvilagus sp. (0.8%), Sorex ornatus (0.1%), Scapanus latimanus (0.7%), Stenopelmatus sp (2.1%), Elgaria multicarinata (0.1%), unident. birds (4.3%) | percent of total number of specimens identified in pellets | Not Reported | Not Reported | 25 lbs of pellets | Univ. of Calif., Los Angeles campus | Exposure Factor Datasets | Los Angeles |
| Dietary Composition | Neotoma fuscipes (11.3), Thomomys bottae (36.2), Mus musculus (14.0), Microtus californicus (13.5), Reithrodontomys megalotis (8.7), Perognathus sp. (7.8), Dipodomys agilis (3.1), Peromyscus sp. (3.1), Notiosorex crawfordi (1.3), Sylvilagus sp. (0.5), Sorex ornatus (0.5) | percent of total number of specimens identified in pellets | Not Reported | Not Reported | Not Reported | Santa Monica Mountains (1 ledge) | Exposure Factor Datasets |
| Exposure Endpoint Type | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type | Lab |
|---|---|---|---|---|---|---|---|---|
| Body Weight - Mean | maximum body weights achieved by captively raised chicks | oz | Not Reported | Juvenile | 2 birds | captured in Kansas | Exposure Factor Datasets | Laboratory |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type | Countries |
|---|---|---|---|---|---|---|---|---|
| Survival/ Mortality | 31% | mean annual mortality after the first year of banding based on band return data, 1951-1962 | Not Reported | Both Adults and Juveniles | 97 birds | Exposure Factor Datasets | CANADA, USA | |
| Survival/ Mortality | 46% | mean percent mortality within the first year of banding based on band return data, 1951-1962 | Not Reported | Juvenile | 97 birds | Exposure Factor Datasets | CANADA, USA |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type | California Counties |
|---|---|---|---|---|---|---|---|---|---|
| Population Density | density based on call counts | birds/2000 ac | Both Male and Female | Both Adults and Juveniles | 7 counts | San Joaquin Experimental Range | Exposure Factor Datasets | Madera | |
| Dietary Composition | cottontail (61.1%), woodrat (17.9%), kangaroo rat (4.5%), pocket gopher (4.3%), gopher snake (3.7%), ground squirrel (2.4%), other spp (birds, reptiles, amphibians, invertebrates; 6.1%) | percent occurrence by weight in pellets | Not Reported | Not Reported | 654 pellets, 1471 prey items | San Joaquin Experimental Range | Exposure Factor Datasets | Madera |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type |
|---|---|---|---|---|---|---|---|---|
| Population Density | pairs/mi^2 | Both Male and Female | Adult | 12-22 pairs (3 study years) | southern Green County | Exposure Factor Datasets | ||
| Time of Mating/ Laying | Feb 5-15 | peak period of egg laying | Female | Adult | 11-17 nests (3 study years) | southern Green County | Exposure Factor Datasets | |
| Fledging or Weaning Rate | mean number of fledglings produced per successful nest | fledglings/nest | Not Reported | Fledgling | 11-17 nests (3 study years) | southern Green County | Exposure Factor Datasets |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type |
|---|---|---|---|---|---|---|---|
| Dietary Composition | meadow vole and jumping mouse (11.3%), juv. white-tailed jackrabbit (9.4%), horned or eared grebe (5.7%), American coot (22.6%), sora and Virginia rails (3.8%), duck (26.4%), sharp-tailed grouse (9.4%), blackbird (11.3%) | relative frequency of prey species occurence in nests | Not Reported | Nestling | 78 nest visits | Lostwood National Wildlife Refuge | Exposure Factor Datasets |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type | Lab |
|---|---|---|---|---|---|---|---|---|---|
| Body Weight - Mean | 914.2 (pallascens), 991.7 (pacificus), 1154.3 (occidentalis), 1317.8 (virgianus), 1238.6 (wapacuthu) | Body weight means for 5 subspecies | g | Male | Adult | 10-26 individuals/subspecies | Exposure Factor Datasets | Laboratory | |
| Body Weight - Mean | 1142.2 (pallascens), 1312.4 (pacificus), 1555.1 (occidentalis), 1768.5 (virgianus), 1556.0 (wapacuthu) | body weight means for 5 subspecies | g | Female | Adult | 12-29 individuals/subspecies | Exposure Factor Datasets | Laboratory |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type | Countries | Error |
|---|---|---|---|---|---|---|---|---|---|---|
| Home Range | 24.8-26.1 | mean home range size of nonterritorial individuals in 1990 and 1991 | square km | Both Male and Female | Adult | 6 (1990), 8 (1991) | Kluane Lake (60 deg57'N, 138deg12'W), Yukon | Exposure Factor Datasets | CANADA | |
| Territory Size | 4.83 | mean territory size of territorial pairs | square km | Both Male and Female | Adult | 16 territories | Kluane Lake (60 deg57'N, 138deg12'W), Yukon | Exposure Factor Datasets | CANADA | 0.40 SE |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Sex | Life Cycle Stage | Sample Size | Location | Type | Countries |
|---|---|---|---|---|---|---|---|---|
| Dietary Composition | rodents (98.5%), birds + insects + reptiles + lagomorphs (1.5%) | percent of prey types in diet (seasonal average) | Not Reported | Adult | 522 pellets | near Bariloche, northwest. Patagonia | Exposure Factor Datasets | ARGENTINA |
| Exposure Endpoint Type | Endpoint Value | Endpoint Description | Units | Sex | Life Cycle Stage | Sample Size | Location | Type |
|---|---|---|---|---|---|---|---|---|
| Clutch or Litter Size | 1-4 | brood size at the time of banding | young/nest | Not Reported | Juvenile | 906 nests | near Cincinnati | Exposure Factor Datasets |
| Hatching Success | 47.3% | percent of nests with at least one young surviving to banding age (of all pairs observed) | Not Reported | Juvenile | 1777 territories | near Cincinnati | Exposure Factor Datasets |
