More info for the terms: cover, crown fire, density, frequency, indicator value, ladder fuels, natural, prescribed fire, severity, shrub, stand-replacing fire, succession, tree, underburn, wildfire
Modifications in the food supply and habitat of gray jays may occur following fire, as well as changes in the abundance of competitors and predators [95]. According to Finch and others [33], the effects of fire on birds and their habitat vary with: 1) the severity and extent of the fire; 2) temporal scales; 3) life history characteristics of the bird species; and 4) whether or not salvage logging occurs following fire. Severe fires alter the forest structure more than low-severity fires, and a stand-replacing fire may result in the successional replacement of a bird species with a different bird species. Large, severe fires may greatly alter bird habitat in the short term but may be necessary for long-term maintenance of some forest types [58]. Fire may be beneficial to cavity-nesting, timber-drilling, grain-collecting, and fly-catching birds due to increased nesting habitat and food supplies [18,19,24,45,50,58,111,119]. Salvage logging may reduce the benefits of fire to birds that utilize snags for cavity nesting and foraging [58].
A meta-analysis of studies of bird responses to fire showed that gray jays and other bird species that share the same nest type, nest layer, and foraging guild do not show a distinct positive or negative response to fire. The analysis is shown below; the table does not distinguish between fire types (wildland, prescribed, stand-replacing, understory, various severities), vegetation types, or time since fire [98]:
Response to fire (% of studies) n positive negative none mixed Nest type: Open-cup nest 544 29 23 39 9 Nest layer: Canopy nest 423 31 18 42 9 Foraging guild: Omnivore 296 32 21 37 9
Gray jays are usually present in postfire habitats after fires of varying severities but experience lower abundance in burned than unburned areas. Results of studies examining gray jay responses to wildfire, prescribed burning, logging versus burning, and salvage logging follow.
Wildfire: Changes in bird abundance and species composition following mixed-severity wildfires were studied in low-elevation ponderosa pine/Douglas-fir habitat and mid-elevation mixed-conifer and lodgepole pine habitats in the Bitterroot National Forest in west-central Montana. In July and August 2000, dry lightning storms ignited fires of 99 to 135,900 acres (40-55,000 ha) in size; the fires ranged from low-severity to severe. Transects had been established in 1994 and 1995 before the wildfires occurred, and 1 year following the fires, burned and unburned transects of differing fire severities were compared. The mean relative abundance (number of gray jays detected within 100 m/point à 100 ± standard error) for gray jays was lowest following fire [109,110]:
Mean relative abundance ± s x
Before fire
After fire
Unburned points (n=120) 9.8 ± 2.2 8.1 ± 2.1 Burned points (n=122) 12.4 ± 2.7 4.2 ± 1.5
Gray jays were ubiquitous in various successional portions of lodgepole pine and Engelmann spruce-subalpine fir forests following wildfires in Grand Teton and Yellowstone National Parks, Wyoming; however, they were most abundant in severely burned areas 43 and 44 years following fire, which is typically when the canopy closes following severe wildfire. Ten areas were sampled in both Parks ranging from 1 to 304 years after fire and 40 to several hundred acres in size. In Grand Teton National Park, unburned, moderately burned, and severely burned areas were examined. In moderately burned areas, 40% or more of the tree understory was alive 1 year following the fire, and part of the grass-forb-shrub understory was unburned. In severely burned areas, all aboveground vegetation was killed by a severe crown fire. In Yellowstone National Park, all sampling areas were severely burned in 1667 and 1956 [119].
Gray jay densities were highest in unburned versus burned lodgepole pine and Engelmann spruce-subalpine fir forests in Yellowstone National Park, Wyoming. In 1974, the Trail Creek Wildfire burned 581 acres (235 ha) of 250-year-old lodgepole pine forest with an understory of Engelmann spruce and subalpine fir. In 1976, the Divide Wildfire burned 1,601 acres (648 ha) of 350+ year-old Engelmann spruce-subalpine fir forest. Fire severities were not documented. Avian communities were surveyed in 1978 and 1979 [83].
Gray jays preferred the ecotone and unburned areas of subalpine lodgepole pine forest 8 years following a high-severity wildfire on the Roosevelt National Forest, Colorado. The fire burned approximately 470 acres (190 ha), killing or top-killing virtually all aboveground vegetation. The total number of gray jays recorded on 6-point counts on three 49 acre (20 ha) plots is shown below [94]:
Total number of gray jays (and no. of territories)/ plot
Burned Ecotone Unburned 0 10 (2) 5 (1)
A literature review reported that gray jays were more abundant on unburned sites than on 23 severely burned conifer forests in the western United States [63].
Canopy cover did not predict distribution of canopy foragers such as the gray jay between burned and unburned lodgepole pine forests in Grand Teton National Park. Two-year postfire and six-year postfire sites were compared with unburned sites. Details about the size and severity of the fires were not given. Gray jays utilized the 2-year burns, 6-year burns, and unburned sites most during the postbreeding season. The mean frequency of observations during the breeding and postbreeding season of the gray jay is shown below [108]:
Mean frequency of observations à 100 (frequency of observations)
Treatment
Postfire year 2
Postfire year 6 unburned Breeding season 4 (3) 5 (3) 2 (1) Postbreeding season 36 (17) 13 (5) 28 (8)
Prescribed burning: Bock and Bock [20] studied the effects of prescribed fire on birds in ponderosa pine forests in the southern Black Hills, South Dakota. One area was burned in October 1979, covering 156 acres (63 ha). Another study area was burned in April and May 1980, burning 806 acres (326 ha). Both burns were low-severity in local isolated spots. Point counts were conducted in June 1980 and June 1981 on burned and unburned plots. Gray jay abundance was greatest on unburned plots for both years [20]:
Mean no. of breeding birds Year Burned Unburned 1980 0 0.7 1981 0.1 0.7
Logging versus wildfire: Clearcutting and stand-replacing fire both lead to early-successional forest; however, they do not provide the same habitat conditions [53]. Clearcuts and wildfires are distinct from each other for several reasons: 1) logging causes greater site disturbance due to road construction and logging equipment; 2) logging removes stems from a site; 3) wildfire leaves live residual stands, burned trees, and downed woody debris; 4) wildfire size, frequency, and distribution are different from cutblocks; and 5) wildfire is not predictable and does not target the most valuable trees [58]. Nevertheless, research comparing gray jays on logged and burned sites does not show any clear pattern of preferences.
Bird communities were compared between burned and harvested sites in a quaking aspen-dominated boreal mixed-wood forest in north-central Alberta. Three replicate stands were chosen from each class (1,14, and 28 postdisturbance years) and treatment (wildfire vs. harvest). More than 95% of the canopy trees were dead on burned sites. An average of 6% of preharvest trees remained on the harvested sites. Gray jay density was greater within 14-year-old postfire stands than in postharvest stands. Gray jays may have been responding to differences in the herb and shrub strata between postfire and postharvest stands [53]:
Density of gray jays (mean number of individuals (± s x)/25acres) Postdisturbance year 1 14 28 Postfire 0.7 ± 0.7 4.3 ± 2.0 1.3 ± 0.3 Postharvest 1.7 ± 0.9 0.0 ± 0.0 0.0 ± 0.0
Avian response to forest management practices was examined in mature ponderosa pine forests mixed with Douglas-fir or grand fir (Abies grandis) in Montana. Three site categories were chosen: 1) control sites containing either ladder fuels or encroachment by small- or medium- diameter trees; 2) treated sites that had been logged, underburned, or a combination of the 2 to reduce fuels and create open structural conditions; and 3) sites with a natural underburn in 2000. Gray jays were present in all 3 sites but most abundant in the control [133].
In northwestern Lac Saint Jean, Quebec, gray jays showed no significant (P>0.05) difference in abundance in postfire and postlogging stages in stands formerly dominated by black spruce [59].
Avian abundance was compared in wildfire and clearcut areas in a former black spruce forest near Goose Bay, Newfoundland after 5,14, and 27 years of succession. Details about the size and severity of the burn were not documented. Gray jay was not a common species in the study area but may have slightly preferred clearcut plots over burned plots [107].
Schulte and Niemi [100] surveyed bird communities in early-successional forests following logging and fire near Tower, Minnesota. Logged sites had been clearcut and contained residual trees and residual patches of trees. Wildfire sites were dominated by quaking aspen, and 5,189 acres (2,100 ha) of forest had burned. Logged sites were chosen to match the time of disturbance, predisturbance type, and soils of the burned sites. According to the vegetation analysis, habitat heterogeneity was greater in burned areas. The gray jay was 1 of 5 bird species highly associated with snags in this study; snags were probably utilized for foraging. Gray jay abundance did not differ significantly between logged and burned sites [100]:
Gray jay abundance (territorial males/ha)
Mean
s x P value Logged 0.02 0.02 0.12 Burned 0.10 0.06
Salvage logging: Resident species such as the gray jay were less likely to be detected in salvaged areas of a burned mixed-wood forest (dominant trees were white spruce and quaking aspen), a jack pine forest, and a quaking aspen forest near Meadow Lake, Saskatchewan than in logged areas. In 1995, a wildfire burned 98,840 acres (40,000 ha), killing a majority of the trees in the burned areas. Salvage logging took place in 1997. In 1998, surveys were conducted in unburned, burned, and salvaged forests. The indicator value of gray jay for each treatment in the 3 habitat types is shown below [76]:
Habitat type Indicator value (% ) Unburned Burned Salvaged P Mixed-wood 36 41 24 0.999 Jack pine 34 22 1 0.106 Quaking aspen 0 17 not salvaged 0.468
The following table provides fire return intervals for plant communities and ecosystems where the gray jay is important. For further information, see the FEIS review of the dominant species listed below.
Community or Ecosystem Dominant Species Fire Return Interval Range (years) silver fir-Douglas-fir Abies amabilis-Pseudotsuga menziesii var. menziesii >200 grand fir Abies grandis 35-200 [6] tamarack Larix laricina 35-200 [81] western larch Larix occidentalis 25-350 [7,14,30] Great Lakes spruce-fir Picea-Abies spp. 35 to >200 northeastern spruce-fir Picea-Abies spp. 35-200 [31] Engelmann spruce-subalpine fir Picea engelmannii-Abies lasiocarpa 35 to >200 [6] black spruce Picea mariana 35-200 conifer bog* Picea mariana-Larix laricina 35-200 [31] pinyon-juniper Pinus-Juniperus spp. <35 [81] whitebark pine* Pinus albicaulis 50-200 [2,5] jack pine Pinus banksiana <35 to 200 [28,31] Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-340 [13,14,118] Colorado pinyon Pinus edulis 10-400+ [35,40,61,81] Sierra lodgepole pine* Pinus contorta var. murrayana 35-200 Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 [6] interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [6,11,66] red pine (Great Lakes region) Pinus resinosa 3-18 (x=3-10) [27,38] red-white pine* (Great Lakes region) Pinus resinosa-P. strobus 3-200 [28,48,70] eastern white pine Pinus strobus 35-200 eastern white pine-eastern hemlock Pinus strobus-Tsuga canadensis 35-200 [125] aspen-birch Populus tremuloides-Betula papyrifera 35-200 [31,125] quaking aspen (west of the Great Plains) Populus tremuloides 7-120 [6,41,74] Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [6,8,9] coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [6,77,90] redwood Sequoia sempervirens 5-200 [6,34,115] western redcedar-western hemlock Thuja plicata-Tsuga heterophylla >200 western hemlock-Sitka spruce Tsuga heterophylla-Picea sitchensis >200 [6] *fire return interval varies widely; trends in variation are noted in the species review