|
|
Mean (SD) |
|
|
|
|
|
Habitat variable
|
Description
|
Presence |
Absence |
Reason for inclusion/exclusion
|
|
Lake area |
Lake surface area, excluding islands (ha) |
209 (1125) |
33 (34) |
Included: loons prefer larger lakes for a variety of reasons |
Lake perimeter |
Lake shoreline length (km) |
11 (23) |
4 (3) |
Excluded: correlated with lake area |
Lake shape |
Lake configuration and shoreline complexity |
2 (1) |
2 (1) |
Excluded: correlated with lake area and perimeter |
Maximum depth |
Maximum lake depth (m) |
14 (11) |
6 (4) |
Included: important for fish/prey habitat |
Islands |
Number of islands per lake |
4 (13) |
1 (2) |
Included: loons prefer small islands for nesting |
Elevation |
Lake elevation (m) |
296 (154) |
251 (152) |
Included: estimate of geographic specification |
Lake flushing rate |
Total volume of water entering a lake per unit time (m³/yr) divided by lake
volume (m³) |
12 (43) |
39 (82) |
Included: important factor in nest survivorship |
Water clarity |
Secchi depth transparency reading (m) |
4.5 (2.1) |
2.6 (1.2) |
Included: loons are visual predators |
Total phosphorous |
Organic and inorganic forms of phosphorus (mg/L) |
0.009 (0.005) |
0.017 (0.011) |
Included: estimate of human disturbance |
pH |
Hydrogen ions in the water or acidity (units) |
6.6 (0.4) |
6.4 (0.6) |
Included: indicator of fish habitat |
Trophic status |
Categorical: 1 = oligotrophic, 5 = mesotrophic, 10 = eutrophic |
3 (3) |
6 (3) |
Excluded: correlated with phosphorous |
Conductivity |
Number of ionic particles present (µmhos/cm) |
48 (33) |
66 (53) |
Excluded: negatively correlated with clarity |
Loon distance metrics |
Distance to nearest loon presence lake (upper numbers) and distance to nearest loon
absence lake (lower numbers, km) |
2 (2.4) 6 (4.5) |
5 (5.2) 5 (4.2) |
Included: hypothesized loon dispersal factor |
Developed-residential/urban |
Proportion of residential and urban developed land within 150- and 500-m zones
surrounding each lake and nest/non-nest site (%) |
3 (4) |
4 (7) |
Included: estimate of human disturbance |
Agriculture |
Proportion of pasture, hay, and cultivated cropland cover within 150- and 500-m
zones surrounding each lake and nest/non-nest site (%) |
1 (2) |
2 (3) |
Included: estimate of human disturbance |
Forested |
Proportion of forested land cover within 150- and 500-m zones surrounding each lake
and nest/non-nest site (%) |
36 (13) |
45 (17) |
Included: hypothesized habitat factor |
Wetland |
Proportion of forested and nonforested wetland cover within 150- and 500-m
zones surrounding each lake and nest/non-nest site (%) |
4 (7) |
10 (13) |
Included: hypothesized habitat factor |
Open water |
Proportion of open water with < 25% vegetation or soil within 150- and 500-m zones
surrounding each lake and nest/non-nest site (%) |
54 (12) |
35 (13) |
Included: hypothesized habitat factor |
Cleared and disturbed |
Proportion of cleared or disturbed land within 150- and 500-m zones surrounding each
lake and nest/non-nest site (%) |
3 (4) |
4 (6) |
Excluded: correlated with Developed |
Road density |
Density of roads within 150- and 500-m zones surrounding
each lake and nest/non-nest site (m/m²) |
1798 (1255) |
2132 (1759) |
Included: estimate of human disturbance |
Minimum distance to human population center |
Minimum distance to high-density residential areas and municipal community centers
from nest/non-nest site (km) |
4 (4) |
3 (3) |
Included: estimate of human disturbance |