RMERF spring 2018 counts: Mount Lorette and Steeples March 1, Beaver Mines February 25-March 1

MOUNT LORETTE, BEAVER MINES and STEEPLES RAPTOR COUNTS

SPRING 2018

www.eaglewatch.ca

PETER SHERRINGTON

Introduction 2018 is the 27th consecutive year that a spring raptor count has been conducted at the Mount Lorette site. In 1992 an eight-day reconnaissance count starting on March 20 at the site established that Golden Eagles moved to the northwest in significant numbers through the Rocky Mountain Front Ranges. Most of the birds moved along the Fisher Range, crossing the Kananaskis Valley to Mount Lorette before continuing their migration to the northwest. A 48 day (393 hour) count at the site in the spring of 1993 yielded 4140 migrating Golden Eagles and the following year a seventy day (649 hour) count produced 4213 birds which remains the highest spring count ever for the species at Mount Lorette. Between 1994 and 2007 extensive spring counts averaging 82 days (897 hours) were conducted at the site with a maximum count in 2005 of 94 days (1238 hours). Despite the steady increase in observer effort during this period, the number of migrating Golden Eagles counted has steadily and significantly decreased since 1995. In 2006 RMERF conducted it first complete fall count at the Piitaistakis-South Livingstone site near the Crowsnest Pass in SW Alberta and in 2008-10 also conducted full spring counts there. During this period extensive comparative counts were made at Mount Lorette between March 1 and April 15 which is coincident with the height of the Golden Eagle migration and during which period over 90% of the population moves north. Observer effort from 2008-10 at Mount Lorette averaged 43 days (487 hours) with a maximum count of 46 days (519 hours) in 2010 when no days were lost to inclement weather. In 2011 and subsequent years the count period was extended by 1 week (March 1 to April 22) and we will use the same period this spring.

Last year’s (2017) spring count saw a combined species passage of 2672 birds that included a Golden Eagle count of 2256. The March combined species count of 2014 represented 89.3% of the total count, while April’s count of 290 was 47.4% below average, but the April total of 242 was 45.2% below average. The maximum Golden Eagle count was 363 on March 19 and 4 other days had counts exceeding 100 birds. Eleven species occurred in higher than average numbers: Bald Eagle (216), Northern Harrier (5), Cooper’s Hawk (9), Northern Goshawk (27), Broad-winged Hawk (3), Swainson’s Hawk (2), Red-tailed Hawk (70), Rough-legged Hawk (23), American Kestrel (4), Merlin (11), Gyrfalcon (3) and Peregrine Falcon (4). Only 3 species were below average: Sharp-shinned Hawk (16), Golden Eagle (2256) and Prairie Falcon (1). The combined species median passage date was March 20, 2 days earlier than average.

Last year saw the second complete (56 days) count at Beaver Mines which produced 1992 migrants of 18 species: 2 Turkey Vultures, 10 Ospreys, 304 Bald Eagles, 70 Northern Harriers, 71 Sharp-shinned Hawks, 14 Cooper’s Hawks, 72 Northern Goshawks, 15 Broad-winged Hawks, 3 Swainson’s Hawks, 214 Red-tailed Hawks, 7 Ferruginous Hawks, 68 Rough-legged Hawks, 1069 Golden Eagles, 6 American Kestrels, 18 Merlins, 5 Gyrfalcons, 11 Peregrine Falcons, and 9 Prairie Falcons. This year will be the fourth consecutive count at the site which is conducted from my house in Beaver Mines.

Vance Mattson’s 2017 15-day reconnaissance count at the Steeples site on the western flanks of the Rocky Mountains near Cranbrook, BC produced 515 birds of 8 species that included a record single day high count of 147 raptors (12 Bald Eagles, 133 Golden Eagles) on March 17. This year will be the eighth consecutive count at the site.

Rosemary and Cliff Hansen are organizing the Mount Lorette count and welcome visitors to the site. If you are interested in volunteering as a “Sky-sweeper” (no previous experience needed: just good eyes and binoculars) or as an Observer please contact Rosemary at rosemary.rmerf@gmail.com. Details of how to find the site and other useful information can be found on our website, www.eaglewatch.ca. Generally the best time to see migrating eagles is in the afternoon, and the chart below gives an indication of the dates when other raptors are expected to be moving at the site.

Sunday, February 25 Beaver Mines [Day 1] 1400-1800 (Peter Sherrington). Winter did not seriously arrive in the area until around 20 December, but when it did it has been characterized by generally below-average temperatures, persistent periods of heavy snowfall and downslope winds that have regularly gusted between 80 and 110 km/h. Daily road surveys conducted in the study-area yielded only 9 Golden Eagles during the whole of January but 26 were seen between February 7 and 25 indicating some early northward movement through the prairies. Short periods of observation from my house on February 12 and 20 produced 2 adult and 4 adult migrant Bald Eagles respectively, and the cumulative count for the road surveys for the year to date is an above average 257 birds. By contrast, wintering Rough-legged Hawks have been relatively scarce (36 in January, 31 in February), especially considering that we counted over 500 southbound migrants on the fall Vicki Ridge count. This probably reflects the persistent thick snow cover that makes the hunting of small mammals difficult. Other raptors have also been scarce with yearly totals to date of 1u Sharp-shinned Hawk (January 13), 1 adult Cooper’s Hawk seen on four occasions between January 28 and February 16, 5 Northern Goshawks, 1 adult light morph calurus Red-tailed Hawk seen in Beaver Mines on January 11 and 16, 1u Richardson’s Merlin, 2 adult male grey morph Gyrfalcons and seven sightings of single Prairie Falcons.

Today the temperature was -3C that fell to -5C at 1800, winds were W-WSW 20-35 km/h during the count period, but had been gusting to 80 km/h during the morning, cloud cover was 100% stratus all day and steady snow fell to 1400 when it became light, the ridge was visible and observation could begin. The snow finally ceased at 1645 after which an adult Bald Eagle was seen at 1707 and a dark morph Rough-legged Hawk at 1734: the first migrants of the official 2018 count.

4 hours (4) BAEA 1 (1), RLHA 1 (1) TOTAL 2 (2)

Monday, February 26 Beaver Mines [Day 2] 0800-1800 (Peter Sherrington). The temperature at 0800 was -8C, reached a high of -1C from 1100-1300 and was -4C at the end of observation. Winds in the morning were NW-W 10-15 km/h but were WSW in the afternoon 30-40 gusting 50 km/h causing blowing snow in the valley. Much of the day was cloudless, with a maximum of 20% scattered cumulus occasionally developing, which produced a very welcome sunny day. Despite the ideal migration conditions the first migrant and first Golden Eagle of the season (surprisingly a juvenile bird) did not move north until 1225 and thereafter migration was slow but steady with at least one eagle occurring each hour until the close: the last bird was an adult Bald Eagle at 1702. The final count of 7 birds was 3 adult Bald Eagles and 4 Golden Eagles (3a, 1j), not a bad day for late February.

10 hours (14) BAEA 3 (4), GOEA 4 (4) TOTAL 7 (9)

Tuesday, February 27 Beaver Mines [Day 3] 0800-1800 (Peter Sherrington). The temperature was -7C at 0800, the high was -2C from 1300-1500 and it was -5C at the end of observation. Winds were W-WSW all day 30-45 gusting 60 but reaching 70-80 km/h in the early afternoon and horizontal light snow originating near the continental divide to the SW persisted between 1100 and 1515, even when the sky was essentially cloudless. Cloud cover was 60-100% altostratus, altocumulus and cumulus for most of the day, but the edge of the downslope cloud cover occasionally retreated to the SW leaving clear skies. Observation conditions were good throughout but the first migrant, an adult Bald Eagle, was not seen until 1310 and only 5 more birds moved, 4 of which occurred between 1554 and 1636. The final count was 2 adult Bald Eagles, 1 light morph Rough-legged Hawk and 3 Golden Eagles (2sa, 1j). Non-migrant birds were 1 adult Northern Goshawk and 2 Golden Eagles (1a, 1j).

10 hours (24) BAEA 2 (6), RLHA 1 (2), GOEA 3 (7) TOTAL 6 (15)

Wednesday, February 28 Beaver Mines [Day 4] 0800-1800 (Peter Sherrington). At 0800 the temperature was -6C, the high was 0C at 1400 and it was -3C at 1800. Winds were again W-WSW all day, 10-30 km/h to 1030, 35-45 gusting 55 km/h to 1600 and 30-35 km/h for the final 2 hours. Cloud cover was 90-60% altostratus and cumulus in the morning that produced occasional snow flurries, and 20-30% cumulus throughout the afternoon that gave excellent observing conditions. A season-high total of 14 raptors moved slowly but steadily between 0946 and 1717 with the last 4 birds occurring between 1701 and 1717. The final count was 7 adult Bald Eagles, 1 light morph Rough-legged Hawk and 6 Golden Eagles (5a, 1j). One or two adult resident Golden Eagles were also present.

10 hours (34) BAEA 7 (13), RLHA 1 (3), GOEA 6 (13) TOTAL 14 (29)

Thursday, March 1 Mount Lorette [Day 1] 0830-1530 (Blake Weis, assisted by Cliff Hansen). The starting temperature was -7C, the high was -1C at 1100 and fell to -2C at 1530 when the count was abandoned for the day as steady snow fell. Ground winds were calm to light SE-SW in the morning and N-NNE 5-12 gusting 20 km/h in the afternoon, and ridge winds probably followed the same pattern. Cloud cover was 100% altostratus to 1000, 70-100% altostratus, cumulus and altocumulus to 1400 that allowed brief sunny breaks and 100% stratus and cumulus for the rest of the day that brought light to moderate snow that became steady after 1500.The east ridges were 70% obscured at the start but completely cleared between 1000 and 1100 before clouding over again to 90% by 1500. The west was initially 10% obscured which gradually increased and reached 90% at the end of observation. No migrant raptors were seen, but a resident Northern Goshawk called near the site at 0930 and 2 resident adult Bald Eagles perched by the river before flying low to the west. The only other birds seen were 1 Grey Jay, 6 Common Ravens and 2 American Dippers. Five visitors came to the site in the morning when the weather was quite pleasant.

7.5 hours (7.5) TOTAL 0 (0)

Thursday, March 1 Beaver Mines [Day 5] 0800-1800 (Peter Sherrington). The temperature at 0800 was -7C, the high again was 0C at 1100 and 1200 and winds were light (<10 km/h) W-NW in the morning, and ESE-E 15-20 km/h in the afternoon. Cloud cover was 80-100% altostratus and altocumulus in the morning that allowed hazy sunshine, and 100% stratus in the afternoon with light snow starting at 1540 that persisted for the rest of the afternoon although the ridge remained clear during the observation period. The only migrants seen were 3 adult Bald Eagles at 1137 that soared for several minutes above the ridge without gaining altitude in the light winds, before gliding low to the NW over the valley. A resident juvenile Golden Eagle soared briefly above the ridge at 1358, but no further migrants were seen.

10 hours (44) BAEA 3 (16) TOTAL 3 (32)

Thursday, March 1 Steeples [Day 1] (Vance Mattson) NO OBSERVATION (Weather). The mountains were obscured all day and snow is forecast for tomorrow.