MOOSE TREND SURVEY SUMMARY 2021 Koyukuk/Nowitna/Innoko NWR Complex (Game Management Units 21A, 21B, 21D and 24D

We conducted aerial moose trend surveys on the Koyukuk/Nowitna/Innoko NWR from November 5-18, 2021. We completed four Trend Count Areas (TCAs) on the Koyukuk, one TCA on Innoko, two TCAs on the Nowitna, and three TCAs on the Kaiyuh (Northern Innoko). The State survey crew flew one TCA on the Koyukuk. Snow conditions this year were excellent (6”-8” on the ground) everywhere in all TCAs. Temperatures were mostly average (-22 to

+25°F) throughout the survey. Sightability was good or excellent most days because of high overcast and adequate snow cover, though heavy frost created a “canopy” in dense brush and forested areas.

Last edited 03/02/2022

The population in the Pilot Mt/Galena/Koyukuk River Mouth area remains healthy, though we observed a second year of lower calf production. The number of cows and bulls remain stable and healthy, and yearling bulls are in the low range of what we would consider “average”.

The Kaiyuh moose population (between Nulato and Kaltag) growth seems to be slowing or flattening out from the steady increase observed since 2011. Overall numbers of cows and bulls are still above the long-term average and yearling recruitment and calf production/survival to fall are good, but not as high as they had been a few years ago.

We recorded another low in the overall number of moose observed in the Nowitna River TCAs this survey season. Cow numbers were again below the long-term average. Overall bull numbers are better than last year’s low, though still below average. Calf production also was better than last year, but remains on the low-average. Yearling bull recruitment remains well below average also. Overall, the continued lower observations on the Nowitna is concerning.

The Innoko River (between the lower Dishna and Grouch Creek) appears to be a healthy, low density population. This year we again saw a decrease in cows and bulls observed. Last year we recorded a staggering zero calves, which none of us had ever seen before on a survey. This year, calf numbers were back up to average, which was a relief. Yearling bull observations decreased again, which was not surprising given the lack of calves last year. The downward trend in this population is concerning, though it is a low density population and variations tend to swing widely in low density populations.

The northern Koyukuk (Treat Island and Huslia Flats) adult cow numbers have been inching back up to the long-term averages (800) in recent years, though observations decreased slightly this year and are just below the average. Calf production increased and is back up to the long- term average. Bulls are at the long-term average, though yearling bull numbers were low again and are below average (medium and large bulls are both above average).  Considered separately, the Huslia Flats TCA has shown a consistent and stable adult population with annual variations in calf production, while Treat Island TCA seems to exhibit a similar stable bull population but shows a 20-year declining trend in cows. More moose than usual were observed in the Dulbi

Slough TCA to the south (between Treat Island/Huslia Flats TCAs and the Dulbi River TCA) while transitioning between TCA’s, which may indicate movement and distribution changes in the area.

The middle Koyukuk (3-Day Slough and Dulbi River) saw decreases in both bull and cow numbers, which were finally inching back up to the long-term averages last year. Calf numbers were observed to be at the long-term average, while yearling bulls remain higher and just above average. While flying the northeastern edge of Dulbi River, we observed large numbers of moose just over the line and in the adjacent Dulbi Slough TCA, which was not surveyed this year. Again, movement and distribution of moose may contribute to the lower number of moose observed this year in the Dulbi River TCA

Methods/Survey Areas

The Alaska Department of Fish and Game surveyed the Three-Day Slough TCA on the Koyukuk NWR (21D). USFWS crews surveyed the Koyukuk River Mouth, Dulbi River Mouth, Huslia River Flats, Treat Island TCA’s on the Koyukuk NWR (GMU 21D and 24D), Innoko River TCA on the Innoko NWR (GMU 21A), Kaiyuh Slough, Pilot Mt. Slough, and Squirrel Creek TCAs on the Northern Unit of Innoko NWR (Kaiyuh) (GMU 21D), and Nowitna River Mouth and Nowitna/Sulatna River Confluence TCA’s on the Nowitna NWR (GMU 21B).

Units were surveyed using three CubCrafter Top-Cubs. Pilots utilized for trend count surveys this year were; B. Scotton, E. Mallek, and N. Guldager. Observers included; J. Bryant, B. Pratt,

B. Nigus, and B. Rebarchik. Pilots used GPS location data to navigate the .25 mile transects and the observer recorded locations on a GPS and paper data sheets. Search intensity required is 7-8 minutes per square mile (or 38-44 minutes per unit), but varies depending on density of moose and habitat type (as little as 20 min. in open habitats and as much as 70 min. in closed habitats). The GSPE method does not specify a sightability correction factor as previously required by the Gasaway method. Research elsewhere in the state suggests that 10-25% of moose are not seen during this type of survey. Since these are a trend survey, methodology should be kept as consistent as possible so comparisons between years can be made directly. In normal snow years, search aircraft fly 9-12 transect lines per unit. Overall, we spent an average of 35.6 minutes per unit or 6.33 minutes per square mile surveying 242 units this year.


Koyukuk and Northern Unit of Innoko (Kaiyuh) NWRS:

Survey Timing and Conditions: We received good snow, consistent cool temperatures, and very little to no wind in mid October, followed by heavy frost in early November. We began surveys at Huslia Flats on November 5 with one airplane. Ed and Nikki (who came out to help again this year) flew out to Galena on the 8th and we had three planes surveying from the 9th until the 18th. We had the longest stretch of good weather and conditions ever during this year’s surveys and were able to finish all TCAs by November 18 – which in some years is when we start flying. We did encounter a few instances of ice fog/mist at Huslia Flats, Novi Mouth, Kaiyuh, and Innoko, but we were able to move around and keep working. All the TCAs had good to excellent snow cover and heavy frost in forested or shrubby areas. Snow depths were about 6-8 inches deep in most of the survey areas.

Treat Island and Hulsia Flats TCAs Combined, southern GMU 24:

These two combined TCAs cover a continuous area north/northeast of Huslia totaling 306 mi². Results from this year’s 2021 surveys indicate that adult cow numbers are a little below what we’ve seen the last three years and are just below the long-term average while bull numbers are back up near the long-term average again this year. Calf production/survival to fall was higher than the last few years, and is average. The bull:cow ratio is above average at 41 bulls:100 cows (Table 1, Figs. 1, 2, & 3). Recruitment decreased in the last three years and is below average at 6 yearling bulls:100 cows. Snow conditions were good to excellent this year, though the number of cows and yearling bulls still declined, probably due to movement or the high snow levels last winter. We did not see a large decline in calf numbers, which is promising for next year’s count. When the two TCAs are considered separately, Huslia Flats is performing much better than Treat Island. The two areas are adjacent to each other, but Huslia Flats shows consistent cow numbers, increasing bulls, and excellent calf production. Conversely, Treat Island has seen a steady decrease in moose density at an average annual rate of -7%. Calf production and yearling recruitment at Treat has also been consistently lower than at Huslia Flats. We do know that movement and distribution affect the annual counts in these TCAs, but the long-term trend appears to show a decline in overall density and productivity at Treat Island, relative to Huslia Flats.

Dulbi River Mouth and Three Day Slough TCAs Combined, GMU 21D:

The combined TCAs cover a discontinuous area (the two are not connected, but are within a few miles along the Koyukuk River south of Roundabout Mt.) totaling 277 mi². Total counts from this year’s survey decreased from last year’s improvements, though we still consider this area stable and slowly recovering from the decline observed in 2012. Cow and bull numbers have been inching back up to the long-term averages (Tables 2 & 3, Figs. 4, 5, & 6) and are finally both just above average again. Yearling bull observations were average for the second year and the yearling bull:cow ratio is good (above the long-term average at 9 yearling bulls/100 cows), but may be inflated some by the small decrease in cow observations. Calf numbers increased and calf production/ or survival of calves to fall (28 calves/100 cows) is excellent. The overall bull ratio is good for the second year at 28 bulls:cows, which is above the long-term average, due mainly to a slight decrease in cows coupled with a steady number of bulls in all three classification of yearling, medium, and large bulls observed. Snow conditions at 3-Day Slough and Dulbi River were excellent with heavy frost this year. We did observe large groups of moose in units just outside of the TCA’s this year, including bull aggregates, indicating that movement and distribution in and out of the trend count areas affect annual observation totals.

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