Land Bird Monitoring Protocols for National Parks in Alaska

Fieldwork was conducted in Denali National Park and Preserve by Alaska
Bird Observatory. In 1996, three observers determined seasonal variation in
detection probabilities for breeding birds in the park by conducting 18
BBS-style counts on one On-road route and obtained further estimates of the
interannual differences in relative abundance of breeding land birds in the park
by resurveying nine Off-road Routes that were surveyed in 1993, 1994, and 1995,
and resurveying all four BBS-style routes. Eighty-six taxa were detected in
1996 during systematic surveys, compared to 86 taxa in 1994, and 80 taxa in
1995. As in past years, the greatest species richness was found on the west side
of the park, where a wide variety of habitat types exist including some of the
only palustrine and lacustrine wetland habitat. Interannual variation data
collected from On-road Routes (Breeding Bird Survey-style censuses) showed
similar population trends as during Off-road Routes. The abundance of species
that were rare (occurred at <2% of all counting stations) tended to fluctuate
widely between years, often rare species were not detected in some years. In
contrast, the populations of species that were common and widespread exhibited
little annual variation, which is a pattern that previous studies in this region
of Alaska have found. White-winged Crossbill numbers were relatively low in
1996 during On-road Routes, while Orange-crowned Warbler abundance was greater
than in previous years. There was significant seasonal variation in detection
probabilities for a number of species. For example, Willow Ptarmigan (a
permanent resident) had high detection probabilities only during the first half
of May. Most Nearctic migrants arrived in the park by early May, while many
short-distance Neotropical migrant species did not arrive until 1 June.
Long-distance Neotropical migrant numbers did not peak until 9 June in 1995.
Paleotropical migrants (primarily Arctic Warbler) were the last migrants to
arrive in the Park, with the first detections on 10 June. Species richness
started to decline by 26 June. The peak survey period in the park extended from
10-25 June, as was suggested by the Boreal Partners in Flight working group.
Assuming one were attempting to monitor avian populations in Denali NPP with a
90% probability that were detected at > 14% of all survey stations could be
adequately monitored with 100 independent counting stations sampled each year.
On Off-road Routes in spruce-dominated habitats, 11 taxa met these power
calculations criteria in both 1994 and 1995 (Gray Jay, Swainson's Thrush,
American Robin, Varied Thrush, Orange-Crowned Warbler, Yellow-rumped Warbler,
Wilson's American Tree Sparrow, White-crowned Sparrow, Dark-eyed Junco, and
Redpoll sp.). These 11 taxa represent a broad array of migration strategies
(e.g., permanent residents, long-distance and short-distance Neotropical
migrants, nearctic migrants, and boreal migrants), and should be emphasized for
detailed monitoring scheme. Both Off- and On-road routes should continue to be
conducted in future years. The minimum amount of sampling that should be
conducted on the same nine Off-road Routes (108 total stations) that have been
surveyed since 1993; each survey station needs to be visited once per season.
In addition, although using frequency (i.e., the proportion of stations with
detections) is the primary analysis tool used in this report, we strongly urge
that total counts (i.e., the total number of individuals detected at each
station) continue to be collected at all survey stations. Virtually all other
monitoring programs use total counts to monitor interannual variation in avian
abundance, therefore data have to be collected in a format that is comparable to
other similar programs.

Geographic Description: Denali National Park and Preserve is located in the
central Alaska Range, approximately 210 km southwest of Fairbanks, Alaska. The
study area encompassed the Road Corridor which is 1 km on either side of the
main park road, 150 km long and extending westward from the park entrance at the
Parks Highway (63.73, 148.92) to the airfield near Kantishna (63.53, 151.00).
1.5.2 Bounding Rectangle Coordinates

Methodology: Two survey methods were used - Off-road and On-road Routes, to
compare avian abundance estimates among years. Off-road Routes sampled birds
only in spruce forests in the Park, whereas On-road Routes sampled all habitat
types along the Park road corridor. Off-road routes. -- This technique followed
the methodology developed by an Alaska Partners in Flight working group.
Off-road Routes were 12 point-count stations spaced approximately 250 m apart.
One observer surveyed one route per morning by walking between points. These
Routes were located only in spruce forest dominated habitats. Forests were
defined as habitats where trees (i.e., single-stemmed woody plants >3 m in
height) comprised > 10% of the crown cover (Viereck et al. 1992). Forest stands
were <0.8 km. from the park road to ease access and had to be large enough to
contain the Route (i.e., 2.75 km long by 0.5 km wide). All birds detected at an
unlimited distance from counting stations were recorded for a 5-minute period
(Blondel et al. 1981, Ralph 1993). Data were subdivided into the number of
detections before and after 3-minutes had elapsed. Detection cues were separated
into singing, calling, visual, and flying overhead. Detections were further
subdivided into those <50 m from counting stations and those >50 m. In 1996, we
resurveyed all nine Off-road Routes censused in 1993, 1994, 1995; this resulted
in 108 counting stations surveyed. Four of the Routes were located at the east
end of the Park road corridor, three were near the middle of the Park, and two
were on the west end of the park. Each Route was surveyed only one time per
breeding season. Two observers were used for these surveys in 1996, one of whom
had conducted observation variation surveys in Denali in 1995. Following
guidelines suggested by Verner and Ritter (1986, Dawson 1981), surveys were
initiated at official sunrise and took approximately 3 hours to complete.
Habitat characteristics at each counting station were quantified following a
protocol developed by an Alaska Partners in Flight working group (Handel 1993).
Data recorded within 50 m of each counting station included: elevation, aspect,
slope, presence and type of water (e.g., pond, river), tree canopy height, % of
coniferous trees, % of total tree cover, dominant shrub height, % of total shrub
cover, dominant shrub species, dominant ground cover. The primary objective of
this habitat analysis was to classify each counting station into habitat
categories developed by both Kessel (1979) and Viereck et al. (1992). On-road
routes - This technique utilized a methodology developed for the Breeding Bird
Survey (BBS) (Droege 1990). Censuses were conducted along three 39.4 km (24.5
mile) routes and one 29.8 km (18.5 mile) route. Fifty census stations were
located along each route, with the exception of the 36 stations on Route #4 (39
stations in 1993, and 37 stations in 1994 and 1995; only 33 stations were
surveyed on 6/19/96). Counting stations were spaced 0.8 km (0.5 miles) apart and
observers drove between stations, with observers surveying one route per
morning. Detections included birds heard (recorded as either singing or
calling) or seen from counting stations for a three-minute census period. Birds
were recorded at an unlimited distance from counting stations for a three-minute
census period. Birds were recorded at an unlimited distance from counting
stations. Routes were initiated 1/2 hour before official sunrise, or no earlier
than 3:30 AM and took 4-5 hours to complete.