Wednesday, July 10, 2019

Survey Period 2/2 RESULTS


Phillip Andrews
Great Gray Owl Surveys, Period 2 of 2
April 15-20
Delta Junction, AK

Main topics:
True sighting, repeat surveys, daytime surveys
No owls are seen or heard during the day (before sunset, after sunrise)

Two great grays were detected during this survey period, compared to none during the first. Each was heard, perhaps coincidentally, after the last of about 8 broadcast calls (via playback from speakers).
The first detection was at the last survey location on the first night (4/15), where the owl responded two minutes after the broadcast call. The species was identified by its calls: territorial and irritated hoots. This call was heard at 12:15 am. The owls’ location was determined using two points and triangulating towards the owl. This area was revisited the following day at 2:30pm after and the area was searched for two and a half hours, with no luck in relocating the individual or finding any signs of owl presence (nests, pellets, white-wash, etc.). Notes from the nest search: Many squirrels, pair of grosbeaks, bald eagle flying above, raven flying above. Possible owl flying 200ft. away. This area was great habitat. The environment was mostly tree cover adjacent to open brushland and surrounding pockets of meadows. Few witch’s brooms were found in the area. All of them were large but none were determined to be occupied except by squirrels. The call was played again at the end of the search, but received no response. This location was 0.6 miles away from the main road (Alaska Highway 2), along a dirt path and located within the Roughed Grouse Habitat Management Area, about 20 miles SE of the town of Delta.
The owl was likely hunting the night before in one of the open meadows [appendix 1 photos]. In the original written record of this event, I noted that part of the hooting sounded “concerned,” like the warning call of this species, with individual hoots rising slightly in pitch.
The second detection was at 3:40 am on 4/19. It was determined to be a great gray owl by its large size, large head, and slow-paced hoots. It flew 10 ft. in front of me, silently on a dark, cloudy night and I couldn’t see any color patterns in the feathers but the silhouette was characteristic of a great gray with a large head in comparison to its body. The hoots were single syllable and evenly spaced but seemed too slow even for a great gray and the tone was more like that of a great horned.
This area too, was searched the next evening at 8:00 pm for two hours for signs of owls. None were found. The habitat was not great for nesting and hardly looked decent for hunting- a small patch of dense, small to medium spruce trees surrounded by open meadow/ tussocks. This location was separated 0.17 miles from the main road (Richardson Highway) with light spruce cover and tussock-like meadow along the Trans-Alaska Pipeline and near a large clearing with overhead electrical lines [appendix 2 photos].
This owl was also likely hunting because of the low vegetation, but the only realistic perches available were a handful of trees in the exact area the owl was initially heard.
The call was played again with no response. Within the small spruce trees were a substantial amount of witch’s brooms, though all very small, and none appeared to be occupied by any animals.

For the revisit of each of these areas, a five-minute listening period was instigated to reduce the effects of surveyor presence on owl detection and disturbance.

Methods:
One 4 minute broadcast call was made in Audacity (version 2.2.2) and was composed to three types of calls: male territorial (typical “hoots”), a female begging call, and a chick begging call. Periods of silence were incorporated into the call to allow the observer to hear background-calling and responding owls.

Five minute calls were composed of:
1. 120 seconds of silence
2. 70 seconds of calls
               Male territorial, female begging, chick begging
3. 30 seconds of silence
4. 20 seconds of calls
               Male territorial, female begging
5. 60 seconds of silence

A total of 142 calls were performed, with 67% overlap with previous surveys and 47 new points this survey period, and 30 single points the first survey period, making a total of 95 repeat-visit surveys and  77 single-visit surveys.
Single visit surveys occurred because of environmental limitations such as wind and time of day.

One of the sightings was from a repeat-visit and one from a single-visit survey.


Other birds detected around the time of this survey period:

In Delta Junction:
1 Bald Eagle
~5 Boreal Owls (audial)
4 Black Capped Chickadees
1 Canada Jay (i.e. Gray Jays)
2 Goshawks, different locations, both hunting in meadows during the day.
2 Great Gray Owls (audial)
~6 Great Horned Owls (audial), one seen along Clearwater Rd. on the top of a telephone post scarfing down a small rodent.
1 Gull (Glaucous-winged?)
2 Pine Grosbeaks (pair)
2 Swans (unknown species) in formation, three different times and both night and day
1 Unknown small brown bird (<5 in. head to tail)
Between Delta and Fairbanks:
1 Bald Eagle, flying 15 ft. from the highway, in Salcha
2 swans (Trumpeter?)
2 ducks (Scaups?) 


Surveyors:
Phillip Andrews, Nastasia Caole


Appendix 1:
Meadow located within the direction of detection






Appendix 2:







Thursday, April 11, 2019

Species Identification for Surveyors



11 Important Species for Identification








Great Gray Owl
Calls, hoots, and begging sounds:





Great Horned Owl
Sounds:





Canada Jay (Gray Jay)





Common Raven





Three-Toed Woodpecker






Hairy Woodpecker      
          vs.        Downy Woodpecker



                        

    Black-Capped Chickadee     




Boreal Chickadee



      

Common Redpoll
                         



Hoary Redpoll


Photos and drawing attributions (left to right, down the page):
Ann Cook, Ron Kube, USFWS, Pekka Suopajarvi, USFWS, Pam Monacelli, Larry Hitchens, USFWS, Alexander Kolomietz, Jack Binch, Steve Calver, Roger Troy Peterson, Scott MArtin, Claude Nadeau, Eric Gofreed, Skye Haas


Wednesday, April 10, 2019

Survey Period 1/2 RESULTS


Phillip Andrews
Great Gray Owl Surveys, Period 1 of 2
March 12- 17
Delta Junction, AK

Main topics:
Effectiveness, wind, priority areas

Definitions:
Survey length- Dusk or dawn surveys, typically 3 hours.
Survey period- Surveys lengths over multiple days, 5 days in this case.
                                                                          
Methods:
One 4 minute broadcast call was created in Audacity (version 2.2.2) with calls of two Great Gray Owl (GGO) individuals. These calls were from 1) the Oregon BLM GGOW survey page “Male Series Hoot” (BLM 2018), and 2) a recording from Xeno-canto (rec # 233366). Calling was performed using a handheld speaker (FoxPro NX4). The cone speaker, rather than the horn was used to playback the calls and the volume was adjusted to suit wind severity and to allow the call to travel about ¼ of a mile.

Five minute calls were composed of:
1. 60 seconds of hoots in 5 segments (looped from the BLM recording)
2. 90 seconds of silence
3. 90 seconds of hoots in 4 segments (from xeno-canto)
4. 60 seconds of silence (timed by the researchers with their watches)

Survey sites were selected based on accessibility and were primarily along trails, pipelines and power lines. Some sites were close to main roads. Before travelling to Delta Junction, trails and roads were outlined in ArcGIS for further exploration. It is important to note that many potential routes were discounted because of private property (see map). However, between properties, occasional routes did exist and allowed for surveying. Surveys close to roads (within .5 miles) were avoided at night time to reduce the amount of road noise. One area stood out in particular when exploring potential survey sites. This was the Youth Bison Hunting Range located in southeast Delta Junction. It had extremely large meadows surrounded by medium to large evergreen trees. Only part of this area was surveyed due to high velocity wind.
Surveys were started the night of March 12th after arriving in Delta Junction that afternoon. The first surveys were performed about 15 miles east of the highway junction, along an OHV trail south of the Alaska Highway. On this first night, I, the primary investigator and my father performed surveys together to establish techniques to both adhere to for the remainder of the survey period (6 days). Wind picked up gradually and persisted throughout this survey period with intermittent calm weather. This drastically reduced our surveying ability. Based on the severity of wind speed (~ 10 miles per hour or above), surveys were either modified or cancelled all together. Modified surveys were either performed at a different time of day or their locations were moved to wind-protected areas, typically within a stand of trees. A total of 126 surveys over eight survey lengths were performed.
There was not much snow on the ground and skis and snowshoes were not necessary, though skis were used in some areas for quick travel on ice between survey points.

Results:
No Great Gray Owls were detected during this survey period.
Great Horned Owls were heard east of town on three separate occasions, at ten survey locations.
It is probable that these individuals were encountered on each of these locations because they were about one mile apart (and heard in triangulating directions from the two surveyors) but at least two individuals (m+f) were present in the area because of their concurrent calling.

Encounters:
Other species of wildlife encountered during surveys were:

  • ·        Woodpeckers (unknown spp.)
  • ·        Boreal Chickadees
  • ·        Black Capped Chickadees
  • ·        Common redpolls
  • ·        Common ravens
  • ·        Tree Squirrels
  • ·        Moose
  • ·        Great Horned Owls (GHOWs)

Outside of surveys:
  • ·        Gray Jays

Domestic Life:
  • ·        Humans
  • ·        Dogs

Noises:
  • ·        Wind
  • ·        Cars on roads


Survey Map:












Blue diamonds = survey points

Surveyors:
Phillip Andrews, Simon Andrews

GHOWs detected at points:
grayGPS- 469, 505: orangeGPS- 582, 605, 606, 607, 608, 621, 623/24, 626.

Cited:
BLM. 2018. https://www.blm.gov/or/plans/surveyandmanage/protocols/owl.php

Friday, September 7, 2018

Making a Map- Using Machine Learning



This page shows a workflow of modeling species distributions using machine learning data-analyses such as classification and regression trees (CART [Breiman 1984]). This is an example from an in-progress paper on Madagascar's biodiversity

Workflow borrowed from report draft, "Predicting species distributions from open-access data of Madagascar," Andrews, P., Huettmann, F., Spangler, M. 2018.

For more on machine learning, check out these YouTube videos:

General

In-depth



GGO Map- Model Predictors

A wide range of predictor types will be used in the machine learning process. Each of these predictors, with the exception for the temporal measurement of time of fire, are all defined by their spatial extents. Some of the predictors that will be used are:

  • Precipitation
  • Vegetation type
  • Location of water bodies
  • Wildlife ranges (by species)
  • Distance to roads
  • Climate classification
  • Distance to plane runways
  • Temperature

      Please note that these predictors are not necessarily a direct function of GGOW occurrence. It may be difficult to relate human population density, for example, with high GGOW occurrence. But correlation does not imply causation.
      One assumption used in the model is that ground cover (e.g. vegetation, urbanized area) outside of fire zones will not have changed dramatically within 5 years. This will allow for analysis of relatively constant ground cover.

Big Players in Great Gray Owl Literature/ Essential Readings


Distribution, abundance, and habitat of great gray owls in Southcentral Oregon
Bryan, T., E.D. Forsman. 1987. The Murrelet 68(2):45-49.


Diet and optimal foraging of great gray owls
Bull, E.L., M. Henjum, R. Rohweder. 1989. The Journal of Wildlife Management 53(1):47-50.

The great grey owl strix nebulosa- a bird of the northern taiga
Hilden, O., P. Helo. 1981.  Ornis Fennica 58:159-166.

Effect of cyclic and declining food supply on great grey owls in boreal Sweden
Hipkiss, T., O. Stefansson, B. Hornfeldt. 2008.  NRC research press web. Canadian Journal of Zoology. 86:1426-1431.

The great gray owl: phantom of the northern forest
Nero, R.W.. 1980. Smithsonian Institution Press. Washington, D.C.. 167 pp.

Status, distribution and ecology of the great gray owl (Strix nebulosa) in California [thesis]
Winter, J. 1986. San Francisco State University. 121pp.

Tuesday, September 4, 2018

What Owls Are Found In Alaska?

Nine species of owls call Alaska home for at least some part of the year.

1. Barred Owl (Strix varia)
(according to ADF&G)


2. Boreal Owl (Aegolius funereus)
 


3. Great Gray Owl (Strix nebulosa)
 


 4
. Great Horned Owl (Bubo virginianis)
 


5. Northern Hawk Owl (Surnia ulula)
 


6. Northern Pygmy Owl (Glaucidium gnoma)
  
Map from Birds of North America (https://birdsna.org/Species-Account/bna/species/nopowl/introduction)


7. Northern Saw-whet Owl (Aegolius acadicus)
 



8. Short Eared Owl (Asio flammeus)
 


9. Snowy Owl (Bubo scandiacus)
 


10. Western Screech Owl (Megascops kennicottii)
 

Map color legend


Maps and images from Audubon.org