Final TMTC Report - 1996 Parrish

pairs followed lost eggs which were not replaced. Six additional eggs were found
abandoned at the onset of observations (20 June). Assuming these six eggs represented six
additional pairs, hatching success was 0.29 chicks per pair, and fledging success was 0.53
to 0.84 fledglings per chick (depending on whether the 4 chicks remaining on the
subcolony at the end of the field season, 5 September, are presumed to have fledged or
not).

Factors Affecting Murre Demographics

Eagles

Adult mortality was affected by Bald Eagle predation; 5 kills were witnessed and 20
carcasses (including the witnessed kills) were found. These numbers are absolutely
comparable to 1994; however, kills were witnessed over more hours, making the
standardized value lower. As more days were spent on Tatoosh in 1996, the number of
carcasses found might also be relatively lower, although carcass residence time is days to
weeks (Parrish, unpub. data). For the first time, eagles were witnessed taking adult
murres from both cliff-top and crevice subcolonies. If witnessed kills are standardized by
number of observation hours, the number of days in the season during which both murres
and eagles are present throughout the day, and the number of hours over which eagles are
present per day, a maximum of 63 kills would have been made, or almost 2% of estimated
afternoon attendance (Parrish and Paine, unpub. manuscript).

Eagles also exerted an increasing indirect effect on murre reproductive success, through the
facilitation of egg predation by gulls and crows (Parrish 1995). Because eagles were
successful in attacking murres nesting in crevice subcolonies, these areas were subject to
much higher levels of eagle-induced evacuation, which ultimately resulted in severe
depression of reproductive success (Table 3). In previous years, the indirect effect of
eagles has been contained to cliff-top subcolonies (Parrish 1995, 1996). However, in
1996 an apparent reversal occurred - eagle influences, as assessed by reproductive success,
were stronger in the crevice subcolonies, even though eagle kills were also witnessed on
both monitored cliff-top subcolonies. It is possible that cliff-top nesters are becoming more
habituated to the presence of eagles (Parrish, unpub. data), while crevice nesters are
experiencing a "new" threat. Regardless, it is apparent that nesting habitat quality, relative
to adult security, is more a function of the behavioral repertoire of the predators than to any
physical quality of the habitat itself. Future trends in eagle-murre interactions are hard to
predict, as the number of eagles visiting Tatoosh is not a linear function of their presence

15


Table 2 - Average of attendance counts made from BBPT (1991-1996) during egg/chick period for
monitored crevice subcolonies.

MornX MornSD MornN Aft X Aft SD Aft N

1991 crisscross 1 24.50 8.67 3 38.50 16.26 2
crisscross 2 16.83 454 3 44.83 28.06 3
crisscross 3 27.00 1
crisscross 4 42.00 19.67 3 59.75 14.50 2
crisscross 5 110.00 8.66 3 173.33 66.82 3
tenniscourt 1 30.00 1 78.50 30.41 2
tenniscourt 2 30.00 1 50.00 1
tenniscourt 3 60.00 1 81.50 26.16 2
tenniscourt 4 10.00 1 25.00 7.07 2
TOTAL 323.33 578.42
ADJUSTED 291.73 505.21
Note: The 1991 counts were made from SB and TP NOT BBPT; pre-spill only
Adjusted totals: BBPTCC4=CC4*.5; BBPTCC5=CC5*.75; AFT=MORN*1.6

1992 crisscross | 21.20 9.36 5 31.25 5.73 8
crisscross 2 25.20 7.46 5 36.00 9.74 8
crisscross 3 15.80 9.36 5 30.25 6.86 8
crisscruss 4 10.60 3.13 5 15.88 1.81 8
crisscross 5 76.40 22.81 5 93.88 18.14 8
tenniscourt 1 26.40 12.10 5 34.88 3.40 8
tenniscourt 2 19.60 10.24 5 27.50 3.42 8
tenniscourt 3 66.40 34.26 5 90.88 10.26 8
tenniscourt 4 17.00 7.07 5 23.38 4.00 8
TOTAL 278.60 383.88

1993 crisscross 1 19.00 1 28.43 5.13 7
crisscross 2 5.00 1 30.29 11.76 7
crisscross 3 0.00 1 16.71 11.00 7
crisscross 4 8.00 1 13.43 2.99 7
crisscross 5 56.00 1 84.71 16.85 7
tenniscourt | 28.00 1 30.33 5.28 6
tenniscourt 2 14.00 1 22.50 5.17 6
tenniscourt 3 49.00 1 70.83 9.41 6
tenniscourt 4 19.00 1 21.00 2.76 6
TOTAL 198.00 318.24

1994 crisscross 1 27.13 4.64 15 29.31 5.25 16
crisscross 2 31.50 13.75 14 35.50 9.17 16
crisscross 3 21.07 8.18 15 26.69 9.67 16
crisscross 4 11.33 5.42 15 17.35 13.53 17
crisscross 5 76.47 16.17 15 85.53 12.80 15
tenniscourt 1 20.43 8.71 14 28.53 7.16 17
tenniscourt 2 12.71 8.43 14 19.53 9.68 17
tenniscourt 3 35.29 23.45 14 64,35 26.34 17
tenniscourt 4 18.77 451 13 21.25 4.80 16
TOTAL 254.70 328.05


Final TMTC Report - 1996 Parrish

List of Figures and Tables

Figure 1. Schedule of island visitation and Tatoosh Island Common Murre breeding
phenology, 1996.

Figure 2. Attendance of Tatoosh Island Common Murres on nine index crevice subcolonies
as a function of time of day, 1996.

Figure 3. Daily attendance of Tatoosh Island Common Murres on nine index crevice
subcolonies, 1996.

Figure 4. Schematic representation of blind placement on a cliff-top subcolony.

Table 1. Estimated annual afternoon attendance of Tatoosh Island Common Murres, 1991-
1996.

Table 2. Average annual attendance counts from BBPT of index crevice subcolonies, 1991-
1996.

Table 3. Reproductive output of Tatoosh Island Common Murres in crevice (1992-1996)
and cliff-top (1996) index subcolonies.

Table 4. Aircraft type and response of Tatoosh Island Common Murres, 1996.

iv


Final TMTC Report - 1996 Parrish

on the mainland, not all eagles visiting Tatoosh attack murres, and murre response appears
to change over time (Parrish and Paine, unpub. manuscript).

Table 4 - Aircraft disturbance of breeding Common Murres on Tatoosh Island. Of 31
recorded incidents in which aircraft flew over the island (9 helicopters; 21 planes, | jet), 10
provoked an alarm response.

Aircraft Type Height* Duration of Stay** __Murre Response

jet high short headbob

plane unk unk headbob

plane unk unk move to edge
helicopter low long move to edge

plane low short partial evacuation

plane low short partial evacuation
helicopter low long partial evacuation
helicopter low long partial evacuation
helicopter low short evacuation, egg loss

plane low long evacuation, chicks trampled

*Height estimated relative to the OCNMS 2,000 foot ceiling
** Duration arbitrarily divided into less than two minutes (short) or greater (long).

Aircraft

Murres were also affected by the presence of aircraft. A total of 31 aircraft were recorded
flying over the island during the 1996 season (Table 4). This number should be regarded
as a minimum because observers did not always record aircraft presence, and observers
were only on the island a portion of the nesting season. On many days no aircraft were
recorded; however, on several days multiple aircraft were reported (13 days with one event;
2 days with two events; 4 days with 3 or more events). A summary report of overflights
suspected to be beneath the 2000 foot ceiling and/or disturbing the birds regardless of
height was provided to the Olympic Coast National Marine Sanctuary (OCNMS) office in
Port Angeles. Distress responses, including headbobbing, movement towards cliff/crevice
edge, and evacuation, were more likely to occur earlier in the nesting season (see also
Parrish 1995) and among nonbreeders (or failed breeders during 1996) throughout the
season. Low-flying aircraft elicited a higher level of response than high-flying ones (Table
4). Helicopters elicited a higher level of response than planes (44% of all helicopters
caused at least movement to edge while only 19% of all planes did so). This pattern of
response is not new. Parrish (1996a) reported temporary evacuation in response to aircraft
overflight. Mehlum and Bakken (1994) reporting on two helicopter disturbance


Final TMTC Report - 1996 Parrish

Citations

Birkhead, T. R. 1977. The effect of habitat and density on breeding success in the
Common Guillemot (Uria aalge). J. Anim. Ecol. 46:751-764.

Mehlum, F. and Bakken, V. 1994. Seabirds in Svalbard (Norway): status, recent changes
and management. Birdlife Conservation Series (1994) 1:155-171.

Paine, R. T., Wootton, J. T., and Boersma, P. D. 1990. Direct and indirect effects of
Peregrine Falcon predation on seabird abundance. Auk 107:1-9.

Parrish, J. K. 1995. The influence of group size and habitat type on reproductive success
in Common Murres (Uria aalge). Auk 112:390-401.

Parrish, J. K. 1996a. Continued monitoring of Common Murres on Tatoosh Island,
Unpublished Final Report to the Tenyo Maru Trustees Council, 1995.

Parrish, J. K. 1996b. Seabird-preybase interaction, Final Report to the Tenyo Maru
Trustees Council, 1995.

Parrish, J. K., and Paine, R. T. 1996. Ecological interactions and habitat modification in
nesting Common Murres, Uria aalge. Bird Conserv. Internat. 6:261-269.

Wilson, U. W. 1991. Responses of three seabird species to El Nifio events and other warm
water episodes on theWashington Coast, 1979-1990. Condor 93:853-858.

19


Table 3 - Tatoosh Island Common Murre reproductive output in crevice subcolonies (1992-
1996) as monitored from BBPT and cliff-top subcolonies (1996) as monitored from blinds.
Known pairs are defined as all pairs (assessed by location) which did or were suspected to
have eggs. Known lost eggs were either observed abandoned, stolen, smashed, or failing
to hatch. Both measures are minimum estimates of pairs and lost eggs, respectively.
Fledglings are defined as chicks known to have fledged or, in cases where observers were
not present during fledging, chicks greater than 15 days old (crevices - early years).

1992 1993 1994 1995 1996

cci1

Attendance (aft) 31 28 29 38 39

Known Pairs 15 ll 22 18 19

Known Lost Eggs 2 1 1 I 10

Chicks > 15D ll 7 20 17 2*

Fledglings/Pair 0.73 0.64 0.91 0.94 0.11

* In 1996, 3 chicks were hatched on CC1; however, by the last day of the field season, 17 September, one
chick aged less than 15 days still remained.
CC2

Attendance (aft) 36 30 35 54 59
Known Pairs 17 9 21 15 18
Known Lost Eggs 2 4 2 12 17
Chicks > 15D 16 2 18 ll 0
Fledglings/Pair 0.94 0.22 0.86 0.73 0.0
cc3

Attendance (aft) 30 17 27 57 60
Known Pairs ll 2 7 20 24
Known Lost Eggs 0 2 6 3 15
Chicks > 15D 7 0 1 17 0
Fledglings/Pair 0.64 0.0 0.14 0.85 0.0
cc4

Attendance (aft) 13 17 21 21
Known Pairs 6 7 7 10
Known Lost Eggs 1 0 0 10
Chicks > 15D 3 6 7 0
Fledglings/Pair 0.50 0.86 1.00 0.0
MCT-EXT

Known Pairs 65
Eggs Seen 64
Known Lost Eggs 22
Chicks 42
Fledgers (known;suspécted) 35:6
Fledglings/Pair 0.54-0.63
PetCol

Known Pairs 39
Eggs Seen 45*
Known Lost Eggs 26
Chicks 13
Fledgers (known;suspected) TA
Fledglings/Pair 0.18-0.28

* Six abandoned eggs were present on the first day of observations. They are not included in the
calculations of fledglings per pair (i.e. as extra pairs).


Final TMTC Report - 1996 Parrish

eding Repr tive Suc
The timing of breeding was assessed by daily checks for the presence of eggs and chicks
on four index crevice subcolonies (CC1-4) and one index cliff-top subcolony (MCT-EXT).
One additional cliff-top subcolony, PetCol, was monitored for reproductive success. Both
cliff-top subcolonies were monitored with the use of plywood blinds fitted with one-way
mirrored glass. Blinds resembled bay windows jutting from existing vegetation
(salmonberry, Rubus spectabilis) out into the area utilized by the murres (Figure 4).
Breeding murres nested against all windows and regularly interacted with their images.
Once eggs had been laid, pairs closest to the mirrors were the first to remain on their eggs
during disturbances causing the majority of the pairs to evacuate. Although observer
presence was known to the murres (based on visual fixation on the plywood wall during
observer approach), no evacuations or even movement away from the blind occurred when
observers were present, including entering and leaving the blind. Other than occasional
headbobbing early in the nesting season before the majority of eggs had been laid, the
murres showed no overt signs of distress at observer presence. Therefore, it is possible
that the presence of the.blinds affected reproductive success, albeit positively.

S

f Cliff edge

Extent of breeding murres

Figure 4. Schematic drawing of blind
placement on the MCT-EXT subcolony.
Blind is made of plywood sheets hinged
together and placed in an arc at the end
of a path cut through live salmonberry
to the edge of known murre nesting
area. A one-way, mirrored glass is set
into the central plywood panel. A tarp

NN (not shown) was used to darken the
NN, blind and prevent patrolling gulls and
AAs Yee crows from discovering observers, which

SSSSSSS PSPSPS PAIS SSS SSS LIAS prompted alarm cries. The path was
ORANG RRR RRR fenced to prevent murres and gulls from
POPPPPP ARS PRIS entering through the salmonberry.
NAAR RRNA When not in use, the window was covered
NS, ebry.. to prevent distress should a bird enter
ROO ARREARS the blind (i.e. a murre in the blind would
AAAI IN see other murres but not be able to reach

SKE them).

At the beginning of the season, likely pairs within a plot defined by geographically distinct
boundaries (crevice subcolonies - entire crevice visible from BBPT; cliff-top subcolonies -


Final TMTC Report - 1996 Parrish

record of hours spent was kept in these situations, although all data was recorded as a
specific function of when (both date and time of day) it was collected.

Laying ooo Hatching ox Fledging —>
CC1-4 — — o(1)

MCT-EXT | + — — |
| | — 1

f—T l
|
|
|

|

|
Piel |
Jensen
Parrish I
|

150 160 170 180 190 200 21

|
|
|
|
|
|
|

lel

|
|
|
|
|
|
|
J
0

220 230 240 250 260 270

June July August September

Figure 1. Days spent on Tatoosh Island during the 1996 field season, and Common Murre breeding phenology as

assessed during those trips. Top panel is a box and whiske: olot of breeding phenology for the index crevice subcolonies,
CC1-4, and the index cliff-top subcolony, MCT-EXT. Vertical bars are means, horizontal bars are range, and boxes are
standard deviation. Numbers in () following fledging ranges indicate how many chicks remained on the subcolonies on

the last day of the last trip in which chicks were seen. Dashed lines indicate probable range of laying, based on extrapolation
of incubation time or evidence of egg presence (see text for details).

Attendance

Subcolony attendance was assessed for all locations housing breeding or roosting murres,
such that an annual attendance estimate could be produced. Attendance was defined as the
number of murres on the subcolony (direct count), after eggs had been laid but before
chicks began to fledge.

Nine index subcolonies (CC1-5, TC1-4) were counted repeatedly from the BBPT location
throughout the season to assess patterns of attendance as a function of time of day and
phenology. (It should be noted that several of these subcolonies, specifically CC4 and 5,
are only partially visible from BBPT, thus the BBPT attendance index counts do not
represent the total number of murres in these locations; see differences in attendance values
between Tables 1 and 2). Annual comparisons between the index subcolonies are made in
the afternoon, defined in 1996 as the period from 1400H on (Figure 2). Morning data
points which fell well below the average (see 0900H and 1000H on Figure 2) were deleted
from the analysis due to the high probability that these data had been collected following an
eagle-induced temporary evacuation (Parrish unpub. data) and so do not represent true
attendance. Differences in attendance as a function of time of day on the index subcolonies
were used to standardize counts of other subcolonies which could only be made at specific


Final TMTC Report - 1996 Parrish

Introduction

In 1996, data collection on Common Murre, Uria aalge, attendance and reproductive
success on Tatoosh Island continued as a pilot project of the Tenyo Maru Trustees Council.
Data collection was specific to murre demographics in an attempt to identify: 1.) whether
this colony is increasing, decreasing, or stable in size, 2.) whether this colony continues to
be reproductively active and to what degree habitat type affects reproductive success, and
3.) identification of some of the factors likely to affect population demography, specifically
adult mortality and reproductive success. In the past, this colony has been affected by the
increasing presence of Bald Eagles, Halieetus leucocephalus, and their indirect effects on
reproductive success. This colony was also the closest murre colony to the site of the
Tenyo Maru oil spill of 1991, and it is likely that some proportion of the murre carcasses
recovered after this event were from the Tatoosh population. This report documents the
data collected during the 1996 field season, provides an analysis of the patterns of murre
demography relative to previous years, and summarizes the potential for restoration
activities on the Tatoosh population.

Methods

Data documenting murre attendance, phenology, and breeding success were collected on
the Tatoosh Island Common Murre population during the period spanning 12 June through
17 September. In total 51 calendar days and 96 man-days were spent on the island (Figure
1). Data on monitored subcolonies were collected from two principal locations. Burning
Barrel Point (BBPT) is a promontory which affords a simultaneous view of eleven spatially
distinct crevice subcolonies (CC1-5, TC1-4, WBMCT). In previous years, this location
also afforded a view of the MCT (Main Cliff-top), a cliff-top subcolony which was
abandoned in 1996. Observations from BBPT ranged in time from 0SOOH to 2200H, ina
minimum of 1/2hr blocks evenly spaced throughout the day (approximately 121 hrs in
total). To collect equivalent data on cliff-top subcolonies, two plywood and one-way glass
blinds were constructed on MCT-EXT (Main Cliff-top extension), a new subcolony
situated between MCT and TPCT2 (Toad Point Cliff-top 2), and PetCol (Petrified
subcolony). Because the PetCol was used as an experimental subcolony, data collected on
the MCT-EXT plot were used to monitor cliff-top reproductive success, although PetCol
data are also reported here. Observations ranged in time from 0530H to 2200H, in a
minimum of 1/2 hr blocks evenly spaced throughout the day (approximately 160 hrs on
MCT-EXT). Additional data were collected on attendance, chick presence, and adult
mortality from a variety of locations around the island, as well as from boats. No specific


Final TMTC Report - 1996 Parrish

Early egg loss was also considerable on this subcolony (17 of 38 eggs laid between 14 and
23 June were lost). Eggs began to remain on this subcolony by 14 June, and by 17 June
the majority of laid eggs were safe. Laying continued through approximately 9 July (based
on hindcasts from known age eggs); the last observed laying was 2 July (Figure 1). Mean
lay date for known-age eggs was 18 June (Figure 1), and the incubation period was 32.2 +
0.9 days (N=17). At least 6 eggs were relaid (we could not tell whether any of the eggs
laid in the latter part of June were relays of eggs lost before our first day of observation), of
which 5 produced fledglings. Three lost eggs were replaced in space by a second pair
(based on egg coloration differences), perhaps indicating that this new subcolony was
subject to some amount of intraspecific competition for limited (quality?) nesting sites.

Hatching began on 17 July and continued through 17 August (Figure 1), with a mean hatch
date of 24 July for known-age chicks (Figure 1). Hatching was not; however, unimodal.
The first peak in hatching occurred on 19-20 July (11 chicks out of 18 produced between
17 and 22 July), with a second peak occurring in the first week in August (13 chicks out of
22 produced between 27 July and 12 August). Two additional chicks were born on 17
August. Including known relays, hatching success was 0.66 chicks per egg (relay
hatching = 0.83 chicks per egg for 6 eggs). Fledging began on 10 August and ran through
the end of the last trip during which chicks were present: there were 6 chicks all in good
condition remaining on the plot on 6 September. Average chick age at fledging was 25.2 +
1.6 days (N = 17). Mean observed fledging date was 17 August (Figure 1); however, this
distribution was apparently trimodal. Sixteen chicks fledged between 10 and 16 August
(peak 13-15 August); eighteen chicks fledged between 18 August and 1 September (peak
28-30 August); seven chicks presumably fledged between 4 September and before 16
September. By 6 September, all 6 remaining chicks were 20 days or greater (mean
minimum age = 23.8 + 3.2 days). Based on the average fledging age, it is likely that these
chicks left within the next few days. The single chick which died was actually of fledging
age, but seemed to have been abandoned by its parents (Parrish pers. obs.).

Reproductive success on other cliff-top subcolonies was variable. Pole Island, now the
largest cliff-top subcolony on Tatoosh (1284 in attendance, Table 1), failed to produce any
chicks on the attendance subplot in 1996. As the general attendance pattern on this
subcolony was even across the entire area (i.e. not just specific to the subplot counted) and
total evacuations were observed through late July, by which time laying had ceased in all
index subcolonies, it is unlikely that any fledglings were produced from Pole Island. The
PetCol was reproductively active, although egg loss was high (Table 3). Twenty-six of 39

14


Final TMTC Report - 1996 Parrish

sets of BBPT counts, arrayed across time of day, were made with both types of optics. No
significant differences were found, so counts were considered equivalent regardless of
optics used. In 1996, three observers collected attendance data: Julia Parrish, Karen
Jensen, and Jennifer Piel. To insure all counts were equivalent, Piel and Jensen were
required to count in my presence and attendance data were compared until values were
within 10%. Periodic checks were made throughout the season to insure that all observers
remained within a 10% margin of error. Several crevice subcolonies were most reliably
counted from a boat (RR-U, RR-L, TP 1-3). In these cases, photographs were used to
ground truth counts. Cliff-top subcolonies were almost always impossible to count either
repeatedly and/or in total, without major disturbance to the birds. For Pole Island (PI),
approximately 25% of the subcolony was regularly counted from a remote location and
multiplied by four to generate the annual estimate. For TPCT1, only the exterior murres
visible from below and/or from a boat on the water were counted, even though the
subcolony probably contained many more birds. The preceding methods did not differ
from previous years. For MCT-EXT and the PetCol, all birds visible from the blinds were
counted and used to estimate attendance. In the latter two cases, these ¢ stimates probably
accounted for the vast majority of the birds (Parrish, pers. obs.) and did differ from
previous years, as blinds allowing observers to “enter” the colony had never been used.

600 +
38 ee © Morning (0500-1300)
§ 500+ ge 3 e Afternoon (1400-2100)
& e
os 3 eo,
2240+ ogy ° 23, ce .
a5 oe ol § 8 °
- EG) $3 8 %° © om -
§ ¥ 300 + ° %° o&, .
3 ° oS o Fo tp 8
<5 200 4 ° 2 +
g % 8
2 100 + °,
° 0
6 16 26 6 16 26 5 15 25 4 14
June July August September
Date

Figure 3. Daily attendance of Tatoosh Island Common Murres on nine index crevice
subcolonies (CC1-5; TC1-4) during the morning (open circles) and afternoon (filled
circles) hours, 1996. See text for time of day definitions. By mid to late July attendance
became unstable, such that only data collected in June were used to determine estimated
annual island attendance (i.e. Tables 1 and 2).



Final TMTC Report - 1996

Parrish

Attendance and Reproductive Success of Tatoosh Island Common Murres

Final Report 1996
November 1997

Julia K. Parrish

Zoology Department, Box 351800
University of Washington

Seattle, .VA 98195

jparrish @u.washington.edu

prepared for the Tenyo Maru Trustees Council
Principal Investigator: Julia K. Parrish
Technician: Karen Jensen
Student Employees: Jennifer Piel
Laura South-Oryshchyn
Suzanne Romaine
Student Volunteers: Anne Edwards


Final TMTC Report - 1996 Parrish

attendance, the crevice index subcolonies rose by 8% (from 446 to 484 birds) and the
overall colony figure rose 6% (from 3270 to 3467), relative to 1995 counts, respectively.
In total, 27 subcolonies increased in size from the previous year, while only 7 declined,
and one remained stable (Sign test (H,: p = .5), Coosaas = 10, P < 0.005; Table 1). The
majority of the increases were moderate (i.e. ones to tens of birds). Annual estimates of
afternoon attendance have been relatively stable since 1993, fluctuating between
approximately 3300 (1995) and 3700 (1994) birds. Although these estimates have not
reached those of earlier years (approximately 3900-4200 birds prior to 1993), the colony
does not appear to be in a pattern of constant decline.

Several colonization trends begun earlier in the decade continued. The total number of
discrete breeding areas continued to increase. Four new crevice subcolonies were “born”
in 1996 (Table 1), most adjacent to existing crevices (e.g. RCC-L immediately below RCC;
Table 1). However, WBMCT (Way Below Main Cliff-Top) is on a previously unoccupied
cliff-face. Cliff-top subcolonies continued to fluctuate, exemplified by the total
abandonment of the MCT, which had been declining for several years (Table 1), after a
meteoric rise in the 1980's (Parrish & Paine 1996). A new breeding cliff-top subcolony
was “born” this year, for the first time since observations began in 1991. MCT-EXT is a
smaller area located in salmonberry cover immediately between the former MCT and
TPCT2.

Total attendance in crevice subcolonies continued to rise for the fourth year, increasing
19% over 1995 to 1614 birds (Table 1). Index crevice subcolony counts showed an
identical pattern: afternoon averages have been consistently higher each year since 1993,
and are significantly higher than 1995 (two-tailed T-test of means, T = -2.585, V = 19, P<
0.02; Table 2). The 1996 afternoon count, 484 birds, is only 26 birds lower than the
original 1991 pre-spill estimates (Table 2), a statistically indistinguishable difference.
Cliff-top attendance declined slightly, a fairly steady trend since counts began in 1991. As
a result of these two opposing trends, the ratio of crevice to cliff-top attendance shifted
closer to equality (47% crevice:53% cliff-top; Table 1).


Final TMTC Report - 1996 Parrish

plot in view of windows defined by stakes) were identified by behavior and/or the presence
of an egg. Eggs were identified by location, color, and spotting pattern. When possible,
the fate of individual eggs and chicks were followed. This was easier on the clifftop
subcolonies where blind proximity allowed observers to record the presence of very young
chicks (e.g., hatching day). In crevice subcolonies, young chicks were harder to see and
may have been missed. Therefore, for these nesting areas, chicks are reported as chicks
greater than 15 days of age to allow for the possibility of missed mortality of very young
chicks. Drawings were made of the plumage pattem of each chick on the last day of each
trip, such that subsequent identifications could be made even if chicks wandered. In
practice, all subsequent identifications were confirmed by watching the parents, who
remained faithful to specific locations, feed the chick. Fledging was defined either by
watching the chick leave (known fledging date), or by inferring its departure (for chicks
older than 15D), although only known events (e.g. witnessed laying, hatching, and
fledging) were used to assess breeding phenology statistics. Incubation length and average
chick age to fledging were calculated for eggs/chicks of known age. In addition, chick
presence was noted on all other subcolonies. No chicks or adults were banded.

F ffecting Murre

Adult mortality was assessed by observing the number of murres successfully attacked by
predators (Bald Eagles) as a function of hours of observation over the period eagles were
present on the island. In addition, daily walks of the beach and accessible eagle perches
were conducted to look for murre carcasses. All carcasses were marked with fingernail
polish (one color for each calendar month) and left in place to assess residence time and
scavenging. The number of murre eggs found outside of the subcolonies (usually broken
below crevices and cliff-tops) or removed from subcolonies by predators was also
opportunistically assessed as a surrogate measure of mortality pressure on young-of-the-
year. Observations on murre response to aircraft were made opportunistically.

Results and Discussion

Attendance

The 1996 season was marked by extremely low reproductive success which translated into
early departure of some of the breeding population and increasing variance in general
attendance of the remaining population after the loss of the majority of the eggs. Index
counts of the crevice subcolonies (CC1-5, TC1-4) began to decline in mid-July (Figure 3;
majority egg loss by July 18), although birds were still present in September. However, if
only June counts (i.e., before substantial egg loss) are used to estimate annual afternoon


Final TMTC Report - 1996 Parrish

times of day due to tidally-mediated inaccessibility. In 1996, afternoon index subcolony
counts were 1.35 higher than the morning counts; thus, all attendance data collected on
other subcolonies before 1400H were standardized to “afternoon” estimates with the use of
this correction factor to produce the annual attendance estimates reported in Table 1.

600 4 l
|
|
| . °
500 4 |. : .
¢ e e
i] tos
I t
4 |
= Loe g8 |
3 8 |
= 8 oe ee
< e oe |
. |
300 4 |
° |
° |
|
hd |
200 +r T T T T T T r 1
500 700 900 1100 1300 1500 1700 1900 2100
Time of Day

Figure 2. The pattern of diurnal variation in attendance in common Murre crevice subcolonies
(CC1-5+TC1-4), as counted from the BBPT location, between 12 June and 3 July 1996. After
this period, subcolony attendance became unstable due to egg loss-induced abandonment of adults.
The dashed line indicates the split between morning and afternoon classification in this report.

Attendance patterns on the index subcolonies as a function of phenology were used to
indicate when attendance was unstable and thus not a valid representation of annual
attendance. In 1996, index subcolonies became unstable by mid-July (Figure 3), indicating
that data collected during June only were suitable for annual attendance estimate
assessments. Therefore, although data were collected throughout the breeding season,
both the annual attendance estimate (i.e. Table 1) and the index attendance averages (i.e.
Table 2) are constrained to data collected prior to 16 July.

Attendance data were almost always direct counts. Occasionally, a subcolony could not be
counted from a single location (e.g. CC4, CCS). In these cases, counts were made from
multiple locations and degree of spatial overlap was estimated by mapping physical features
of the surrounding rock. The annual estimate is an amalgam of these site-specific values.
Counts made from the BBPT location were usually made with a spotting scope, while
counts from other locations were made with binoculars. To insure equivalency, several


Final TMTC Report - 1996 Parrish

highly productive area (Parrish 1996b and references therein) which may account for the
relatively high diversity of nesting seabirds (Paine et. al. 1990), as well as the persistence
of murres when other Washington colonies appear to have undergone massive declines
(Wilson 1991). Known threats to the Tatoosh colony include marine pollution, specifically
oil, disturbance by aircraft, and predation and associated egg-predator facilitation by Bald
Eagles. Suspected threats include fishery by-catch mortality. The Tatoosh colony is also
responsive to changes in ocean temperature and presumably the associated changes in food
supply. The extent, or even existence, of ocean-mediated change in murre food supplies
(e.g. schooling planktivores) is unknown for the Washington and Oregon coasts.

In conjunction with coastwide censuses, continued monitoring of this colony, to insure that
adequate measures are being taken to safeguard existing murres, would seem to be
paramount. Demographic data would also serve as an indicator of local to regional coastal
productivity relative to seabirds as well as a potential early warning for Puget Sound gillnet
fisheries (Parrish and Melvin, unpub. data). Additional data on forage fish species and
delivery rate could provide baseline data on food availability (Parrish, unpub. data). These
data, even locally collected, would seem to be necessary groundwork for any more
extensive program of forage fish restoration. The Tatoosh colony has also been the site of
several small-scale restoration experiments (Parrish and Paine 1996, Parrish unpub. data)
and could continue to be used in this capacity. Finally, population levels of Bald Eagles
and Glaucous-winged Gulls, should be monitored. Attempts should be made to minimize
the positive effects humans can have on these predators (i.e. access to additional sources of
food as a consequence of human actions).

On a regional scale, mitigation of known, particularly anthropogenic, threats to murre
survival and reproductive success should be addressed, when possible. Direct disturbance
by humans could be minimized, perhaps incrementing reproductive success and possibly
facilitating additional colonization. Public education programs designed to inform coastal
user groups about human impact on seabirds might be directed at boaters, aircraft pilots,
and ecotourist organizations to start. Because many seabird species, including murres, use
inland waters during the non-breeding season (e.g. Puget Sound), education programs
should cover summering as well as wintering grounds. Fishery by-catch solutions, already
under consideration in Puget Sound, might be extended to other fishery regions. Finally,
factors responsible for the decline of Washington's southern colonies need to be identified,
if possible, in order to determine the most plausible course of potential restoration efforts
on these colonies.

18


Final TMTC Report - 1996 Parrish

Table of Contents

Cover Page i
Acknowledgments ii
Table of Contents iii
List of Figures and Tables iv
Introduction 1
Methods 1
Attendance 2
Breeding Phenology and Reproductive Success 5
Factors Affecting Murre Demographics 6
Results and Discussion 6
Attendance 6
Breeding Phenology and Reproductive Success ai
Factors Affecting Murre Demographics 15
Eagles 15
Aircraft 16

Oil 17

Food Availability 17
Conclusions 17
Citations 19


Table 2 - Average of attendance counts made from BBPT (1991-1996) during egg/chick period for
monitored crevice subcolonies.

1995 crisscross 1 36.57 4.72 7 37.82 3.84 lL
crisscross 2 41.43 8.62 7 53.82 12.29 11
crisscross 3 49.71 11.79 7 57.09 8.07 ll
crisscross 4 19.57 5.09 7 21.00 5.51 ll
crisscross 5 100.52 13.61 7 114.00 14.81 11
tenniscourt 1 35.57 6.21 7 40.09 3.94 11
tenniscourt 2 20.86 3.98 7 25.73 3.44 11
tenniscourt 3 72.00 12.68 7 77.00 8.45 11
tenniscourt 4 15.86 2.97 7 19.45 5.57 ie
TOTAL 392.10 446.00

1996 crisscross 1 31.00 3.49 23 39.36 4.84 14
crisscross 2 37.52 3.61 23 58.93 9.03 14
crisscross 3 38.74 7.94 23 59.57 6.41 14
crisscross 4 14.68 2.55 22 21.08 4.25 12
crisscross 5 95.50 749 22 119.90 8.69 13
tenniscourt 1 31.45 4.07 22 39.92 4.80 13
tenniscourt 2 20.27 3.95 22 29.92 4.80 13
tenniscourt 3 72.91 8.85 22 95.31 8.12 13
tenniscourt 4 14.82 3.14 22 20.08 2.14 13
TOTAL 356.89 484.07

Note: In 1996, the counts for CC1, 4, and 5 are lower than in Table 1 because neither
crevice was entirely visible from BBPT.

Note: Attendance data for this Table from 12 June through 3 July 1996 only.

Note: Low counts (see Figure 1) were removed before calculating statistics.

10


Final TMTC Report - 1996 Parrish

Of 17 eggs on CC1 and CC2 where we were able to observe both lay and loss date, mean
and standard deviation of residence time was only 6.6 + 5.4 days. On the index crevice
subcolonies, eggs were lost on every day of observation, through 18 July, after which
occasional remaining eggs were taken by gulls. This early, intense period of egg loss
resulted in the lowest reproductive success in the crevice subcolonies of any year since
observations began (1992) and was the reason that attendance began to fall off in July. Of
71 pairs followed on CC1-4 (the highest number of pairs since observations began), only
three produced chicks, all on CC1 (Table 3). Because egg loss was so high, accurate
measures of breeding phenology were impossible to determine for the crevice subcolonies.
Therefore, laying, hatching, and fledging periods are represented by bars encompassing
known events, and do not indicate central tendency (Figure 1).

Based on the three chicks produced in CC1, breeding phenology in the crevices was later
than that of the cliff-top index subcolony, a reversal of the trend in earlier years (Parrish
1996a). Chick hatching began at the end of August, two chicks fledged on 16 September
(Figure 1), and a single chick (aged 13 days) was still present on CC1 on 17 September
(the last known murres on the island). This is later than any known fledging since 1991
(Parrish 1996a). It should be noted that several other crevice subcolonies which are not
specifically monitored for reproductive success, did produce chicks which eventually
fledged. Although no record of individual chicks were kept, all chicks seen were noted so
that reproductive success could be assessed as a 0/1 variable by subcolony (Table 1).

Ironically, the index cliff-top subcolony, MCT-EXT, had relatively high reproductive
success, 0.54 to 0.63 chicks per pair (depending on whether the 6 chicks remaining on the
plot are counted as having fledged; Table 3), a statistic approaching crevice reproductive
success in earlier years, and significantly higher than reproductive success on the former
MCT (i.e. 0.0 chicks per pair; Parrish 1996a). It should be noted that measurements of
reproductive success on this subcolony are more accurate than any collected on the Tatoosh
population to date, as observers were extremely close to the plot (i.e. less than 1 meter
away) and were able to accurately gauge the number of pairs as well as record the presence
of all eggs and chicks daily. Therefore, the chicks per pair figure is probably lower than
comparable crevice subcolony numbers from previous years, as the latter values minimized
the number of "eggless” pairs.

12


Final TMTC Report - 1996 Parrish

Acknowledgments

The author wishes to thank the Makah Tribal Nation and the U. S. Coast Guard for
continued access to Tatoosh Island. Tom Good provided information on carcass recoveries
in southern Washington. Ed Melvin provided information on gillnet modification
experiments in Puget Sound as well as information on the number and species of carcasses
being recovered by U. S. Fish and Wildlife personnel in Oregon (Roy Lowe). Bill
Sydeman provided information on the status of Common Murre nesting on the Farallon
Islands. Chris Thompson provided information on murre chick sightings along the
Washington coast, and was gracious enough to alter his survey schedule to accomodate our
use of the R/V Tatoosh. Dr. Robert T. Paine provided needed field and laboratory
assistance, logistics, and accomodations. Additional logistical support was provided by the
Olympic Coast National Marine Sanctuary (OCNMS) in the form of vessel, R/V Tatoosh,
support and trailer accomodations. Funding for this study was provided by the Tenyo
Maru Trustees Council to the University of Washington. Additional financial support was
provided by Washington Sea Grant and Olympic Coast National Marine Sanctuary grants
to JKP and an NSF grant to RTP.


(11) Specifics of aircraft disturbance. I report aircraft disturbance, among a variety of other
disturbance factors, because it is something the Trustees, as members of State and Federal
stewardship agencies, may be able to address. However, I believe it is inappropriate to lay
blame at the feet of specific individuals in a report of this nature. As per my agreement
with the Olympic Coast National Marine Sanctuary, I send a more detailed recording of all
aircraft disturbance witnessed by me or my staff during the season. On occasion, I have
also sent copies to the Makah and the U. S. Fish and Wildlife Service Refuge Office in
Nisqually. If the Trustees would like this level of detail, I will provide it under separate
cover. However, I believe it is beyond the bounds of my data collection agreement with
the Trustees.



Table 1 Average estimated annual attendance (afternoon counts during the egg/chick period) - Tatoosh Island
Common Murres. a=afternoon, m=morning, Rk#=USFWS rock number, cr=crevice, ct=clifftop, n=no, y=yes,

p=probablysubcolony

Rk# Hab. 1991 1992 1993 1994 1995 1996 Chks? Comments

rainbow rock-u 035 cr 212 200 n_— |bom in 1995
rainbow rock-1 035 cr | 50 63 24 35 38 15 P
boom 021 ct | -50 0 0 0 0 0 died in 1991

m north island 022 =socr 99 134 100 150 136 139 Pp

m |north island ridge 022 ct 22 0 0 born in 1993

m |north island 2 022. ocr 27 «(28 n {born in 1995

m |finger 022. scr 31 16 38 n {born in 1994

m |pole island 023 ct | 1300 1532 1176 1264 1108 1284] p_ |plotest. @ 25%

m |lighthouse | 0210 ocr 89 75 27 101 110 132

m |lighthouse 2 021. ocr 3 0 1 8 6 9

m |lighthouse 3 021. ocr 23 15 0 25 19 15

m |lighthouse 4 021. socr 1 25 8 6 28 «(35 n

m |lighthouse 5 021. 0socr 17 28 y _|born in 1995

m submarine 021 cr | 50 30 42 43 44° SI y

m |below submarine 021 cr s n_ jborn in 1996

m |burning barrel 021)socr 6 9 0 6 2 16 n

m |burning barrel2 021 cr 3264 n_— |borm in 1995

m |burning barrel3 021 cr 2 13 n_— |born in 1995

a jabovecrisscross 021 cr 3 6 10 n_— }bor in 1994

a {crisscross 1 021. «cr | 39 «#320 28 «©2938 52. y

a |crisscross 2 021) ocr 45 37 30 36 «(S40 59 n

a |crisscross 3 021. cr | 27) 31 #17) 27) S759 n

a/m|crisscross 4 021 cr | 60 35 34 52 50 54 Pp
a/micrisscross 5 021. cr | 173) 94 «85 «6104 141 173 y

m |r-crisscross 021. socr 15 21 10 26 36 9

m |r-crisscross lower 021 cr 21 born in 1996

m |fr-crisscross 021 «cr | 20 #19 12 22 12 35

m |fr-crisscross 3 021 ocr 15 born in 1996

a |tenniscourt 1 021. cr | 79 36 30 29 40 40 y

a |tenniscourt 2 021. cr | 50 29 23 20 = 260~=«(30 y

a |tenniscourt 3 021. scr 82 91 7 64 77 95 y

a |tenniscourt 4 021 cr} 25 23 21 21 19 20 y
moustache 021. scr 3 0 born in 1995

m |toadpoint 1 021.0 ocr 50 27 25 43 60 61 Pp

m |toadpoint 2 021 cr | 50 22 35 24 24 27 Pp

m |toadpoint 3 021.0ocr 50. 15 15 19 230 (35 1)

m |tpclifftop 1 021 ct | 48 30 26 7 15 19 partial count
tpclifftop 2 021. sect 24 46 30 4 17 0 partial count
main clifftop 021 ct | 1500 1200 1300 1200 600 0 max count

a |mct-extension 021 oct 300 y {born in 1996
below met 0210 ocr 10 0 0 born in 1994

a |waybelowmct 021 cr 31 y  |born in 1996

a_|petrified 021 _ct_| 200 200 200 260 175 250 y___ estimate
total 4214 3871 3370 3691 3270 3467
morn-aft multiplier 16 15S 12 13 1.13 1.35
crev total 1092 863 638 934 1355 1614
ct total 3122 3008 2732 2757 1915 1853
crevice % 26 #22 «190«250 4k 47



Final TMTC Report - 1996 Parrish
Because the number of murres attending crevice subcolonies is higher than it has been since
1991, and new crevice subcolonies have been “born” consistently since 1994, it appears
that the Tatoosh population may be rearranging itself. It is impossible to tell to what degree
the birth of new subcolonies may represent immigration, rather than returning first-time
breeders from the Tatoosh population. Although other studies have shown that
subcolonies may die out, this is usually a gradual phenomenon during which the abundance
(ie. absolute number) as well as density (i.e. interpair spacing) of murres declines, often
with resultant depression of reproductive success (e.g. Birkhead 1977). By comparison,
subcolony birth and death on Tatoosh is often dynamic (e.g. the birth of RR-U in 1995 and
WBMCT in 1996, both of which produced fledglings in the first year) and does not appear
to involve differences in density (e.g. the abandonment of the MCT, although it happened
over several years, never produced a fragmented set of nesters but instead a single steadily
shrinking and maximally dense group; Parrish pers. obs.). As several of the extant crevice
subcolonies have additional unused space, and there are several unused but habitable
crevices, the Tatoosh population could continue to expand, even if cliff-top subcolonies
continue to shrink.

ding Phenology and Reproductive Success
In 1996, eggs appeared on the crevice (CC1-4) and cliff-top (MCT-EXT) index
subcolonies on the morning of 13 June, the first full day of our field season. By
afternoon, all of these eggs had been lost. Thus, it is highly likely that laying had begun on
an earlier date, and that these earlier eggs had been lost as well. Additional support for this
hypothesis comes from the fact that on the afternoon of 12 June, several smashed eggs
were observed below the crevice subcolonies, and a single egg was found on the main
beach, presumably transported there by gulls or crows. In previous years, eggs have been
present in crevice subcolonies as early as 1 June (Parrish 1996a).

Egg loss was extremely heavy in 1996. A total of 239 eggs were observed cither smashed
below breeding crevices, on the main beach or island top, or being taken from breeding
areas by Glaucous-winged Gulls, Larus glaucenscens, or Northwestern Crows, Corvus
caurinus. Although this total is absolutely lower than that of 1994 (278), this comparison
is misleading as the 1994 figure contains a majority of eggs from the MCT, which was
abandoned by 1996. In 1996, the majority of smashed eggs were sighted under the
Crisscross crevice subcolonies (Parrish, pers. obs.).

1