Crevice Subcolonies - Crevice subcolony reproductive success was variable, but well
above 1996 levels (0.03 for CC1-3; Table 3). Excluding CC4 (for which accurate fledging
numbers are not available due to a probable complete set of relayings which pushed
breeding phenology into September), 67 pairs were followed. Assuming all chicks older
than 15 days successfully fledged, fledglings per pair was 0.87.

Non-monitored Subcolonies - Incidental observations of all other subcolonies visible from
an island-based locations (i.e., not TP1-4, TPCT 1-2, RR1-2) indicated that the vast
majority of these nesting areas produced chicks (Table 1). Over the 42 subcolonies
attended in 1997, chicks were definitely produced in 32, probably produced in an
additional 6, and definitely not produced in 1 (FRCC3; Table 1). Nevertheless, there were
grossly apparent differences in production rate in some locations. Pole Island and North
Island (NI) sustained eagle harassment through mid-July. Pole Island was empty through
13 June and complete evacuations were observed through 18 June; near total evacuations
were observed as late as 26 June. Beyond this date, some number of murres (greater than
50) always remained on PI when eagles flew by or landed, presumably to attack the adults.
No successful kills were witnessed. The effect of this harassment, other than a decline in
attendance, was a delay and a depression of breeding. By late July, no chicks were visible
on either PI or NI, and adults returning to PI rarely brought fish, an indirect measure of the
presence of chicks (for 15 minute watches, adults with fish/total adults returning: 26 July -
1/38; 28 July 0/70; 30 July 0/71). However, by late August, during or after peak fledging
in the monitored cliff-top subcolonies, adults were returning with fish (PI fish watch: 24
August 43/81) and young chicks (estimated age 5-8 days) were visible on both
subcolonies. I estimate that fledgling production from PI was lower than most or all other
nesting areas on Tatoosh, and was significantly lower than either the monitored cliff-top or
crevice subcolonies.

FACTORS AFFECTING MuRRE DEMOGRAPHICS
Eagles - In 1997, eagle presence on Tatoosh was markedly lower than in previous years
(Parrish unpub. data). Fewer eagles were seen either roosting on the island or flying by
regular observation locations (e.g., BBPT). Indirect evidence of lessened eagle presence is
the dramatically lower number of recovered murre carcasses with signs of raptor attack
given relatively equal effort). In 1997, only two murres were killed by eagles and an
additional two carcasses were found (total of 3 observed or inferred eagle kills). One was a
presumed raptor kill; however, the other was an intact, emaciated carcass which floated
ashore. Instead, eagles appeared to concentrate their attacks on adult Glaucous-winged


(Table 2). Note that there are slight differences in mean test values and values presented in
Table 2, due to slight variations in samples used (Table 2 - all samples; statistics - only full
counts). Afternoon counts were 24% lower in aggregate than in 1996 (1996 divided by
1997), a highly significant decline (two-sided t-test, T=10.034, df=54, p<0.001). The
daily pattern of attendance was similar to previous years but more variable (Figure 2).
Although attendance was definitely lower in the morning, there was not the clear sigmoidal

attendance curve displayed in earlier years (compare, for instance, Figure 2 from Parrish
1997).

500)

i) (2)
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8 e | 8
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2300) IS °° !
Co 6
z i °
lo
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| |
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100 | © Morning (0600-1100) ;
oy ¢ Afternoon (1200-2000) |
°
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152 162 172 182 192 202 212 222 232
June 1 July 1 August 1

Julian Day

Figure 3. Daily patterns of attendance summed over CC1-5 plus TC1-4 as counted
hourly. Data are from 11 June through 14 August 1997 and include only counts of all
relevant crevices (i.e., no missing data). Regular dashed lines indicate the period over
which attendance as a function of time of day was assessed (see Figure 2). (1) The first
day murres were observed on crevices throughout the day. (2) Fledging begins in the
crevices. (3) Fledging begins in the cliff-top subcolonies.



Islands - Point Reyes Bird Observatory) and Alaska (Middleton Island, Barren Islands,
Semidi Islands - US Fish & Wildlife Service), for metapopulation- level analyses of local,
regional, and global forces (e.g., El Nifio) affecting murre distribution and abundance.

REFERENCES

Ainley, DG, Sydeman, WJ, & Norton, J 1995. Upper trophic level predators indicate
interannual negative and positive anomalies in the California Current food web.
Mar. Ecol. Prog. Ser. 118:69-79.

Barber, RT & Chavez FP 1986. Ocean variability in relation to living resources during the
1982-83 El Nifio. Nature 319:279-285.

Boekelheide, RJ, Ainley, DG, Morrell, SH, Huber, HR, & Lewis, TJ 1990. Common
Mure. In: Seabirds of the Farallon Islands (DG Ainley & RJ Bokelheide eds.)
Stanford University Press, Stanford CA. pp:245-275.

Hodder, J & Graybill, MR 1985. Reproduction and survival of seabirds in Oregon during
the 1982-83 El Nifio. Condor 87:535-541.

Parrish, JK 1997a. Attendance and reproductive success of Tatoosh Island Common
Murres, Unpub. Final Report to the Tenyo Maru Trustees 1996.

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

Parrish, JK, Lemberg, N. & South-Oryshchyn, L 1998. The at-sea distribution of four
seabird species: Effects of colony location and nekton abundance. Fisheries
Oceanography (accepted). :

Parrish, JK, and Paine, RT 1996. Ecological interactions and habitat modification in
nesting Common Murres, Uria aalge. Bird Conserv. Internat]. 6:261-269.

Sydeman, WJ 1993. Survivorship of Common Murres on Southeast Farallon Island,
California. Ornis. Scand. 24:135-141.

Wilson, UW 1991. Responses of three seabird species to El Nifio events and other warm
water episodes on the Washington coast, 1979-1990. Condor 93:853-858.


EXECUTIVE SUMMARY

In 1997, Common Murres (Uria aalge) nested on Tatoosh Island, Washington and
successfully produced fledglings. The colony-wide attendance estimate was 3204, 8%
lower than 1996, and the lowest figure since attendance estimates started in 1991.
Multiply-counted subcolonies were also depressed in mean afternoon attendance (down
24% from 1996) a highly significant decline. The breeding season was slightly delayed
relative to the 1996 season, but was not unusually late. Phenology appeared to be
synchronized within a subcolony but not necessarily between subcolonies. For pairs
nesting on monitored cliff-top subcolonies, laying peaked between 15 and 29 June,
hatching between 17 and 30 July, and fledging between 10 and 28 August. Several
subcolonies lost eggs in late June/early July and relaid such that chicks were still hatching
in late August. Although murre numbers appeared to be lower than in previous years,
reproductive success was uniformly high in all monitored subcolonies. Fledglings per pair
ranged from 0.87 in the monitored crevice subcolonies to 0.74-0.78 in the monitored cliff-
top subcolonies. These are the highest reproductive success values recorded on the cliff-
top subcolonies since monitoring began (1992). The main factors most likely to influence
patterns of murre attendance and reproduction: Bald Eagle (Haliaeetus leucocephalus)
visitation and the onset of an intense El Nifio, did not appear to manifest significant colony-
wide effects. Although eagles were responsible for poor attendance and reproductive
performance of one cliff-top subcolony, they were present in lower numbers than in
previous years and did not hunt along the crevice subcolonies as they had in 1996. The
fact that only 25 stolen murre eggs were observed/recovered (as opposed to 239 in 1996)
provides indirect evidence that eagle effects were lower. El Niito effects would most likely
be manifested as depressed reproductive success, including egg abandonment and chick
starvation. Although several chicks on monitored plots died (11 out of 128), the vast
majority fledged in a mean of 25.7 days, an equivalent value to fledging age in 1996.


Gulls (early in the season) and their chicks (later in the season). By comparison, in 1996,
25 murre kills were either observed or inferred (Parrish 1997). Eagles were also not
observed harassing the crevice subcolonies, as was the case in 1996, and reproductive
success in these nesting areas rebounded from a low of 3% to a high of 87%. No

temporary evacuations of murres from the monitored crevices as a result of eagle presence
were witnessed.

However, eagles were observed continually harassing the PI subcolony and daily
evacuations were witnessed through late June. Eagles landed on this subcolony several
times and established two regular roosts to the immediate south and east of the nesting area,
within sight of the murres, On several occasions, I witnessed an immature eagle flying
from the south perch into the PI nesting area, landing in the area, and retuming to the roost
several minutes later. This behavior was repeated several times over the course of an hour,

until no murres remained on PI.

Aircraft - In 1997, we recorded 25 aircraft overflights (9 helicopters, 15 planes, and one
unknown craft; Table 4) from 11 June through 25 August. This is a minimum number as
all overflights with the potential to disturb seabirds were not recorded and we did not have
complete temporal coverage over the nesting season. Planes and helicopters traveling
adjacent to or over the island above the 2000 ft ceiling maintained by the Olympic Coast
National Marine Sanctuary also were not recorded. Of the 25 recorded overflights, 15
provoked an alarm response by the murres and/or other species nesting on or using the
island, including: Glaucous-winged Gulls, Pelagic Cormorants, Peregrine Falcons, and
Bald Eagles. The majority of these responses were minor, involving standing and
headbobbing (murres). On four occasions, aircraft provoked partial or total evacuations of
one or more species (Table 4). In general, higher levels of response were provoked by
low-flying craft which remained in the area for greater than 2 minutes. Louder craft (e.g.,
helicopters as opposed to planes) also tended to provoke elevated levels of response, given
the above conditions. Although the number of recorded overflights was lower than in 1996
(31), the number of incidents provoking response was both absolutely and relatively higher
(15 compared to 10, 60% compared to 32%). However, the general level of response in
1997 was lower (headbob as opposed to movement or evacuation) and no murre egg or

chick loss was observed.

Oil - There was no sign of oiling during the 1997 nesting season.


indication that changing upwelling structures along the Pacific coast might be depressing
zooplankton and baitfish populations normally the prey of many seabird species.

However, on Tatoosh the murre population did not appear to be overtly affected by this
growing physical anomaly. On the contrary, breeding phenology and fledging age was not
markedly different from previous years and reproductive success was markedly higher in
all monitored subcolonies. Data on murre chick feeding rates, prey species identification
and size, and adult foraging range collected during 1997 all indicate that food was not
limiting in the Tatoosh area (Parrish unpub. data). This supports the theory that the area
around Tatoosh is an oceanographic “hotspot” which may buffer regional events, at least
initially (Parrish et al. 1998). However, as the majority of demographic change associated
with the 1982-83 El Nifio did not manifest itself until the second season, it is not at all clear
that the seabirds nesting on Tatoosh are immune to oceanographic dynamics. Monitoring

of the 1998 nesting season will provide crucial information on the point.

CONCLUSIONS

In 1997, the Common Murre population nesting on Tatoosh Island experienced a slight
depression in attendance but a dramatic increase in reproductive success relative to the 1996
season. Levels of eagle harassment were lower, as indicated by lower numbers of
witnessed kills, recovered carcasses, and stolen murre eggs. The growing El Nifio also did
not appear to significantly, or even marginally, affect the colony’s demographics. Aircraft
disturbance, although slightly elevated in occurrence from 1996, appeared to provoke a
lesser response in general. There was no sign of oil-related disturbance. Finally, we did
not witness disturbance due to human visitation, a consequence we attribute to the near
continuous presence of researchers (both seabird and intertidal) on the island, as we did
receive ten’s of visitors during the 1997 season.

The Tatoosh murre population has been monitored since 1991, providing the longest record
of attendance and reproductive data for murres nesting in Washington State. These data are
useful, in conjunction with the outer coast attendance data collected by US Fish & Wildlife
Service (Ulrich Wilson) and the at-sea distribution and abundance data collected by
Washington Department of Fish & Wildlife (Chris Thompson), in providing managers
tasked with stewardship and restoration basic information on the stability end long-term
integrity of one of the State’s species of concern. These data are also useful, in conjunction

with similar colony data collected at long-term monitoring sites in California (Farallon

18


on MCT-EXT, 11 August on PETCOL, and 27 August on the CC crevices. The pattern of
extended laying and demonstrably later hatching on the crevice as compared to the cliff-top
subcolonies was also the case in 1996.

Chick Fledging Period - Known aged chicks fledged after 26.5 + 2.8 days from MCT-

EXT (N=17) and 25.2 + 1.9 days from PETCOL (N=24). These periods are not

statistically distinguishable (two-sided t-test, T=1.6624, df=39, 0.2>p>0.1). Fledging age
of the MCT-EXT chicks was also marginally longer than mean chick age in 1996, albeit not

statistically so (25.2 + 1.6 days; N=17; two-sided t-test, T=1.6619, df=32, 0.2>p>0.1).

Chick Fledging Phenology - The first chick fledged on 6 August from PETCOL, six days
before the last egg hatched. First fledging on MCT-EXT occurred on 9 August. Fledging
on the CC crevices had not started by 14 August, although several chicks had fledged by
23 August. Based on mean age on known-aged chicks, we estimate fledging began by 15
or 16 August. Mid-range fledging occurred between 10 and 18 August on PETCOL and
19 to 28 August on MCT-EXT. In 1996, mean fledging on MCT-EXT occurred on 18
August, slightly earlier than in 1997. The last chick fledged from PETCOL on 29 August.
After 30 August, 3 chicks remained on MCT-EXT and nine chicks remained on the CC
crevices. No birds were present on the colony when blinds were removed on 18
September.

REPRODUCTIVE SUCCESS

Cliff-top Subcolonies - On MCT-EXT 66 pairs were followed, all of which laid eggs.
Nine eggs were lost or abandoned late in the season as probable duds, the remaining 57
eggs hatched into chicks. Gulls were observed taking three eggs. Of the chicks, 5 died,
49 definitely fledged and 3 chicks remained - two of which were probable fledgers and one
of which certainly died as it was 45 days old when we left and had been abandoned for
several days. Fledglings per pair ranged from 0.74-0.77, well above 1996 (0.54-0.63;
Table 3).

Reproductive success on PETCOL was similarly high. Of 85 pairs followed (all of which
laid eggs), 14 were lost or abandoned and the remaining 71 hatched as chicks. Gulls were
suspected of taking one egg. Five chicks died and the remaining 66 fledged. Fledglings
per pair was 0.78, significantly higher than in 1996 (0.18-0.28; Table 3).

13


the middle 50% of each breeding period took place. In practice, this measure was
estimated rather than measured, according to forward (for hatching) or backward (for
laying) calculations using average egg incubation time or average chick fledging time (for
fledging). Incubation period and fledging age were calculated for known-age eggs/chicks,

Reproductive success was assessed as fledglings per pair, as in previous years. For
crevice subcolonies (CC1-4) all distinguishable pairs were followed and the fate of eggs
and chicks determined. Because it was often impossible to clearly see eggs or young
chicks, due to remote observation and inclement weather, strict measures of breeding
phenology (that is, known-age eggs/chicks) and accurate egg loss were impossible to
determine. As in past years, fledging was defined as either actual fledging observed or
chick healthy and older than 15 days (a probable fledger). The majority of the chicks
actually fledged unless otherwise noted. For the cliff-top subcolonies (MCT-EXT and
PETCOL), the reproductive fate of all pairs within plots adjacent to the blinds were
followed. Due to observer proximity, daily presence of eggs or chicks was easy to
determine and measures of both breeding phenology and hatching success are
correspondingly stronger as compared to the crevice subcolonies.

RESULTS

ATTENDANCE

Colony Estimate & Trends - In 1997, the colony-wide attendance estimate for afternoon
counts after egg laying began but before chick fledging started, was 3204 the lowest value
since we started estimating colony attendance (1991) and an 8% decrease from 1996 (3467:
Table 2; 1996 divided by 1997). Unlike in past years, we were able to count all
subcolonies during the afternoon and did not have to apply morning-to-aftemoon correction
factors in determining our estimate.

All 39 subcolonies present in 1996 were also attended in 1997. Of these, the majority (22)
had lower attendance (sign test, Co¢,9,35=12, 0.5<p<0.2). The majority of these attendance
declines were small. The drop in colony-wide attendance was primarily driven by a large
decrease (-632) in attendance on PI which went from 1284 birds in 1996 to only 652 in
1997. This decline was balanced, to some degree by an dramatic increase in the number of
birds attending PETCOL (+450) and a smaller increase in birds attending MCT-EXT

(+50). In general, the cliff-top subcolonies appeared more volatile in attendance relative to
the crevice subcolonies, a pattern typical of previous years (Table 1).


METHODS
Methods used in 1997 to collect data on Common Murre attendance, phenology, and
reproduction on Tatoosh Island were not substantively different from previous years. As

these have been covered in detail elsewhere (Parrish 1997 and earlier reports), only year-
specifics will be covered herein.

Personnel - In addition to Parrish, two technicians (Karen Jensen and Suzanne Romain)
and three students (Brian Walker, Karen Mabry, and Jessica Tam) collected murre data in
1997 (Figure 1). An additional student (Monica Cameiro Da Silva) assisted in pre-nesting
period trips to erect blinds and check for early eggs (total pre-season: 2 trips, 6 calendar
day's, 12 person days). A trip was also made in mid-September in the company of RT
Paine and his students, to take down blinds for the season (total post-season: 1 trip, 2
calendar days, 2 person days). These latter trips are not recorded on Figure 1. Two
additional students (Teresa Bomersbach and Laura South-Oryshchyn) helped with data
entry and analysis.

Seasonal Coverage - During the breeding season, data were collected between 10 June and
29 August for a total of 51 calendar days and 115 person days (Figure 1). This coverage
approximates the 1996 season. Our three main observation posts were Burning Barrel
Point (BBPT), a set of plywood and one-way mirrored blinds (see Figure 4 Parrish 1997)
situated along the live salmonberry edge of the Main Cliff-top Extension subcolony (MCT-
EXT), and a second set of plywood and one-way mirrored blinds similarly Situated at the
Petrified subcolony (PETCOL). Observations were made for in units of 1/2hr blocks,
spaced evenly throughout the day and season. BBPT was the site from which we collected
hourly attendance data on the monitored crevice subcolonies (Crisscross: CC1-5;
Tenniscourt: TC1-4) as well as phenology and reproduction data on CC1-4 (9 hr of
observation between 0600H and 2200H). Blinds were used as observation sites from
which phenological and reproductive data on all pairs within defined subplots of the
subcolony were collected (MCT-EXT: 124hr of observation between 0600H and 2000H;
PETCOL: 113hr of observation between 0600H and 2000H). Note that lower light levels
as a consequence of salmonberry shading and darkened mirror glass prevented observation
past 2000H. Additional data on attendance and reproduction were collected at sites
throughout the Island; however, no specific record of hours were kept.



INTRODUCTION

In 1997, we continued to collect basic demography data on the Common Murre (Uria
aalge) population nesting on Tatoosh Island, Washington. Data collection specifically
addressed colony size (annual attendance) and reproductive success. To that end, data
were collected which overlapped the methods and sites used in previous years (1991-1996)
to maximize comparative accuracy. As the Tatoosh murre colony was the closest colony to
the Tenyo Maru oil spill, murres were the largest fraction of avian carcasses recovered
immediately following the spill, and the estimate of murre attendance fell in the years
following the spill there is good circumstantial evidence that the oil spill affected this
colony. However, there are other factors which have had significant influence on the
health of the Tatoosh colony, notably the presence of Bald Eagles (Haliaeetus
leucocephalus) which prey upon adults murres and indirectly facilitate substantial egg loss
to Glaucous-winged Gulls (Larus glaucescens) and Northwestern Crows (Corvus
caurinus; Parrish 1995). In past years, eagle-facilitated egg predation has led to chronic
reproductive failure of at least one of the largest subcolonies on Tatoosh (Parrish 1995,
Parrish and Paine 1996) and may be responsible for the high degree of volatility in cliff-top
subcolony attendance seen on Tatoosh (Parrish, unpub. data). Nevertheless, the colony as
a whole has remained fairly stable in size and has produced fledglings in all years since
observations began (1991).

In addition, there is concern that physical oceanographic changes may affect colony
attendance and reproductive success. Cyclic anomalies exemplified by the El Nifio-
Southern Oscillation (ENSO) periodically warm ocean temperatures (the El Nifio half of the
cycle) to several degrees above normal. Such conditions were apparent in 1992 and 1993
and again in 1997. Because ocean warming is a harbinger of lessened upwelling, there is a
correlation between warmer temperatures and less productive oceanic systems (Barber &
Chavez 1986). Trophic dynamics may be altered as the effects of bottom-up control ripple
through the system essentially depressing the food resources for upper-level trophic
predators such as seabirds (Ainley et al. 1995, Hodder & Graybill 1985, Wilson 1991).
Continual monitoring of a colony such as Tatoosh is valuable to document the effects of
such large scale perturbations as El Nifio, as well as to collect baseline information on

murre numbers and long-term reproductive output in a sensitive area of coastline.

This report documents the data collected during the 1997 nesting season, presents a
comparison to earlier years, and provides a brief analysis of the factors influencing the
Tatoosh murre population relative to other known murre colonies along the Pacific Coast.


Table 3 - Tatoosh Island Common Murre reproductive output in crevice subcolonies (1992-
1997) as monitored from BBPT and cliff-top subcolonies (1996-1997) 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 chicks greater than
15 days old (crevices - early years). A range of fldglings/pair encompasses known to have
fledged to known + probable fledging.

1992 1993 1994 1995 1996 1997

ccl

Attendance (aft) 31 28 29 38 39 35
Known Pairs 15 11 22 18 19 17
Known Lost Eggs 2 1 1 1 10 4
Chicks > 15D 11 7 20 17 . 2 13
Fledglings/Pair .73 64 91 94 ll .59-.76
cc2

Attendance (aft) 36 30 35 54 59 36
Known Pairs 17 9 21 15 18 21
Known Lost Eggs 2 4 2 12 17 3
Chicks > 15D 16 2 18 11 0 17
Fledglings/Pair 94 22 86 73 0.0 81
cc3

Attendance (aft) 30 17 27 57 60 42
Known Pairs 11 2 7 20 24 29
Known Lost Eggs 0) 2 6 3 15 1
Chicks > 15D 7 0 1 17 0 28
Fledglings/Pair 64 0.0 14 85 0.0 -93-.97
cc4

Attendance (aft) 13 17 21 21 13
Known Pairs 6 7 7 “10 8
Known Lost Eggs 1 0 0 10 1
Chicks > 15D 3 6 7 0 2 (6)
Fledglings/Pair 50 86 1.0 0.0 0.0-.75
MCT-EXT

Known Pairs 65 66
Eggs Seen ‘ 64 66
Known Lost Eggs 22 9
Chicks 42 57
Fledgers (known;suspected) 35:6 49:2
Fledglings/Pair 54-63 .74-.77
PETCOL

Known Pairs 39 85
Eggs Seen 45 85
Known Lost Eggs 26 14
Chicks 13 71
Fledgers (known;suspected) 7:4 66
Fledglings/Pair -18-.28 78



accuracy increased over time (i.e. a learning curve), early counts (defined as the first three
full days of counting a given set of subcolonies) were not included in the final datasct.

In 1997, all attendance data were direct counts, except for Pole Island (PI) at which an
approximate 1/4 of the total subcolony was visible. As in previous years, the PI count was
multiplied by 4 to obtain the PI attendance estimate. All subcolonies were counted from
locations on Tatoosh Island with the exception of the Toadpoint crevice and cliff-top
subcolonies (TP1-4, TPCT 1-2), and Rainbow Rock (RR) 1-2 which were counted from
the deck of the OCNMS RV Tatoosh and a smaller private boat. During these boat trips,
photographs were taken for later counting and verification. The photographic counts were
used instead of direct counts for the TP and TPCT subcolonies as the latter were of lesser
quality (greater than 10% variation both within and between observers) due to wave action
close to the Island. Photographs of all other subcolonies were only used for verification
and documentation purposes. Although counts were made in both the morning and the
afternoon (as in previous years), during 1997 all subcolonies were counted more than once
during the afternoon. To minimize errors introduced during standardizations, only

afternoon counts were used to estimate annual colony attendance.

As in previous years, it was necessary to count several subcolonies from multiple locations
as the entire crevice could not be seen from any one place. These included: CC 4 and 5,
and TC 3. For these subcolonies, distinctive rock features were used to mentally mark the
limits of observation from the main counting platform (BBPT) and the remaining birds
were counted from additional sites. Because these subcolonies are part of the monitored
crevice subcolony complex (CC1-5; TC 1-4), different attendance values are reported
herein depending on analysis. For the Island-wide annual attendance estimate, totals (that
is, a combination of counts from more than one location) were used. For the daily and
seasonal attendance patterns analysis, only the BBPT counts were used.

Breeding Phenology & Reproductive Success - In 1997, laying was fairly synchronous
within subcolony, but not among subcolonies. Consequently, there was virtually no day
during which laying, hatching, and/or fledging were not occurring. Because the field
accommodations on the island are shared with RT Paine and his colleagues, we were not
able to remain on the island throughout the season and there are gaps in our records (Figure
1). This prevented us from accurately estimating mean laying, hatching, and fledging as
was the case in 1996. Instead, the 1997 measure includes the actual or estimated range of
laying, hatching, and fledging (comparable to 1996 data) and the calendar days over which



Attendance and Reproductive Success of Tatoosh Island Common Murres

Final Report 1997
April 1998

Julia K. Parish

Zoology Department, Box 351800
University of Washington
Seattle, WA 98195
jparrish@u.washington.edu

prepared for the Tenyo Maru Trustees Council
Prinicipal Investigator: Julia K. Parrish
Technicians: Karen Jensen
: Suzanne Romain
Student Employees: Jessica Tam
Karen Mabry
Laura South-Oryshchyn
Teresa Bomersbach
Student Volunteers: Brian Walker
Monica Cameiro Da Silva


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160 170 180 190 200 210 220 230 240 250
June 15 July 1 August I September 1

Julian Day

Figure 1. Days spent on Tatoosh Island during the 1997 Common Murre breeding season
and murre breeding phenology (L=laying, H=hatching, F=fledging) as assessed during
those trips. Dashed lines are dates noted below the Julian Day axis. Filled:boxes indicate
presence of specified observers. For the two cliff-top subcolonies (MCT-EXT,
PETCOL), range and middle two quartiles (50%) are indicated. For the crevices
subcolonies (CC1-4), only range is indicated. The arrow indicates probable fledging
beyond 29 August. Numbers in () indicate how many chicks were left in the nesting

area survey plot after 29 August. There were also a ditional chicks outside of the survey
plot on MCT-EXT after 29 August.

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Attendance - All observers who collected attendance data were required to count in the
presence of an experienced counter (Parrish, Jensen) until counts were within a maximum
difference of 10%. In practice, most counts were more similar. In addition, all counters
were required to make spot multiple counts, to check for intra-observer accuracy. For
experienced observers counting large (defined as over 100) subcolonies, accuracy was
consistently at or less than 2% difference. For in-experienced observers, accuracy was at
or less than 5% difference. Becaus in-experienced observers were more variable, all of

their counts were lower than the experienced observers, and their intra- and inter-counting


Table 4 - Aircraft disturbance of breeding Common Murres on Tatoosh Island in 1997. Of
25 recorded incidents in which aircraft flew over the island (9 helicopters; 15 planes, 1
unknown), 15 provoked an alarm response.

Aircraft Type Height* Duration of Stay** _ Murre Response

unk* unk short headbob
helicopter unk long headbob
helicopter unk short headbob
helicopter unk short headbob
helicopter unk unk headbob
plane low short headbob
plane low short headbob
plane low unk headbob
plane unk short headbob
plane unk unk headbob
plane unk unk headbob
helicopter low long partial evacuation
helicopter low long partial evacuation
plane low long partial evacuation
helicopter lands long partial/total evacuation**
*Height estimated relative to the OCNMS 2,000 foot ceiling
** Duration arbitrarily divided into less than two minutes (short) or greater (long).
* Heard only.

** Murres, gulls, and cormorants - partial evacuation; one Peregrine Falcon and one
juvenile Bald Eagle flushed.
*** Partial evacuation by murres, total evacuation by gulls and cormorants.

Food Availability - Early in 1997 the tropical Pacific experienced a significant increase in
sea surface temperatures associated with what is now being called the most significant El
Nifio of the century (NOAA, www.ogp.noaa.gov/enso). Persistently elevated sea surface
temperature can be a harbinger of depressed primary production and ensuing trophic
collapse because the former is indicative of a shift in upwelling strength, the phenomenon
which drives much west coast productivity. The 1982-83 El Nifio was associated with
dramatic depressions in murre attendance, breeding phenology, and reproductive success
(Boekelheide et. al. 1990, Sydeman 1993), colony abandonment (Wilson 1991), and death
(Hodder & Graybill 1985) throughout the Pacific coast of North America, albeit primarily
in the second season (1983)-and thereafter (1984). Elevated sea surface temperatures and a
significant shortening of the upwelling season along the Oregon coast were recorded in
1997 (Newport line data; R Smith pers. comm. to JKP). Thousands of murre and
Cassin’s Auklet, Prychoramphus aleutica, carcasses were recovered on Washington outer
coast beaches during the summer of 1997 (CW Thompson pers. comm. to JKP 1997), an

17


LIST OF FIGURES AND TABLES

Figure 1. Schedule of island visitation and Tatoosh Island Common Murre breeding
phenology, 1997.

Figure 2. Attendance of Tatoosh Island Common Murres on nine monitored crevice
subcolonies over the day (0600-2000H), 1997.

Figure 3. Attendance of Tatoosh Island Common Murres on nine monitored crevice
subcolonies over the season (11 June - 14 August), 1996.

Table 1. Estimated afternoon annual attendance by subcolony of Tatoosh Island Common
Murres, 1991-1997.

Table 2. Average annual attendance counts from BBPT of monitored creyice subcolonies,
1991-1997.

Table 3. Reproductive output of Tatoosh Island Common Murres in monitored crevice
(1992-1997) and cliff-top (1996-1997) subcolonies.

Table 4. Aircraft type and response of Tatoosh Island Common Murres, 1997.


Table 2 - Average of attendance counts made from BBPT (1991-1997) during egg/chick period for
monitored crevice subcolonies.

MornX MornSD MornN Aft X Aft SD AftN

1991 crisscross 1 24.50 8.67 3 38.50 16.26 2
crisscross 2 16.83 4.54 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
crisscross 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 1 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 7.76 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 4.51 13 21.25 4.80 16
TOTAL 254.70 328.05


Seasonal attendance patterns in 1997 differed widely from 1996, no surprise given the
intense eagle harassment of the crevices in 1996 but not in 1997. Afternoon attendance
was stable throughout the nesting period, while morning attendance was depressed
primarily during the egg laying period (Figure 3). Note the extreme variability in
attendance prior to egg laying, both well below and above the mean (390.7).

PHENOLOGY

Egg Laying Phenology - Nine eggs were present on MCT-EXT on 12 June and eggs
appeared on PETCOL by 14 June and the CC crevice subcolonies by 16 June (Figure 1).
Final eggs appeared sometime after 27 June on the cliff-top subcolonies (MCT-EXT 7
additional eggs; PETCOL 25 additional eggs) and 14 July on the CC crevice subcolonies.
Figure | indicates laying range and the days over which the middle 50% of the eggs were
laid (cliff-top subcolonies only). Mean lay dates were not calculated as a significant
fraction of followed eggs were laid in our absence. In 1996, egg laying appeared to be
slightly earlier. Mean lay date on MCT-EXT was 18 June in 1996, as compared to
between 21 and 29 June in 1997. However, PETCOL laying phenology was slightly
accelerated - the middle 50% of followed eggs were laid between 15 and 22 June.

Although laying was marginally earlier in 1996, it was also more protracted due to
exceedingly high egg loss (last egg laid on 1 August). In 1997, only 25 eggs were
observed taken by predators, smashed below subcolonies, or as eggshell fragments in
paths in the interior of the island (probable crow food), as compared to 239 eggs in 1996
(observations collected over a comparable period of effort). :

Egg Incubation Period - Mean egg incubation was 31.7 days with a standard deviation of
1.3 days for known-age eggs on both the MCT-EXT (N=9) and PETCOL (N=16). This is

slightly shorter than mean incubation period for 1996 (32.2 + 0.9; N=17), albeit not

significantly so (two-tailed t-test, T=1.473, df=40, 0.2>p>0.1). Biologically, however,
this difference translates into less than a single day.

Chick Hatching Phenology - Chicks appeared on the PETCOL on 12 July and 15 July for
MCT-EXT. On the crevice subcolonies, no chicks were present on 19 July although
several had hatched by 26 July (Figure 1). Mid-range of hatching occurred between 17 and
23 July on the PETCOL and 24-30 July on MCT-EXT. In 1996, mean hatching on MCT-
EXT was 24 July, perhaps slightly earlier than in 1997. Final eggs hatched on 7 August


TABLE OF CONTENTS
Cover Page
Acknowledgments
Table of Contents
List of Figures and Tables
Executive Summary
Introduction
Methods
Personnel
Seasonal Coverage
Attendance
Breeding Phenology & Reproductive Success
Results
Attendance
Colony Estimate & Trends
Multiple Count Subcolony Attendance
Phenology
Egg Laying Phenology
Egg Incubation Period
Chick Hatching Phenology
Chick Fledging Period
Chick Fledging Phenology
Reproductive Success
Cliff-top Subcolonies
Crevice Subcolonies
Non-Monitored Subcolonies
Factor Affecting Murre Demographics
Eagles
Aricraft
Oil
Food Availability
Conclusions
References

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ACKNOWLEDGMENTS

The author wishes to thank the Makah Tribal Nation and the U. S. Coast Guard for
continued access to Tatoosh Island. R Smith provided information on patterns of coastal
upwelling and sea surface temperature off Newport, Oregon. CW Thompson provided
information on carcass recoveries along the Washington outer coast. RT Paine provided
needed field and laboratory assistance, logistics, and accomodations. Additional logsitical
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 (JK
Parrish). Additional financial support was provided by a Washington Sea Grant 1997 pilot
grant to JK Parrish and CW Thompson, a Washington Sea Grant grant to JK Parrish, a
University of Washington Royalty Research Fund grant to JK Parrish, and a National
Science Foundation grant and Mellon Foundation support to RT Paine.



There were three new subcolonies born in 1997: two crevices - Toadpoint (TP) 4, Finger
(F) 2, and one cliff-top - Rainbow Rock Top (RR-TOP). Although all of these subcolonies

were small (total additional attendance of 47 birds), at least two (RR-TOP, F2) produced
chicks (Table 1).

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Figure 2. Attendance summed across CC1-5 and TC1-4, as counted hourly. Data are
from the period after murres remained on the crevices throughout the day and before
fledging from the crevices (17 June - 10 August 1997), and are limited to only those
hours in which all relevant crevices were counted (i.e., no partial counts). A Student's
t-test on morning versus afternoon means indicates there were significantly fewer murres
in attendance in the morning (see text for complete statistics). The dashed line indicates
the morning-afternoon division.

Multiple Count Subcolony Attendance - As in past years, the CC and TC crevices were
counted on the hour over the day and season to determine patterns of attendance as a
function of time of day, breeding phenology, and to statistically test interannual
differences. For counts made after the onset of egg laying but before the onset of chick

fledging (17 June through 10 August - the nesting period), morning values (326.2 + 54.3;

N=27) were significantly lower then afternoon values (390.7 + 21.9, N=44; T = -5.882, df

= 31,2; p < 0.001, separate variances; Figure 2), a pattern repeated in all earlier years


Table 2 - Average of attendance counts made from BBPT (1991-1997) during egg/chick period for
monitored crevice subcolonies.

1995 crisscross 1 36.57 4.72 7 37.82 3.84 11
crisscross 2 41.43 8.62 7 53.82 12.29 11
crisscross 3 49.71 11.79 7 57.09 8.07 11
crisscross 4 19.57 5.09 7 21.00 5.51 ll
crisscross 5 100.52 13.61 7 114.00 14.81 1
tenniscourt 1 35.57 6.21 7 40.09 3.94 11
tenniscourt 2 20.86 3.98 7 25.73 3.44 ll
tenniscourt 3 72.00 12.68 7 77.00 8.45 ll
tenniscourt 4 15.86 2.97 7 19.45 5.57 lL
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 I4
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 7.49 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: Attendance data for 1996 from 12 June through 3 July 1996 only.

1997 crisscross 1 30 49 28 34.64 3.15 47
crisscross 2 29.32 7.46 28 35.87 6.85 47
crisscross 3 35.64 11.14 28 42.17 5.35 47
crisscross 4 10.64 27 28 13.21 "2.13 47
crisscross 5 88.46 10.79 28 97.6 8.73 47
tenniscourt | 24.15 7.04 27 31.38 3.03 45
tenniscourt 2 19.04 6.19 27 26.4 3.43 45
tenniscourt 3 67.18 10.56 27 83.91 6.68 45
tenniscourt 4 21.74 3.97 27 26.29 3.51 45
TOTAL 326.17 391.47

Note: Attendance data for 1997 from 17 June through 10 August only
Note: TC3 attendance is smalle than in Table 1 because a newly colonized portion of this
crevice was not visible from BBPT.

General Note: The counts for CC1, 4, and 5 are lower than in Table 1 because none of
these crevices were entirely visible from BBPT.