181

Movements of Crows in Urban Areas,
Based on PHS Tracking
Emiko MORISHITA1, Kiyoshi ITAO2, Ken SASAKI2 and Hiroyoshi HIGUCHI1
1

Graduate School of Agriculture and Life Sciences, The University of Tokyo
1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
2
Graduate School of Frontier Science, The University of Tokyo

Abstract
Few ecological surveys of jungle crows (Corvus macrorhynchos) have been done in urban areas
because it is difficult to track them, but we have succeeded in tracking the crows using a recently
developed technique, attaching a PHS (Personal Handyphone System) location device, in Tokyo and thesurrounding area. We classified their daily home ranges into roosts, morning habitations, and diurnal
habitations. We analyzed their daily movement patterns, and classified them into sedentary and two
migrant types. Their flight distances were longer in the non-breeding season than in the breeding
season. The crows were assumed to disperse to new areas in the non-breeding season. Though PHS
tracking has several problems such as short battery life, it is a useful technique for obtaining detailed
data on large birds’ movements in urban areas.
Key words: dispersion, jungle crow, PHS, tracking

1. Introduction
In recent years crows have posed problems tohumans in urban areas in Japan. Crows, especiallyjungle crows (Corvus macrorhynchos, hereinafterreferred to as crows), are associated with human activities in urban areas, resulting in some conflicts between humans and crows (Higuchi & Morishita, 2000;
Kawachi & Endoh, 2000; Matsuda, 2000). For
example, crows scavenge and scatter food scraps fromplastic bags put out at garbage collection stations on
the streets, and in the breeding season some crows
attack people passing by their nest trees.
To solve these problems, the Government carriedout the following project. Since 2000, to addresshuman-crow conflicts, the Tokyo Metropolitan Government has removed eggs and chicks from the nestsof crows. Since 2001 they have captured crows, using cage traps, to control their numbers. However,these projects have only stopgap effects. For fundamental solutions, ecological surveys of crows are
required in order to allow for the appropriate management of and effective measures against crows.
Few ecological surveys of crows have been carriedout, partly because it is difficult to track crows inurban areas. Radio telemetry techniques are usuallyused to track birds. In this technique, a transmitter is
attached to a bird, and a tracker follows it using anantenna and a receiver. This technique, however, is
not suitable for tracking crows in urban areas, because

many concrete buildings often block radio waves, andcrowds of people and heavy traffic make it difficult totrack them. In addition, when a crow has flown
some kilometers away without a stop, a tracker cannot
easily catch the radio signals again.
In this study, we used a PHS (Personal Handyphone System) location device, which solves the
problems radio telemetry poses in urban areas. A
PHS, developed in recent years, enables a tracker tolocate crows at any time of day for about 1-2 weeks
by automatic locating (Nagato et al., 2000; Takasaki etal., 2000; Higuchi, 2001; Kurusu, 2002; Misumi et al.,2002).
Using a PHS location device, we studied the daily
movement patterns and seasonal differences in flying
distances of jungle crows in Tokyo and the surrounding area. In this paper, we report the results and discuss the effectiveness of PHS location devices inecological studies.

2. Study Areas and Methods
2.1 Study areas
Crows were captured in Ueno Zoological Garden,
Tokyo, Japan (35°43’N, 139°46’E), using cage traps.
Ueno Park, where the zoo and some museums arelocated, has an area of 534,137m2 (Fig.1). Trees in
the park include Cherry (Prunus yedoensis), Ginkgo(Ginkgo biloba), and Zelkova (Zelkova serrata).
Lake Shinobazu, where ducks winter, is located in the

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southwestern part of Ueno Park. Crows use the park
as a communal roost during the night, and some crows
stay there during the daytime for resting and foraging.
We found some crow nests in the park in the breeding
season.
2.2 Capture and release
The cage traps we used have entrance holes on the
top. Crows can easily enter the cages through the
openings, but they are prevented from exiting by wires(about 50 cm in length) dangling from the entrance
holes. A total of 23 crows were released in 2001,
with 3 crows released on April 20, 4 crows on April

28, 3 crows on May 2, 4 crows on November 26, 5
crows on December 3 and 4 crows on December 14.
Out of the 23 crows released with PHS transmitters,
18 birds were tracked successfully, and the rest 5
crows returned to the cage trap on the day after they
were released. These 18 crows were all assumed tobe juveniles (9-11 months old in the breeding season,
4-6 months old in the non-breeding season), because
the color in their mouths was not black (c.f. Kitagawa
1980). Table 1 shows the tracking data of the 18
crows. We tracked them for 4-19 days (9.7 days ±1.1 (s.e.): n=18). Since the tracking period was short,the location data were analyzed for each day. The

Fig. 1 Map of the study area.
Table 1 Summary of PHS tracking of jungle crows, from Ueno in 2001.
ID
1
2
3
4
5
6
7
8

PHS type
P-doco?mini
P-doco?mini
P-doco?mini
P-doco?mini
P-doco?mini
P-doco?mini
P-doco?mini
P-doco?mini

Starting date
April 20
April 28
April 28
April 28
April 28
May 2
May 2
May 2

Tracking days
13
5
6
4
6
7
10
8

Number oflocations
494
167
196
115
154
165
375
152

Type of movement*
Sedentary type
Sedentary type
Sedentary type
Sedentary type
Sedentary type
Sedentary type
Migrant type
Sedentary type

9 Upgraded type of "P-doco?"
November 26
5
113
Sedentary type
10 Upgraded type of "P-doco?"
December 318566
Migrant type
11 Upgraded type of "P-doco?"
November 26
15
456
Migrant type
12 Upgraded type of "P-doco?"
November 26
5125
Migrant type
13 Upgraded type of "P-doco?"
December 3
8
202
Migrant type
14 Upgraded type of "P-doco?"
December 3
7120
Migrant type
15 Upgraded type of "P-doco?"
December 1414435
Migrant type
16 Upgraded type of "P-doco?"
December 3
19595
Migrant type17
P-doco?mini
December 1411349
Migrant type18
P-doco?mini
December 1414491
Migrant type
* Sedentary types had overlapping estimated home ranges under our kernel method during the tracking period.
Migrant types changed home range roosting areas and foraging areas.

Movements of Crows in Urban Areas, Based on PHS Tracking

results were compared between the breeding andnon-breeding seasons.
As a pilot study, we weighed 7 trapped crows andharnessed them with dummy PHS transmitters similarin shape and weight. We also attached wing tags andcolor leg rings to the crows. We kept them in one of
the trapping cages for 6 days to observe how theywould react to the dummy transmitters. We counted
the number of times the crows pecked at the dummies
over a course of 30-50 minutes once each day during
the observation period.
Selecting crows that
displayed no ongoing reaction to their dummytransmitters, we replaced the dummies with realtransmitters, and released the birds. All of the crows
were kept in the trapping cage for a week with thedummies before release. The PHS transmitters wereattached to the crows by Teflon-treated ribbons,(Telonics Inc., U.S.A.)
The transmitters used in the study were developedby the Nippon Telegraph and Telephone Corporation(NTT) of Japan.
From April to May 2001,“P-doco?mini” transmitters were used, which were51.0 × 34.2 × 16.3 mm and weighed 27 g. From
November to December 2001, “P-doco?” transmitterswere also used, which were 62.6 × 38.6 × 13.5 mm
and weighed 22 g. The latter ones were upgraded by
Seiko Instruments Inc. of Japan to be lighter and havea longer battery life (Kurusu, 2002). The total
weight of the transmitter package accounted for
4.26% ± 0.12 (s.e) of a crow’s body weight (n=18).
We located the crows every 30 minutes between 3:00
and 20:00.
2.3 Field observations
We also observed the activities of some of thecrows with PHS transmitters, while tracking them by
PHS location devices. Crows No.1, No.8, No.17 andNo.18 were observed in the field over a course of 5-6hours a day for one or two days.
2.4 PHS location devices
The PHS location system operates as follows. The
PHS transmitter continually emits electromagnetic
waves (EMW), which are received by the PHS telecommunications networks system. We can determine which antenna is receiving the EMW from the
PHS transmitter by calling a particular PHS number.
This function enables us to locate the PHS transmitters attached to the crows. The PHS antennas areplaced about 100 m apart. The number of antennas
is large enough in urban areas, but relatively small inrural areas. The location accuracy of PHS depends
on the density of antennas.
An upgraded “P-doco?” type transmitter needs twoantennas for location. A location point is an intermediate position between the two nearest antennas.
In theory, the positional error is 100-200 m in radius.
“P-doco?mini,” on the other hand, needs three or moreantennas for location. A location point is calculated

183

from EMV intensity received at three or more antennas, by the method of triangulation. In theory, thepositional error is 30-40 m in radius (Kurusu, 2002).
A location point for “P-doco?mini” is therefore theoretically more accurate than that for "P-doco?"(Nagato et al., 2000; Takasaki et al., 2000; Kurusu,
2002).
When we compared locating accuracies between“P-doco?mini” and “P-doco?,” however we foundlittle difference. From November to December 2001,
we placed both types of transmitters at 14 locations inand around Ueno Park, and located them 74 times on
average. We calculated the distances between exact
locations and location points indicated by the PHS
locating device.
The calculated distances showed no significant
differences between the two types of transmitters, noramong the 14 places (Freedman two-way analysis ofvariance; 2 transmitters: χ2=0.0714, df=1, p=0.789; 14
areas: χ2=21.714, df=13, p=0.06). We analyzed thedata from the two types of transmitters together,because there was no significant difference between
the transmitters. The locating error was 123.99 m ±
5.8 (s.e.) (n=2084).
2.5 Data Analysis
Location data were compiled by the NTT server at
fixed intervals. We downloaded the data from theInternet and plotted them on a map of Tokyo using
GIS software “Arcview GIS 3.2” (ESRI Inc., U.S.A.).
We estimated 90% fixed kernel home ranges (Worton,
1989), based on daily location data using “Animal
Movement,” an extension program of Arcview GIS
3.2, when we obtained more than 30 location points aday. Daily home ranges estimated by a kernel
method were separated into two or more areas.
We described daily movements by classifying theareas which the crows used, as roost areas, morning
habitations, and diurnal habitations. A roost area
was an area where crows stayed during the night, datafrom sunset to 20:00 and from 3:00 to sunrise. A
morning habitation was an area where crows stayedsoon after leaving their roosts, until one hour after
sunrise. A diurnal habitation was an area where
crows stayed during the daytime from the time theyleft the morning habitation until sunset. Land use of
these areas was classified into urban areas, green
spaces, and riversides from map data. Green spaces
included parks, gardens and cemeteries, and urban
areas included business areas, residential blocks andschools.
We drew flight lines using “Animal Movement,”
an extension of Arcview, and calculated the distances
between the location points. We also calculated theareas of the estimated home ranges. For these data
analyses, we used the Mann-Whitney U-test.
The rate of continuous roost utilization (C) was
calculated from the expression below.
C=S/T

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S is the number of consecutive nights when a crowutilized the same roost. T is the total of nights thecrow was tracked. For the data analysis, we used theMann-Whitney U-test.

3. Results
3.1 Effect of transmitters
We counted how often crows pecked their dummytransmitters to determine the effect of the dummies onthem. The mean pecking rate ( x ) per 10 minutes
was 1.07 on the first day, 0.93 on the second day, 1.5
on the third day, 0.57 on the fourth day, 0 on the fifth
day and 0.36 on the sixth day, showing a slightdownward trend. Since the pecking rates were low
on any of the days, the effect of the transmitters on
crows was assumed to be insignificant.
3.2 Daily movement
Most crows had several separate 90% fixed kernel
home ranges each day (Fig. 2). They stayed twohours or more in each of these separate areas. The
location data of the 18 crows successfully tracked
showed that they used a total of 31 separate places(Table 2 & Fig. 3).
Of these 31 places, 17 were used as roost areas, 18
as morning habitations, and 9 as diurnal habitations(Table 2). Of the 17 roost areas, 10 were green
spaces, 6 were urban areas, and 1 was a riverside. Of(No. 1, 4/29)

the 18 morning habitations, 12 were urban areas, 4green spaces, and 2 riversides. Of the 9 diurnal
habitations, 6 were urban areas, and 3 green spaces(Table 2). Crows seem to have a tendency to roost in
green spaces and to stay in urban areas in the morning.
Statistical tests could not be applied here due tolimited sample size.
We observed crow No. 18 roosting in an area withsparse vegetation in December 2001. In May 2001,
crow No. 1 was scavenging food scraps from restaurants in the urban area until two hours after sunrise.
In December 2001, crow No. 17 was going back andforth between the river banks along Edogawa, whichis the boundary between Tokyo and Chiba Prefectures,
during the daytime. In May 2001, crow No. 8 wasresting on a tree at Yanaka Reien cemetery during thedaytime.
3.3 Movement patterns
On individual movements, two types were observed: a sedentary and a migrant type. In the sedentary type, crows did not change their morning habitations, diurnal habitations or roosts. Crows of the
migrant type, on the other hand, changed one or moreof these areas. The migrant type was further divided
into two subtypes: migrant type 1 and migrant type 2.
Migrant type 1 changed roosts at a distance of 5-15 km,
but their daily movement patterns were similar to thesedentary type during the tracking period. Migranttype 2 consisted of crows that changed their roosts,(No. 14, 12/5)(No. 12, 11/29)

Fig. 2 Examples of daily home ranges. Blue circles are home ranges, blue points are locations,arrows indicate flyways.

Movements of Crows in Urban Areas, Based on PHS Tracking

morning habitations and diurnal habitations every few
days (Fig. 4). In addition to these types, an
exploratory movement was also observed.

185

Hereinafter, we describe the details of movementsof the sedentary type, the migrant type and the exploring movement. Numbers in parentheses following area names are code numbers used in Table 2 andFig. 3.

Table 2 Utilization of 31 areas identified by tracking 18 jungle crows. Utilization by crows is estimated according
to the relationship between land use and time present.
No.

Place name1 Toshima 5 Apartment
2 Ohji Station
3 Rikugien
4 Koishikawa botanic garden
5 Sendagi
6 Yanaka reien
7 Mukougaoka
8 Ueno park
9 Hongo 6
10 Shinobazu lake
11 Okachimachi
12 Ochanomizu
13 Meiji University
14 Kitanomaru park
15 Hanzoumon
16 Tokyo station
17 Arakawa park
18 Nishi-asakusa
19 Shirahige bridge
20 Mukoujima garden
21 Sumida park
22 Oshiage 3
23 Higashi-sumida
24 Kyu-Yasuda garden
25 Kameido 2
26 Kameido park
27 Sarue park
28 Aoto29 Kita-Koiwa
30 Kokufudai station
31 MamaFig. 3

Land use
Urban area
Urban area
Green space
Green space
Urban area
Green space
Urban area
Green space
Urban area
Green space
Urban area
River side
SchoolGreen space
Urban area
Urban area
Green space
Urban area
River side
Green space
Green space
Urban area
Urban area
Green space
Urban area
Green space
Green space
Urban area
Urban area
Urban area
Urban area

Utilization by crow
Diurnal habitation
Morning habitation
Roost
Roost, Morning habitation, Diurnal habitation
Roost, Morning habitation
Roost, Morning habitation
Roost, Morning habitation
Roost, Morning habitation
Morning habitation
Roost
Roost, Morning habitation, Diurnal habitation
Roost, Morning habitation
Diurnal habitation
Roost
Roost
Morning habitation
Morning habitation
Morning habitation
Morning habitation
Roost
Roost
Morning habitation, Diurnal habitation
Roost, Morning habitation, Diurnal habitation
Roost
Morning habitation
Diurnal habitation
Roost, Diurnal habitation
MovingMorning habitation
Morning habitation
Roost, Diurnal habitation

No. of crows
1
1
1
2
1
7
1
18
1
2
12
1
1
1
1
1
2
1
1
1
2
1
4
1
1
1
1
1
1
1
1

Locations of roosts, morning foraging areas and diurnal habitations, used by the 18 crows. Place names,
land use and utilization by crow number are shown in Table 2.

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E. MORISHITA et al.

Crows No.2, 3, 5 and 6 came back to Ueno Park
from their morning habitations in the morning, andstayed in Ueno Park most of the day. Nos.1 and 8
came back to Ueno Park at 15:30 and 18:30
respectively. No.1 stayed in the urban area a longtime, though the crow could not scavenge garbage
after 8:00 in Okachimachi, because many people
passed along the streets at that time. This crow wasobserved staying on the rooftop of a building.

a. Sedentary type
Crows of the sedentary type Nos.1, 2, 3, 5, 6 and 8,
used the same areas during the tracking period.
Their kernel home ranges overlapped. They roosted
in Ueno Park (8), and moved to the streets ofOkachimachi and Ueno 2 (11) in early morning toscavenge food scraps from restaurants. On the other
hand, two of them (No.4 and No.9) did not leave Ueno
Park. In the non-breeding season, however, only one
bird stayed (Figs. 5 & 6).

Fig. 4 Movement patterns of jungle crows during our study.

Fig. 5 Example of sedentary type (crow #5). Blue points are location points, red circles are home ranges
estimated by a kernel method. Double arrow indicates round trips between the areas.

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

4/28
4/29
4/30
5/1
5/2
5/3
：Ueno Park

：Okachimachi, Ueno2：Shinobazu lake

Fig. 6 Example of diurnal habitations and times for crow #5.
Horizontal axis is time, color-coded by habitation. Vertical axis is date.

19

20

21

22

23

24時

Movements of Crows in Urban Areas, Based on PHS Tracking

days after that, the crow moved to the urban area ofHigashi-Sumida (23). No.15 changed its roost from
Ueno Park to Rikugien Garden (3) and its morning
habitation to Toshima 5 Apartment on the twelfth day.
No.16 changed its roost from Ueno Park to
Mukoujima Hyakkaen Garden (20) and its morning
habitation to Higashi-Sumida on the third day.
No.17 moved from Ueno Park to Kokufudai (30) in
Ichikawa, Chiba Pref., on the second day. No.18
changed its habitation from Ueno Park to Ochanomizu(12) and changed its roost to Yushima-seido on the
fourth day.
c. Migrant type 2
Crows of migrant type 2 changed their roosts from
Ueno Park (8) to other areas, and used two or moreroosting sites irregularly. They had several morning
habitations and diurnal habitations, which they usedby turns (Figs. 9 & 10). Migrant type 2 included
Nos.10, 11 and 13. All of these were tracked during
the non-breeding season.
No. 10 left Ueno Park, and went back and forthb. Migrant type 1
Crows of migrant type 1 changed their roost from
Ueno Park (8) to other areas, and used two or moreroosts during the tracking period. In addition to theirroosts, they changed their morning habitations anddiurnal habitations as well. After changing theseareas, the crows stuck to the same areas during the
tracking period. Their kernel home ranges overlapped,
as did those of crows of the sedentary type. Migranttype 1 consisted of crows No.7, 13, 14, 15, 16, 17 and18. Only one crow showed this movement pattern inthe breeding season, while 6 birds did during thenon-breeding season (Figs.7 & 8).
Three crows of migrant type 1 moved from Ueno
Park to the residential areas of Sendagi andMukougaoka (5 and 7). No.13 changed its roost on
the third day, No. 7 on the seventh day and No.17 on
the second day. No.14 changed its roost from Ueno
Park to Koishikawa Botanic Garden (4), and its
morning habitation to the residential area of
Mukougaoka on the second day. Moreover, fourFig. 7

0

187

Example of migrant type 1 movement pattern (crow #17). Blue points are crow location points,
red circles are home ranges estimated by a kernel method. Arrow indicates crow flight path.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

12/14
12/15
12/16
12/17
12/18
12/19
12/20
12/21
12/22
12/23
12/24
12/25
：Ueno park

Fig. 8：Moving：In transit：Higashi-sumida：Aoto：Kita-koiwa

Example of diurnal habitations and times for crow #17.
Horizontal axis is time, color-coded by habitation. Vertical axis is date.

：Kokufudai

24 o’clock

188

E. MORISHITA et al.

between Higashi-sumida (23) and Sarue Park (27).
This crow used the former Yasuda Garden (24),
Higashi-sumida and Sarue Park as roosts. It spenttime on the streets of Higashi-sumida, Oshiage 3 (22)and Kameido 2 (25). No.11 used Ueno Park andKoishikawa Botanic Garden (4) as roosts at 2-3 day
intervals. This crow visited the streets of Hongo 6(9) and Okachimachi (11) at 2-3 day intervals.
No.12 used Ueno and Sumida Parks (21) as roosts,
and spent time mainly on the streets ofHigashi-sumida.

belonged to the sedentary type, they went to the moatsof the Imperial Palace (14, 15), stayed there one night
and came back to Ueno Park the next day. Though
No.18 of migrant type 1 moved from Ueno Park to the
Ochanomizu area (12), it went to Ueno Park from
Ochanomizu twice during the tracking period, but
came back to Ochanomizu after two hours.
3.4 Differences between breeding andnon-breeding seasons
We compared the movements of crows between
the breeding (April to May) and non-breeding seasons(November to December).
The proportions of the sedentary type to migranttypes in the breeding season and non-breeding season(1 : 7 breeding season, 10 : 1 non-breeding season)
differed significantly (Fisher’s exact probability test:
χ2= 3.8415, p=0.0012). Almost all crows belonged
to the sedentary type in the breeding season, andalmost all crows were classified as migrant types in

d. Exploratory movements
Exploratory movements were observed in crows of
the sedentary type and migrant type 1 (Fig. 11).
These types of crows went to other areas and stayed
there for two hours or one night, and then came backto their original areas.
Nos.1, 6 and 18 showed exploratory movements.
Though Nos.1 and 6, which stayed in Ueno Park (8),Fig. 9

Example of migrant type 2 movement (crow #11). Blue points are locations, red circles are homeranges estimated by the kernel method. Arrows indicate round trips among roosts and two morning
foraging areas.
0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24
時 o’clock

11/26
11/27
11/28
11/29
11/30
12/1
12/2
12/3
12/4
12/5
12/6
12/7
12/8
12/9
12/10
：Ueno Park

：Okachimachi, Ueno2：Hongo:In transit：Moving：Koishikawa botanic garden

Fig. 10 Example of diurnal habitations and times (crow #11).
Horizontal axis is time, color-coded by staying area. Vertical axis is date.

Movements of Crows in Urban Areas, Based on PHS Tracking

the non-breeding season.
The size of daily home ranges estimated by akernel method did not differ significantly between thebreeding and non-breeding seasons (Mann-Whitney
U5,7 = 10, p>0.05, two-tailed). The median size was
133,975 m2 in the breeding season and 1,469,987 m2
in the non-breeding season. The daily flight distancediffered significantly between the breeding andnon-breeding seasons (Mann-Whitney U8,10 = 6, p<0.01,

Fig. 11189

two-tailed). The median of the distance was 3132.2 m
in the breeding season and 7272.9 m in the
non-breeding season.
The continuous utilization rates of roosts (C)differed significantly between the breeding andnon-breeding seasons according to the Mann-Whitney
U-test (U8,9 = 12 p<0.05). Crows were more likely tochange their roosts in the non-breeding season than in
the breeding season.

Examples of exploratory flight. Daily flight paths of crow #6 (sedentary type) and #18 (migrant type 2).

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E. MORISHITA et al.

4. Discussion
Using PHS location devices, we obtained new
information about land use and movement patterns ofcrows in Tokyo and the surrounding area. We described the daily movement by dividing the areas
where the crows stayed into roosts, the morning habitations, and the diurnal habitations. Three movement
patterns emerged based on changes in this daily movement among these areas: roost areas, morning habitations, and diurnal habitations.
Land use of roost areas was not necessarily
separate from that used in daily movements. It has
been reported that large green spaces are often used bycrows as communal roosts in the non-breeding season(Institute for Nature Study, 2000). However, ourtracking data confirmed that 5 urban areas wereamong the 17 places observed being utilized by crows
as roosts in the non-breeding season. Moreover, one
crow (No.18) was observed roosting by itself in anarea with sparse vegetation. Thus crows do notnecessarily need a group of trees for roosting in the
non-breading season.
Exploratory movements were observed for someindividuals. In other words, some crows went to newareas from the area they had been staying in at thattime, and stayed there for a few hours or one night
during the tracking period. This behavior is similar
to intrusive behavior into an area by crows without
their own territories. The intruding crow visits anarea a few times and stays several hours a month at
first. Then it visits the site more frequently to establish itself as the territory owner (Kurosawa, 2000).
These brief exploratory visits are probably notintended to seek territorial area.
Crows of the sedentary type did not change roosts
during the tracking period, but went to same areas
regularly each day. There were many individuals
which showed this pattern during the breeding season.
We thought that one of the reasons was the environmental conditions, in the Ueno area. Since there areseveral restaurant districts, a lot of garbage is discharged by the road near Ueno Park. Sometimes wefound people feeding bread and other food to crows in
Ueno Park. So, crows in the Ueno area are provided
with abundant food. Moreover, since there areseveral small forests in Ueno Park and the surrounding area, crows are provided with rest sites and roostsites, too. As described above, the Ueno area has asufficient environmental capacity for crows. It isthought that the Ueno area is suitable for crows, sothey do not need to move.
Crows of the migrant types changed their roosts
and habitations, and there were many individuals
which showed this pattern during the non-breeding
season. The crows tracked by PHS were juveniles,
and they probably did not have their own territories.
It is known that non-breeding crows including thejuveniles change their roosts and range over a large

area during the non-breeding season (raven, C. corax,
Heinrich, 1988; american crow, C. brachyrhynchos,Stouffer et al., 1991; and carrion crow, C. corone,
Yoshida, 2003). Probably, our young crows showed
the same tendency.
The daily flight distances were longer in the
non-breeding season than in the breeding season.
This difference is associated with the fact that thecrows used the same roosts and habitations everyday
in the breeding season but changed them in the
non-breeding season. It is thought that these results
indicate a partial dispersal in the non-breeding season.
In this study, all of the crows tracked were
juveniles. We would like to study the movements ofadult crows in the near future. It will be interesting
to compare the movement patterns between adult andyoung crows.
On a technical note, there are two disadvantages to
PHS tracking. One is that the battery has a short life
(10 days on average). It is expected that PHS
transmitters will be developed whose batteries last ahalf or one year. If we have those devices, we will
be able to determine the seasonal movements of crows.
The second disadvantage is that the transmitter isslightly heavy for crows. The total weight of thetransmitter accounts for 4.2% of a crow’s body weighton average. For birds, the weight of a transmittershould be less than 4.0% of their body weight(Brander & Cochran, 1991). However, the effect of
our PHS on the crows was negligible as shown by
their pecking rates, and the device was useful in urban
areas. It is hoped that lighter PHS devices will be
developed in the near future.

Acknowledgements
Dr. I. Kobayashi, Dr. H. Hosaka, T. Ike and S.
Uematsu improved PHS transmitters for this study.
R. Egashira, C. Kurusu, D. Noma, H. Yoshida and H.
Ikoma helped to improve transmitters, capture crows
and track them. M. Yoshihara and K. Imai, T.
Amano, M. Eda, R. Kobayashi helped to capture
crows. H. Shimazaki provided his distance calculation program. T. Kurosawa helped to correct the
English draft. J. Pierre helped to capture crows andimprove the English of the draft. M. Fujita provided
helpful comments on this paper. We would like toexpress our deepest gratitude to these people.
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