In this special issue of the Global Environmental Research, we will show the present state and mechanisms of some of the conflicts between crows and humans in urban areas. In the first article, Mutsuyuki Ueta and his colleagues describe the population trends of crows in Tokyo. They collected data on the population and distribution of jungle crows (Corvus macrorhynchos) and analyzed the possible factors affecting trends. Their findings show that crows started to increase when household garbage began to be disposed in plastic bags for pickup, but not when the amount of food scraps in the garbage reached its peak. The next two articles focus on crow problems, such as food scraps being scattered by crows at garbage sites, and discuss some effective management measures to reduce the problems. Reiko Kurosawa and her colleagues worked in the greater Tokyo area, and Makiko Takenaka in Sapporo, northern Japan.

　The next three articles cover specific crow behaviors. Hiroyoshi Higuchi and his co-workers studied the behavior of crows that stole soap bars from a kindergarten. They traced the soap bars by inserting transmitters into the bars, and studied why the crows took the soap and what they did with it. Hiroyoshi Higuchi discusses another strange behavior of crows—stealing candles from shrines, which may be linked to fire outbreaks. He suggests that a total of seven fires that have occurred near shrines in the last few years in Kyoto are likely the work of crows. Higuchi and Emiko Morishita report on another dangerous behavior of crows—placing stones on railroad tracks—and show that the behavior is associated with their hoarding habits, as in the cases of soap bars and candles.

　The next two articles are about the spatial distribution and movements of crows in urban areas. Kazuhiro Katoh and Takashi Nakamura studied the distribution of crows through observations in open spaces such as parks and cemeteries. They clarify the role of such open spaces in crows' daily flying activity. Morishita and Higuchi report their results of tracking the local movements of crows using a personal handy phone system (PHS). They show the daily movement patterns and the differences among individuals and between seasons. This is the first report in Japan on the detailed movements of crows in urban areas. The ninth article describes the food habits of crows, revealed by analysis of pellets and feces and through direct observation. It shows that crows exploit a wide variety of foods in response to temporal and seasonal availability in both urban and rural areas, and suggests 130 that if food scraps in urban areas could be reduced, a great proportion of the food currently available to crows would be lost.

　In the final article, Masaki Okuyama reports on governments’ measures to deal with crows, based on his experiences as a government officer in charge of the issue. He emphasizes the importance of cooperation among related sections within a government and among neighboring governments, and states that efforts of Japan’s Ministry of the Environment are aimed at enhancing the flow of information and awareness among all the parties concerned.

　All studies except the last one were conducted independently from each other and from governments. As a result, these studies are not systematically connected to each other, and some important information on population dynamics and other topics is absent from this issue. But I believe that this collection of articles will be useful when considering the management of crows and reduction of conflicts between crows and humans. I also hope that this issue will encourage wildlife biologists and government officers to conduct further studies on the relevant subjects.

　We conducted a literature survey on changes in population and distribution of jungle crows (Corvus macrorhynchos) in Tokyo and analyzed possible factors affecting the changes. The number of crows in five major roosts in central Tokyo drastically increased in the mid-1980s through the mid-1990s, leveling off and/or slightly decreasing afterwards. In 2001 and 2002, 33 crow roost sites were observed in Tokyo. Although the histories of these minor roosts are poorly known, some of them were established, or increased in roosting numbers, in the 1990s. Therefore, the increase in crow population in Tokyo has not stopped but entered a different phase.

　The period during which the crows started to increase was synchronous with that when domestic garbage began to be disposed in plastic bags for pickup, but not when the amount of food scraps in the garbage reached its peak. Considering that buckets with tight lids prevent crows from scavenging the food scraps inside the container, but that flimsy plastic bags allow crows easy access to the food scraps, these results suggests that the population of crows in Tokyo was more affected by the change in availability of food scraps than their quantity.

　The distribution of breeding jungle crows increased at urban sites in the 1990s and decreased in woodlands compared to the 1970s. Jungle crows came to breed in areas with less vegetation cover and higher urbanization rates, which led to the increase in distribution.

　Complaints by the citizens against crows increased during the 1990s in Tokyo, mostly because crows’ scavenging caused a mess at communal garbage collection stations. We conducted a few pilot studies on counter-scavenging measures and assessed those of local governments so as to find possible solutions to conflicts between man and crows in urbanized areas. Assessment of social aspects was done by questionnaires to the citizens, and field surveys on the actual state of crows and garbage.

　The citizens’ complaints had biases. Their value, therefore, was limited as an indication of the existence of conflicts. The field surveys revealed that crows occurred at higher densities in central Tokyo than in the suburbs, contrary to conventional concepts. Compiling the results of the complaints and analyzing the field surveys were two indispensable procedures to seek for possible solutions.

　The assessments of the pilot projects showed three realistic approaches to countering the scavenging of garbage. Reducing the amount of food scraps was the only solution that would work against all types of scavengers. The second option was the temporal segregation of food scraps from diurnal scavengers (midnight/early morning garbage collection and time-specific collection). Spatial segregation of garbage from scavengers by protective nets and containers had variable effects.

　The responses to the questionnaires showed that where scavenging by crows decreased, so did people’s negative feelings towards crows. Therefore, we suggest that counter-scavenging measures could solve a major part of the crow-man conflict in urbanized areas.

　Crows in urban and residential areas have caused friction and problems in Sapporo, as in other urban areas in and out of Japan (Ministry of Environment, 2001; Vuorisalo et al., 2003; Gorenzel et al., 2002). The problems include garbage depots messed up by crows, attacks on passers-by particularly near nests, and damage to fruits and crops. Crows are often regarded as a nuisance and arouse feelings of fear or resentment often based on false assumptions among some citizens. This results in frequent claims from the citizens that the city must eradicate as many crows as possible. However, the management and control of crow populations, if necessary, should be based on correct data and observation of their ecology, behavior, distribution and abundance. These data may also be used to improvise measures to drive crows away effectively from undesirable areas. This paper describes the status of two common crow species, Corvus corone and C. macrorhyncus, in the Sapporo area in the winter of 2002 and 2003. The results of a roost site survey were compared with some of the results obtained in between 1991 and 2001, which proved that the crow population stayed fairly constant between those years. Roadside censuses revealed that the temporal and spatial distributions of these two species varied considerably from late autumn to winter. Garbage depot surveys illustrated clearly that protecting garbage depots was an effective method for curbing the number of crows in the neighborhood. Municipal and residents’ efforts are also described, which are aimed at finding better ways of coexisting with crows rather than haphazardly eliminating them. Though still at an early stage, the city’s project to understand the ecology of crows as wild bird species is expected to be helpful in terms of both raising citizens’ awareness of the advantages of peaceful coexistence with crows and devising methods to curb the numbers in undesirable areas.

　Many soap bars have been carried by jungle crows from a Kindergarten in Chiba, central Japan. We traced the soap bars from the kindergarten by inserting transmitters into the bars, and studied why the crows took the soap and what they did with it. All the bars carried were found within a radius of 110 m of the kindergarten. Most of them were hidden in fallen leaves on the forest floor. Some of the bars were moved again to other sites, and were stored again. All the bars traced showed increasing amounts of damage, suggesting that the crows ate some of the soap each day. Visual observations and video images suggest that only a few crow individuals were involved in this soap carrying and storing. The high number of bars taken suggests that soap has become a favorite food for the crows.

　Crows carry candles from exterior holders at Fushimi-Inari shrine, Kyoto, Japan, and may be causing field fires. This behavior was studied through fieldwork that included making video recordings. Jungle crows carried the candles to an area within a 50-100 m radius of the study site, which had a candle holder. After stealing the candle, the crows perched in a nearby tree gnawing on the candle held in one or both feet. Then, the crows carried the candle into the forest and hid it in debris on the forest floor. No clear evidence could be obtained on how field fires were occurring, but we can speculate about the possibility of the candle still being alight when hidden by crows and so igniting the material used to cover it.

　In Yokohama, central Japan, a carrion crow laid stones on railroad tracks when hoarding bread or retrieving it to eat. The crow picked up stones on either occasion. When the stones were heavy or awkward for the crow to hold with its beak, the crow laid the stones on the tracks, perhaps intending then to take a more comfortable grip on the stone. The crow also put stones on the tracks to remove breadcrumbs from its beak. The suitable height and flat surface of the tracks probably induced the crow to lay the stones on the tracks. When the crow laid stones on the tracks, it often picked them up again and carried them away. On rare occasions, however, the crow left stones on the tracks, causing the trains to make emergency stops.

　Jungle crows (Corvus macrorhynchos) have increased in number in urban areas across Japan, creating various kinds of problems. In the present study, jungle crows were counted at 33 study plots located in large open spaces (>10 ha) in central Tokyo to clarify the role of urban open spaces in crows' daily flying. Three types of open spaces were recognized: ones used mainly for post-feeding rest, ones used for further foraging and/or temporary rest throughout the daytime and ones used as roosting sites. Open spaces where people fed doves or homeless cats tended to be categorized as the second type, probably because crows stayed there to get food provided for doves or cats. In the open spaces of the first two types the number of crows correlated positively with tree coverage, indicating the importance of trees as components of crows' day-time habitat.

　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 the surrounding 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.

 An animal species’ diet constitutes the basic ecology of that species and is indispensable for understanding its population dynamics. As jungle crows have increased in the urban areas of Tokyo, conflicts between humans and crows have increased. Since highly urbanized areas are poor in natural food resources, it is possible that jungle crows depend heavily on human-related food in Tokyo. We have, therefore, determined their diet and compared the results with those of other regions, taking steps firstly, to assess the reliability of information from pellets, feces and direct observations of feeding crows.

 Jungle crows exploit a wide variety of food in response to temporal and seasonal availability in urban as well as rural areas. Their winter diet consists primarily of plant matter, suggesting that they retain their original food habit of eating fruits and berries of trees and shrubs, even at a heavily urbanized site. The proportion of food scraps in their diet was similar to that of animal matter in our study, suggesting an unusually ample availability of anthropogenic food sources in this city. If food scraps in Tokyo could be reduced, a great proportion of the food currently available to the crows would be lost, driving down the carrying capacity. We suggest ecological studies be conducted before making some action plans to solve wildlife issues.

　Conflicts concerning the coexistence of crows and humans and administrative efforts for combating these problems have a long history. Generally, the practical aspects of adopting administrative measures against crow issues rest with the local government. If capture is necessary, it should be conducted under guidelines of the Wildlife Protection and Hunting Law. There is a need, however maximize preventive efforts before resorting to capture programs, and these are being conducted by each local government section for agricultural promotion or waste management. Recently, conflicts between humans and crows have increased in urban areas and many local governments have been suffering from these problems. In Tokyo, the government has launched an urgent project, including aggressive capture programs, to decrease the population of crows in response to rising complaints from urban residents about crows associated with their increase in the city.

　The Ministry of the Environment made educational and promotional efforts in order to reduce the trouble between crows and city dwellers. It is expected that with regard to important procedures leading to solving the conflict between man and crows, cooperation among related sections within a government and/or among neighboring governments will be essential. Promotional efforts of the Ministry of the Environment are aimed at enhancing the flow of information and wisdom among all the parties concerned.