**3. Cause of infestation of black rats**

It is the structure of the building that is the cause of heavy infestations by black rats. Big buildings in the centers of big cities usually have several catering establishments and these provide the food for black rats. Such buildings, with their network of hidden pipes and false ceilings, also provide ideal habitats and nesting places for the rats. Warmth from cooking in the catering establishments and from electrical equipment being used in such buildings also probably supply sufficient heat for all-season breeding.

**3**

**Figure 3.**

*Prologue: Commensal Rodent Problems Across the Globe DOI: http://dx.doi.org/10.5772/intechopen.95828*

to control rats [21, 22].

busy streets.

**4. Norway rats in busy street**

buildings. Big buildings of 3,000 m<sup>2</sup>

**5. Conservation of island ecosystem**

*Garbage in plastic bags along roadside, and a Norway rat attacking such bags.*

Environment to conserve island ecosystems.

Another cause of heavy infestation is the difficulty experienced in controlling black rats. Most PCOs had long used first generation anticoagulants, and as a result, black rats acquired resistance to the rodenticide [19]; black rats are also extremely cautious of baits. Moreover, catering establishments disapprove of rodenticide operations because of difficult-to-manage rat carcasses that result. PCOs have therefore to use glue boards and of these black rats are also cautious. Today rat proofing techniques are common in PCOs, but long-term rat-proofing of such buildings is sometimes difficult because of the frequent remodeling of the interiors of these establishments. The cause of the increase of black rats in residential areas from the mid-1990s is unknown, but I suppose that an increase of aged population living alone is one of the factors. Single families composed of people 65 years old or more tended to increase rapidly in the 1990s in Japan [20]. It is sometimes difficult for such people to rearrange rubbish and garbage around them

The removal system of garbage is different between big buildings and small

Since the early-2000s eradication campaigns of rodents have been conducted in islands such as Yururi-Moyururi in Hokkaido, northern Japan, and the Ogasawara Islands, southern Japan [14, 15]. These projects were supported by the Ministry of

as stores, offices and hotels are regulated by the Building Standard Act. In these buildings, garbage is treated by building management companies. On the other hand, small buildings are out of regulation, and garbage in these buildings is usually kept in plastic bags and put along roadside (**Figure 3**). Accordingly, small buildings supply Norway rats with food sources, and the rats have become big problems in

or more in total floors occupied by tenants such

*Prologue: Commensal Rodent Problems Across the Globe DOI: http://dx.doi.org/10.5772/intechopen.95828*

*Rodents*

**Figure 1.**

*Metropolis during control campaigns [16, 17].*

**2**

**Figure 2.**

**3. Cause of infestation of black rats**

*Shinjuku, Yokohama, and Nagoya [9–11].*

It is the structure of the building that is the cause of heavy infestations by black rats. Big buildings in the centers of big cities usually have several catering establishments and these provide the food for black rats. Such buildings, with their network of hidden pipes and false ceilings, also provide ideal habitats and nesting places for the rats. Warmth from cooking in the catering establishments and from electrical equipment being used

*Yearly changes in percentage of basal area of buildings >10 m high in commercial districts in Sapporo, Sendai,* 

*Changes in species composition of commensal rats collected with snap traps in Osaka city and the Tokyo* 

in such buildings also probably supply sufficient heat for all-season breeding.

Another cause of heavy infestation is the difficulty experienced in controlling black rats. Most PCOs had long used first generation anticoagulants, and as a result, black rats acquired resistance to the rodenticide [19]; black rats are also extremely cautious of baits. Moreover, catering establishments disapprove of rodenticide operations because of difficult-to-manage rat carcasses that result. PCOs have therefore to use glue boards and of these black rats are also cautious. Today rat proofing techniques are common in PCOs, but long-term rat-proofing of such buildings is sometimes difficult because of the frequent remodeling of the interiors of these establishments. The cause of the increase of black rats in residential areas from the mid-1990s is unknown, but I suppose that an increase of aged population living alone is one of the factors. Single families composed of people 65 years old or more tended to increase rapidly in the 1990s in Japan [20]. It is sometimes difficult for such people to rearrange rubbish and garbage around them to control rats [21, 22].
