Capture rate and reproductive patterns of Norway rats Rattus norvegicus (Muridae: Rodentia) in a poultry farm in México City

Abstract

WE DESCRIBE SOME POPULATION AND REPRODUCTIVE CHARACTERISTICS OF NORWAY RATS, RATTUS NORVEGICUS (MURIDAE) IN A POULTRY FARM FROM SOUTHERN MEXICO CITY IN WHICH 10000 HENS ARE KEPT. MONTHLY TRAPPING USING 100 TRAPS WAS CONDUCTED FROM FEBRURY 1988 TO JANURY 1989. SIX HUNDED AND FIFTY SIX INDIVIDUALS WERE CAUGHT FROM FEBRUARY TO APRIL 1988, PEAKING AT 77 INDIVIDUALS. A SIGNIFICANT DECREASE IN THE NUMBER OF TRAPPED INDIVIDUALS WAS OBSERVED FROM MAY TO SEPTEMBER, REACHING A LOW OF 10 INDIVIDUALS, AND FOLLOWED BY A MODERATE INCREASE. PREGNANT FEMALES WERE OBSERVED THOUGHOUT THE STUDY, PEAKING MOSTLY DURING THE DRY SEASON (MARCH TO MAY). TWENTY SEVEN PERCENT OF ADULT FEMALES CAUGHTS THOUGHOUT THE STUDY WERE LACTATING. THE AVERAGE NUMBER OF EMBRYOS PER FEMALE WAS 7. 97 0.77, RANGING FROM 1 TO 15 (N=108).