Demography, Reproduction, Diet and Crop Depredation in Three Species of Rodents in Natural and Irrigated Fields in Nigeria

<p>Rodent populations of <em>Arvicanthis, Mastomys</em> and <em>Tatera</em> were studied during July 1990 to August 1992 in both natural and irrigated savannah fields of northern Nigeria. <em>Tatera</em> was entirely absent from the irrigated fields. Irrigation enhanced higher rodent population densities in the magnitude of three to four times over densities in the natural field. <em>Arvicanthis</em> was the most abundant of the three species in both sites. <em>Tatera</em> was the least common in the natural site. Adult survival rates in <em>Arvicanthis</em> and <em>Tatera</em> were significantly higher than <em>Mastomys</em>. Survival rates of both adult and young differed between the wet and dry seasons, being lower during the peak rainy months of July-August. Monthly recruitment in the irrigated fields was nearly four-fold higher than that in the natural fields.</p> <p>In the natural fields all species showed strict seasonal breeding in tune with the rainy months (May-October), with <em>Arvicanthis</em> starting at the same time as the onset of the rains but a month or two ahead of <em>Mastomys</em> and <em>Tatera</em>. In contrast to reproduction in the natural fields, the breeding seasons in <em>Arvicanthis</em> and <em>Mastomys</em> in the irrigated fields were continuous.</p> <p>Seeds formed an important food group for all species in both sites during the rainy season. Mastomys (in both sites) and <em>Tatera</em> (in the natural site) maintained almost the same levels of seed intake throughout the year. The amount of seed intake by <em>Arvicanthis</em> was enhanced by irrigation. In both sites during the rainy periods, monocots and insects made up the second and third most important food groups by mass of the diet intake of the species.</p> <p>The damage and yield loss caused by rodents in cereal crops in irrigated savannah fields was investigated. The high level of yield loss in wheat, compared to low and moderate levels in rice (grown for the most part during the rains), was probably a result of the greater depredation rate on the wheat, grown by irrigation during the dry season when other rodent food sources were less abundant.</p> <p>By the absence of <em>Tatera</em> in the irrigated fields this study provides evidence that the responses of African rodents to irrigation differed among the species. This study also demonstrates the opportunistic tendency of the rodents to exploit new, highly productive habitats as seen in their continuous reproduction, higher population densities and greater depredation of seeds and cereals in the irrigated fields. <em>Arvicanthis</em>, <em>Mastomys</em> and <em>Tatera</em> stand indicted as crop pests in both rainfed and irrigated agriculture.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biological Sciences

Year dc:date.available

1995

Author dc:creator

• Rabiu, Safianu

Contributors dc:contributor

• Robert K. Rose
• Lytton J. Musselman
• Joseph Rule

• Arvicanthis
• Mastomys
• Tatera
• Wheat rice
• Agronomy and Crop Sciences
• Ecology and Evolutionary Biology
• Zoology

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Repository record dc:identifier

https://digitalcommons.odu.edu/biology_etds/70

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:biology_etds-1074