Synopsis 

The Portal Project is a long-term ecological study in southeastern Arizona.that has been monitoring small mammal community responses to climate and experimental manipulation of dominant rodent species since 1977  

Ecological Level

 Community

Biome: Desert

Location: Southeatern Arizona (Lat/Long)

Spatial Scale of data: Each plot is .25 ha. There are 24 plots.

Timespan: 1977-2002

Frequency: Monthly

Observational/Experimental: Experimental (but with long-term controls).
     Manipulation: Removal of kangaroo rats (Dipodomys spp.) and removal of all rodents.

Dataset Location:

Data collection summary: All plots are trapped for one night  each month. Each plot consists of 49 permanent trapping locations. Around the new moon, a sherman trap is placed at each stake. Data is collected for each animal that is caught. 

Data Collected: Species, gender, reproductive information, location caught, weight, hindfoot length, individual tag.

Issues:
1) "Monthly": While data collection is meant to be monthly, things happen. Trapping follows the new moon, so some years there are 13 sample periods because there were 13 new moons in a 12 month period. Weather, airline delays, etc, can cause sample periods to be missed, so some years will have less than 12 sample periods. The take home message: different years can have different sampling intensities. Do not simply sum all sample periods within a year and compare across years.