PACKRAT (Neotoma) MIDDEN ANALYSIS:

First used in Quaternary Paleoecology introduced by Phillip Wells (Wells and Jorgensen, 1964), a zoologist doing vegetation reconnaissance on the Nevada Test Site. Packrats are widespread in arid western North America, and have been collected as far north as British Columbia. They are foliavores, primarily getting their water from the vegetation they eat. (Wells, 1976). Similar cave deposits left by other small mammals have been collected in caves of Australia, South America and the Near East.

MIDDEN MACROFOSSILS = f(R,S,H,D)

PRESERVATION:
middens are biogenic cave deposits
excellent!
protected by dried urine (amberat)
preserved only in rockshelters where aridity prevents dissolution


SELECTION:

Plant macrofossils are gathered in the local vegetation (30 - 100 m).
Different species of packrats prefer different kinds of plants

Neotoma cineria conifer leaves
Neotoma floridana broadleaved plants
Neotoma albigula cholla

HABITAT:
Cliffside vegetation different from veg. on surrounding lowlands; e.g., Juniperus (juniper) reaches lowest elevational in rocky habitats


DEPOSITION:
Deposition rate is unknown, middens may accumulate over years or centuries
Packrat middens contain fossils of different ages (Van Devender et al., 1985). Packrats incorporate older nest materials, and cracks and holes in midden permit mixing

METHODS

0.5-1 kg sample

selecting "Pleistocene" macrofossils has produced a bi-modal distribution (Webb, 1986).

1. Hand Specimen (Wells)
2. Disaggregation, screening & picking (Mehringer & Ferguson, 1969)

Macrofossil Keys
Comparison with reference collection for twigs, spines and leaves.

Abundance classes 1-5
Concentrations
Weight percentages

Tables
Diagrams

INTERPRETATION

Indicator Approach
presence of saguaro seeds means "hot and dry"
presence of pinyon pine means "cool"
presence of mesquite means "wet"

Oxygen and carbon isotopes from packrat middens

Density of stomata on conifer needles indicates atm. CO₂ conc. (Van De Water et al., 1994)

Pleistocene biogeography from packrat middens

Cole, 2002.

MIDDEN POLLEN TRANSPORT = f(A,V,B,F)
	Air Organ Pipe Cactus National Monument, 17% of the pollen in modern middens from plants not found in the local vegetation. Vegetation Trapped in hairs and sticky surfaces. Body Very abundant, body wash. Feces Ave. 174,354 grains gm-1 (Davis and Anderson, 1987)

OTHER BIOGENIC CAVE DEPOSITS Porcupine (Echinoprocta dorsatum) Betancourt et al., 1986 Hyrax (Procavia) urine, Louis Scott [link] Stick-nest Rat (Leporillus) urine, [link]