Table 1.

Temporal trends in relative abundance before and after the flood

Species	Preflood RA (mean ± SD)	Preflood OLS regression	r2	Postflood RA (mean ± SD)		t	P value
				Observed	Expected
Preflood since 1978
D. merriami	0.48 ± 0.12	y = 0.0062x + 0.340	0.39	0.25 ± 0.08	0.66 ± 0.02	−14.2	<0.001
D. ordii	0.12 ± 0.05	y = 0.0012x + 0.089	0.10	0.11 ± 0.04	0.15 ± 0.00	−2.56	0.034
C. baileyi	0.05 ± 0.03	y = 0.0094x − 0.332	0.65	0.22 ± 0.05	0.13 ± 0.03	5.78	<0.001
C. penicillatus	0.04 ± 0.05	y = 0.0022x − 0.010	0.34	0.26 ± 0.07	0.10 ± 0.01	8.94	<0.001
Preflood since 1995
D. merriami	0.49 ± 0.06	y = 0.0106x + 0.062	0.16	0.25 ± 0.08	0.62 ± 0.04	−11.6	<0.001
D. ordii	0.13 ± 0.03	y = 0.0068x − 0.150	0.24	0.11 ± 0.04	0.20 ± 0.03	−5.35	<0.001
C. baileyi	0.05 ± 0.03	y = 0.0094x − 0.332	0.65	0.22 ± 0.05	0.13 ± 0.03	5.78	<0.001
C. penicillatus	0.11 ± 0.06	y = 0.0143x + 0.692	0.35	0.26 ± 0.07	0.01 ± 0.02	15.36	<0.001

Shown are data from the four most common rodent species from before the flood [1978–1999 or 1995–1999 (after C. baileyicolonization)] compared with observed and expected trends after the event (1999–2005). Trends were characterized by using OLS regression (all P values < 0.05), and differences between Observed and Expected were tested with paired ttests on arcsine-transformed data. RA, relative abundance.