Models for Population Growth Curves

Table 1

Comparison of the generalized logistic (1) with the corresponding difference equation (2) and the ordinary logistic (6) compared with the corresponding difference equation (7). Numbers in square brackets refer to references and other numbers are GPDD numbers. Values given are residual mean squares from the fits.

Source	Generalized logistic	Difference equation	Ratio	Logistic	Difference equation	Ratio
Red deer 6585	2.16	2.47	1.14	3.1	2.8	0.90
Gray fox 319	283	591	2.09	378.2	566.7	1.50
Gray fox 342	1311	1440	1.10	1254	1399	1.12
Coyote 263	2528	2729	1.08	2451	2681	1.09
Gray seals [1]	56.83	93.2	1.64	65.93	90.88	1.38
Bison [2]	5.81	7.86	1.35	5.64	7.81	1.38
Macaque 6068	1.11	1.32	1.19	1.45	1.43	0.99
Beaver 151	15960	16490	1.03	15850	16410	1.04
Beaver 156	40960	43800	1.07	43400	44070	1.02
Elephant seals [3]	48.61	63.44	1.31	50.06	62.79	1.25
Seneca deer [4]	29.93	50.78	1.70	28.99	50.44	1.74
Badger 78	375	453	1.21	372.5	438.8	1.18
Gentoo penguins (Fraser pers. comm.).	61.19	113.2	1.85	57.88	108.6	1.88
Polar bear 143	89.9	68.1	0.76	95.09	67.49	0.71
Coyote 247	308	380	1.23	335.7	362.4	1.08
Gray fox 328	549.3	901.3	1.64	526.1	850.1	1.62
Marten 9695	17020	22010	1.29	16630	22390	1.35
Squirrel 9699	347100	393400	1.13	339100	398500	1.18
Gray fox 334	3383	3332	0.98	3280	3155	0.96
Camargue horses [5]	0.58	1	1.72	1.42	1.74	1.23
Argentine horses [6]	5.01	8.04	1.60	5.38	7.8	1.45
Przewalski's horses [5, 7]	0.89	1.39	1.56	1.23	1.47	1.20
Red kite [8]	3.27	4.56	1.39	3.2	4.46	1.39
Medians and Mean Ratios	89.9	113.2	1.35	95.09	108.6	1.20