Fig. 4. Observed and expected numbers of female pups born at the Isle of May in (A) 1990; (B) 1991; (C) 1992; (D) 1993; (E) 1994 and (F) 1997. Cumulative number of re-sights of individually marked females breeding is shown by a narrow dotted line. Number of individually marked females known to be alive is shown by a bold dotted line. Expected numbers of pups alive and tagged are shown by dashed or solid lines using different first year survival rates (phi) and tag loss (loss) rates as indicated.