1. Monthly Analysis of Teal Ring- Recovery Data Diana Cole, Takis Besbeas, and Byron Morgan

2. Introduction Interested in modelling survival of Teal (Anas Crecca) Ring-Recovery Data available Standard analysis would be biased because –Teal are born in April –Ringing Year starts in August –Ringed in November, December or January

3. Standard Model (Annual / Annual)  1 – first year survival probability (annual survival)  a – adult survival probability (annual survival) – reporting probability j iNo. ringed1234 113210200 223 210 3426 2918 4447 38

4. Simulation Simulated data with 40 years of ringing and recovery, 200 animals ringed each year  1 = 0.3  a = 0.5 = 0.2 m b month animal born (in previous year) m r month animal ringed Parameters estimated using the standard yearly model. Simulation repeated 100 times.

5. Simulation Standard Model (Annual / Annual Model) 11 aa True Value0.30.50.2 mbmb mrmr meanbiasstdmeanbiasstdmeanbiasstd 13 (Aug)1 (Aug)0.300.000.0110.500.000.0170.200.000.004 12 (Jul)1 (Aug)0.310.010.0120.500.000.0180.200.000.005 9 (Apr)5 (Dec)0.530.230.0120.500.000.0140.200.000.004

6. Annual / Monthly Model  1,m – 1 st y. monthly survival probability  1,m 12 =  1  a,m – adult monthly survival probability  a,m 12 =  a – reporting probability model assumes ringed in December j iNo. ringed1234 113210200 223 210 3426 2918 4447 38

7. Simulation m b = 9 (Apr), m r = 5 (Dec) 11 aa Model 0.30.50.2 meanbiasstdmeanbiasstdmeanbiasstd annual / annual0.530.230.0120.500.000.0140.200.000.004 annual / monthly0.300.000.0170.500.000.0150.200.000.004

8. Simulation m b = 9, m r = 4 (52%), 5 (31%), 6 (17%) 11 aa Model 0.30.50.2 meanbiasstdmeanbiasstdmeanbiasstd annual / annual0.520.220.0290.500.000.0270.200.000.009 annual / monthly0.280.020.0550.500.000.0280.200.000.009

9. Monthly / Monthly Model Bird i, ringed in year y r, recovered in year y c, born in month m b = 9, ringed in month m r, recovered in month m c has probability Index (i)Ringyr (y r )Ringmo (m r )Recyr (y c )Recmo (m c ) 11959419606 219594 4 3 419645 419594 4

10. Simulation m b = 9, m r = 4 (50%), 5 (23%), 6 (17%) 11 aa Model 0.30.50.2 meanbiasstdmeanbiasstdmeanbiasstd annual / annual0.520.220.0290.500.000.0270.200.000.009 annual / monthly0.280.020.0550.500.000.0280.200.000.009 monthly / monthly0.300.000.0350.500.000.0250.200.000.009

11. Results model 11 aa annual/annual0.46 (0.037)0.55 (0.045)0.10 (0.004) annual/monthly0.18 (0.029)0.55 (0.045)0.10 (0.004) monthly/monthly0.11 (0.015)0.59 (0.046)0.10 (0.004)

12. Conclusion and Further Work If birds are not ringed soon after birth and / or the ringing year does not start when the birds are ringed, there will be bias in estimating first year survival. A monthly structure will remove this bias Survival does not have to be the same each month – e.g. lower survival in winter Teal data also include birds ringed as adults. The sex of the bird is known. Most of the returns were hunted (2% not hunted). Also census data on Teal. Plan to include this as part of an integrated statistical analysis.