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Estimación de Supervivencia

Estimación de Supervivencia. Recuentos sucesivos Pobl. cerradas Tablas de Vida H & V Identificación de individuos Identificación de edades Captura/Marcado/Recaptura múltiple Pobl. cerradas – Pobl. abiertas. Closed populations.

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Estimación de Supervivencia

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  1. Estimación de Supervivencia Recuentos sucesivos Pobl. cerradas Tablas de Vida H & V Identificación de individuos Identificación de edades Captura/Marcado/Recaptura múltiple Pobl. cerradas – Pobl. abiertas

  2. Closed populations No individuals enter or leave the population between surveys Survey 2 Survey 1

  3. Open populations Individuals enter or leave the population between surveys Survey 2 Survey 1

  4. What makes a population closed? • Dispersal barriers • Philopatry • Large surveyed area • Slow reproductive/death rate • Short time between surveys

  5. Petersen method: Closed population Survey 1: Survey 2: Catch several animals Catch C animals Count recaptures (R) Mark all M animals Return animals to population Return animals to population

  6. Survey 2: Survey 1: M = 12 C = 15 R = 4

  7. M = R N C N = M C R What is the total population size (N)? Note that the proportion marked in the population equals the proportion marked in the 2nd sample M = 12 C = 15 R = 4

  8. N = 13 * 16 5 -1 What is the total population size (N)? Note that the proportion marked in the population equals the proportion marked in the 2nd sample N = (M+1) (C+1) (R+1) -1 M = 12 C = 15 R = 4

  9. When would Petersen give you a bad estimate? • Population not closed • Marked animals likely to be re-trapped • Marked animals likely to die • Marks fall off

  10. Survey 2 Survey 3 Survey 4 Survey 5 Schnabel method: closed population Survey 1 Essentially, Petersen estimates on multiple surveys

  11. Survey t: Catch Ct animals Record Rt recaptures Mark Ut unmarked animals Return animals to population Schnabel method: closed population

  12. Schnabel method: closed population Survey t: Catch Ct animals What’s the relationship between Ct, Rt, and Ut ? Record Rt recaptures Mark Ut unmarked animals Ct = Rt + Ut Return animals to population

  13. Schnabel method: example 0 48

  14. Schnabel method: example 0 48 Σ = 2060 Σ = 22

  15. Schnabel method: example N = Σ (Ct Mt) = 2060 = 94 Σ Rt 22 0 48 Σ = 2060 Σ = 22

  16. Mark recapture lectures • Petersen method • Schnabel method • Schumacher-Eschmeyer • Jolly Seber Closed population Open population

  17. Captura/Marcado/Recaptura múltiple Población cerrada o abierta (emigración sin retorno) Identificación individual sin errores Marcas fáciles de identificar Muestra y mezcla aleatoria de individuos capturados Heterogeneidad Respuesta a la trampa (adicción/áversión) Marcas imperdibles y fáciles de detectar

  18. Captura/Marcado/Recaptura múltiple En gral. requiere alta capturabilidad Se obtiene Supervivencia y Capturabilidad (en ambos casos, uno o más parámetros) Se obtienen los Errores Estándar de los parámetros (consejos y estrategias) Se puede obtener Abundancia poblacional (precauciones)

  19. Diseño robusto de captura-recaptura Períodos Primarios Períodos secundarios 1 2 …. K 1 2… t 1 2… t 1 2… t La población se considera cerrada entre períodos secundarios de un mismo período primario: muy buen estimador de tamaño poblacional para el período primario Buen estimador de supervivencia entre períodos primarios haciendo un pool de sus períodos secundarios

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