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Estimación de Supervivencia

This document explores estimation techniques for closed and open populations, focusing on capture/mark/recapture (CMR) methods such as the Petersen and Schnabel techniques. It explains how to identify individuals, their ages, and how to determine total population size (N) while considering key factors for population closure like dispersal barriers and reproductive rates. The text highlights potential errors in estimating populations and offers strategies for effective CMR design to assess population abundance and survival parameters.

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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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