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Reproduction & Survival. Reproduction & Survival. Nutrition is of interest to ecologists and managers because it has the potential to affect demographic processes Many stages of reproductive cycle may be affected by nutrition. Reproduction & Survival. Fig. 1 Kirkpatrick 1988. males vs.

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Reproduction & Survival

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Reproduction & Survival


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Reproduction & Survival

  • Nutrition is of interest to ecologists and managers because it has the potential to affect demographic processes

  • Many stages of reproductive cycle may be affected by nutrition


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Reproduction & Survival

  • Fig. 1 Kirkpatrick 1988

males vs.

females?


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Reproduction & Survival

  • To understand data, need a quick primer on a few aspects of reproductive physiology

Figs. 4 and 7 of Wildlife

Techniques Manual


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Reproduction & Survival

  • Placental scars – Formed when placenta tears out of the uterus during birth. Formed from a deciduous placenta

    • Insectivores

    • Lagomorphs

    • Rodents

    • CarnivoresFig. from JWM 60:432


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Reproduction & Survival

  • Age at first reproduction

    • Young animals sensitive to nutritional condition

  • Most birds, breeding by yearlings the norm

  • Waterfowl and raptors

    • Some evidence puberty advanced by nutrition

  • Puberty could change in long lived species

  • Some evidence of earlier puberty in small mammals

  • Lagomorphs / squirrels – Earlier puberty, esp. if adults breed earlier in year. Young breed later that same year (4-9 months old)


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Reproduction & Survival

  • Carnivores

    • Lynx: Hare high  99% yearling lynx breed

      low  5% yearling lynx breed

      see Table 4 from Mowat et al. 1996. JWM 60


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Reproduction & Survival

  • Carnivores

    • Lynx: Hare high  99% yearling lynx breed

      low  5% yearling lynx breed

    • Fox: yearlings seem to breed every year

    • Coyotes: Abundant prey  65-83% yrl breed

      Scarce prey  0-23% yrl breed

    • Bears: Good food conditions can advance puberty 3-5 years (e.g. 3 years old vs. 8)


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Reproduction & Survival

  • Artiodactyls – Most work on wt deer

  • Table 1 from Kirkpatrick 1988


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Reproduction & Survival

  • White-tailed deer (Abler et al. 1976)

    • 9 of 11 fawns on high energy diet cycled

    • 0 of 8 fawns on low energy diet cycled

    • protein in diet (9.6 vs. 18.2) had no effect

    • body weight of cycling and non-cycling fawns not dramatically different

Table 26 from Elk of North America (1982)


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Reproduction & Survival

  • Length of the breeding season

    • For species that can reproduce >1 time/yr, breeding season length may vary

    • Many small mammals will have >1 litter/yr if nutrients are sufficient

    • Quail in S. Texas will nest >1 if conditions are good (not clear that nutrition is driving force)

    • Snowshoe hares w/ feed had up to 4 litters/yr. Hares w/o feed had ≤3. % hares w/ 2 and 3 litters greater in areas w/ feed


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Reproduction & Survival

Table 4, Kirkpatrick 1988


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Reproduction & Survival

  • Proportion of adults breeding

    • In waterfowl, galliforms, and raptors, fewer adults breed when food resources are poor

    • Have been manipulative studies done with raptors and turkeys


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Reproduction & Survival

  • Proportion of adults breeding

    • In small mammals, can have fewer adults breed when nutrition is poor, but not consistent

Fig 7 from Kirkpatrick 1988


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Reproduction & Survival

  • Table 14 from Kirkpatrick 1988


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Reproduction & Survival


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Reproduction & Survival

  • Proportion of adults breeding - Carnivores

    • Fewer adult lynx breed if prey are scarce


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Reproduction & Survival

  • Proportion of adults breeding - Carnivores

    • Bears are very sensitive to food resources. Why would bears be particularly sensitive?

    • 33, 44, and 59% adult black bears had cubs following years of scarce, moderate, and abundant mast crops

    • In good habitats, adult black bears produce every other year. In poor habitats, produce every 3-4 years.


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Reproduction & Survival

  • Proportion of adults breeding - Carnivores

    • Fox and coyotes ovulate every year

    • Ovum may not implant if female is in poor condition

  • Artiodactyls

    • Cycling in adult females can be altered if in poor condition


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Reproduction & Survival

  • Table 2 from _____ (collared peccary reproduction)


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Reproduction & Survival

  • Clutch Size

    • Arctic nesting geese

Data from Ankney

and Macinnes (1978)


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Reproduction & Survival

  • Table 15 Kirkpatrick 1988


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Reproduction & Survival

  • Litter Size - Small mammals

    • Effect found in some studies but not all

    • Litter size affected by nutrition in snowshoe hares, but not necessarily in cottontails

  • Carnivores

    • Litter size varies with prey abundance

    • Bears have 1-2 cubs in poor habitat conditions and 3-4 in good conditions


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Reproduction & Survival


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Reproduction & Survival

  • Litter Size – Artiodactyls

    • Nutrient restriction through breeding will cause a decline in litter size. Affect due to energy


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Reproduction & Survival

  • Survival of young


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Reproduction & Survival


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