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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 • 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. females?
Reproduction & Survival • To understand data, need a quick primer on a few aspects of reproductive physiology Figs. 4 and 7 of Wildlife Techniques Manual
Reproduction & Survival • Placental scars – Formed when placenta tears out of the uterus during birth. Formed from a deciduous placenta • Insectivores • Lagomorphs • Rodents • Carnivores Fig. from JWM 60:432
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)
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
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)
Reproduction & Survival • Artiodactyls – Most work on wt deer • Table 1 from Kirkpatrick 1988
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)
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
Reproduction & Survival Table 4, Kirkpatrick 1988
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
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
Reproduction & Survival • Table 14 from Kirkpatrick 1988
Reproduction & Survival • Proportion of adults breeding - Carnivores • Fewer adult lynx breed if prey are scarce
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.
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
Reproduction & Survival • Table 2 from _____ (collared peccary reproduction)
Reproduction & Survival • Clutch Size • Arctic nesting geese Data from Ankney and Macinnes (1978)
Reproduction & Survival • Table 15 Kirkpatrick 1988
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
Reproduction & Survival • Litter Size – Artiodactyls • Nutrient restriction through breeding will cause a decline in litter size. Affect due to energy
Reproduction & Survival • Survival of young
