Reproduction, Hormone Control, Hibernation, and Antlers

Determinant egg laying

Set number of eggs regardless of eggs in the nest

Indeterminate egg laying

Continues laying eggs when eggs are removed from nest

Vitellogenin

Gland by avian liver, induced by estrogens, binds calcium

Hormones involved in lactation

Oxytocin and prolactin

CL (Corpus Luteum)

Produces progesterone (P4) and maintains pregnancy

Hormones of the placenta

Estrogen and progesterone, related to LH stimulation

Induced ovulation

Stimulated to begin ovulation, different from spontaneous ovulation

Spontaneous ovulation

Ovulation occurs without any stimulus

Deer's implantation

Embryo doesn't implant until later in Midsummer

Birds and CL

Birds do not have a Corpus Luteum

Prolactin in doves and pigeons

Development of incubation patch, males feed young longer

Doves and pigeons laying eggs

Lay 2 eggs due to lower survival rate, crop milk is used to feed young

Techniques to look at reproductive effort

Testes size, sperm counts, ovarian analysis, fetal scales, placental scars, hormone analysis

Pregnancy Specific Protein B (PSPB)

Hormone used for pregnancy analysis

Principle of energy allocation

Trade-offs associated with reproduction and survival

Iteroparous

Reproductive strategy characterized by multiple reproductive cycles

Semelparous

Reproducing or breeding only once in a lifetime

Environmental variable for transitioning to pregnancy

Seasons affect food availability, which affects health factors for deer

Lipid reserves and reproduction in turkeys

Larger reserves result in larger clutch sizes, low reserves lead to higher predation

Clutch size and date of incubation

Large clutch + early initiation = high nesting success, small clutch + later initiation = high nesting success

Cubs nursing from fat mothers

Grow faster due to higher quality milk and longer nursing period

Delayed implantation and nutrition

Implantation depends on mom's body fat, below 20% implantation is unlikely

Adaptive fetal sex ratios

Fetal sex determined by environmental factors, such as breeding time

Offspring gender as maternal conditions improve

As conditions improve, more likely to have male offspring

Rose Petal Hypothesis

Alpha moms have overlapping home ranges of female offspring

Mourning doves and offspring

Lay 2 eggs due to slower growth and lower survival rate, males feed young longer

Hormonal control of feed intake, body weight, and metabolism

Regulation of thyroid hormones, hormones involved in thyroid function

Thyroid hormones T3 and T4

T4 is main one secreted, T3 is most active

Amino acid necessary for thyroid hormone production

Tyrosine

Physiological effects of thyroid quitting

Slow onset and long duration

Transport of T3 and T4 in the blood

Transported through blood by binding to plasma proteins

Thyroid hormone receptor location

Nucleus of the cell

Basal metabolic rate

Rate of metabolism while at rest

Effects of thyroid hormones on metabolic activity and growth

Increases metabolic activity, important for growth

Thyroid hormones during hibernation

Decrease in T3 and T4 compared to full food before denning

Heart rate measurement in bears

Implanted cardiac monitors using aseptic techniques

Seasonal variation in heart rate

Higher heart rate in spring/summer, lower heart rate in fall/winter

Behavioral changes in infected bats

Increased grooming during arousals from hibernation

Physiological changes in infected bats

Increased fat utilization, increased metabolism, increased CO2

Antler size determination

Genetics, nutrition, and age

Effect of castration on antler growth

Castration before antler growth prevents antler development

Hormones and antler growth

Role of T3, T4, cortisol, prolactin, GH, and IGF-1

Role of estrogen in antler growth

Estrogen acts as T and hardens antlers in caribou

Reindeer antlers

Both males and females have antlers, shed in late May or June

Role of winter foods for white-tailed deer

Sustain deer until food is more available

Reason for lowering metabolism in winter

To maintain body fat and stay warm

Difference between torpor and classical hibernation

Torpor is more easily aroused, hibernation requires more energy to rouse

Reasons for hibernation or deep torpor

Lack of food resources

Peak activity of bats after hibernation

Measured in December-March before sunset due to increased insect activity

Light sampling in bats

Bats fly to the edge of the cave to determine photoperiod

Advantages of staying deep in the cave

Safety from predators, warm climate

Advantages of getting close to the entrance

Check photoperiod, increase in insects/food