Ornithology Lecture 15

Overview of Module

  • Focus on new material for the next unit (unit 4).

  • Test Reminder: Next test on Tuesday; material today is not part of the test.

Lab Information

  • Lab Location: Hardberger Park.

    • Meeting Time: 8 AM tomorrow.

    • Carpooling: Email instructor for arrangements.

    • Additional Notes: Bring binoculars.

    • Specific Meeting Area: Near Urban Ecology Center on Military Highway.

Grassland Restoration Area

  • Importance of Grassland Birds: Key for students interested in jobs related to surveys in Texas grasslands.

  • Potential Observations: Grassland birds and raptors due to wind development implications.

  • Wind Turbines: Significant impact on raptor mortality.

Introduction to Mating Systems and Parental Care

  • Mating Systems Overview: Focus on monogamy and polygamy, including definitions and subcategories.

  • Monogamy:

    • Definition: Pair bond between one male and one female.

    • Prevalence: 91% of bird species exhibit some form of monogamy.

    • Extra-Pair Copulation (EPC): Common in many species leading to social monogamy where pair bonds exist but may not result in exclusive offspring production.

Types of Mating Systems

  • Polygamy:

    • Definition: Umbrella term including various subtypes:

    • Polygyny: One male with multiple females (around 2% of species).

    • Polyandry: One female with multiple males (rare).

    • Promiscuity: Both sexes have multiple mating partners without established bonds.

Factors Influencing Mating Strategies

  • Resource Availability: Affects parental care decisions, especially under harsh conditions where one parent’s presence might not significantly contribute to offspring survival.

  • Young Types:

    • Precocial Young: Independent shortly after hatching (e.g., grouse).

    • Altricial Young: Require significant parental care post-hatching (e.g., raptors).

Parental Investment Game Theory

  • Game Theory Explanation:

    • Males and females weigh the benefits of staying versus leaving offspring based on survival probabilities and opportunities for future mating.

    • Variables include:

    • $W$: Eggs laid by females.

    • $P$: Probability of survival with varying parental presence.

    • $r$: Likelihood of re-mating opportunities for males.

Cooperative Displays and Altruism

  • Display Behavior in Males: Males often display for females to win mates, demonstrating competitive behaviors.

  • Cooperative Lekking: Males work together during displays to attract females, with subordinate males gaining future mating opportunities through successful displays.

  • Sexual Selection: Not just about reproductive success or offspring viability; focuses on obtaining mating opportunities through displays and other traits.

Parental Care Trends Across Animal Kingdom

  • Birds: General biparental care.

  • Mammals: Predominantly maternal care (females alone).

  • Fish: Often males provide care (e.g., in nesting situations).

Environmental Factors and Mating Systems

  • Facultative Polygamy: Environmental changes, such as climate change and resource variation, can alter mating systems.

  • Example: Red knots facing food availability issues affecting mating ratios, potentially leading to increased polygamous behavior.

Summary of Sexual Conflict and Mating Systems

  • Sexual Conflict: Males and females have differing reproductive strategies, often in competition due to differences in energy investment.

  • Key takeaway: Males may prioritize quantity (number of offspring), while females focus on quality (offspring survival and care).

  • Implications for Species Behavior: Environmental conditions shape mating strategies, with both cooperation and competition influencing parental care dynamics.