Ornithology Lecture 13

  • Research Opportunities

    • Importance of internships in environmental science and related fields

    • Internships may be unpaid, creating financial challenges

    • Option to participate in research as part of a course, earning credit and gaining experience

  • Migration Concepts

    • Migration Definition: Predictable cyclical movement between two or more non-overlapping home ranges.

    • Home Range: Geographic area necessary for an individual to perform its activities. Can differ for breeding and other tasks.

    • Distinction between migration and nomadism based on predictability of movements.

  • Reasons for Migration

    • Major energetic costs associated with migration; includes risks such as predation and extreme weather conditions.

    • Seasonal Variability: Changes in temperature and precipitation affect migration needs and survival rates, even in tropics.

    • Mortality during migration often linked to temperature and metabolic demands during harsh conditions.

  • Evolution of Migration

    • Studies show long-distance migration typically evolved from species shifting their wintering ranges southward rather than breeding ranges northward.

    • Non-migratory species often descended from migratory lineages.

  • Migration Strategies

    • Differences in migration distance categorized as short migrants (approx. 860 miles) and long migrants (up to 2,000 miles).

    • Survivorship Trade-offs: Shorter migrations may lead to higher winter mortality due to energy demands, whereas longer migrations increase risks during the journey but lower overall winter mortality.

    • Example: Red knots have distinct metabolic rates tied to migratory behavior; those that stay in harsh winters face higher mortality.

  • Reproductive Benefits

    • Short-distance migrants often see higher reproductive success despite potential risks during winter; compensate for lower survival with increased reproductive output.

    • Early arrivals to breeding grounds can secure optimal territories and mates.

  • Migration Patterns

    • Birds select migratory routes based on seasonal wind patterns and resource availability.

    • Distinction between stopover sites (brief stops) and staging areas (longer stays for refueling).

    • Adaptations seen in migratory strategies vary across species; individual behaviors also affect migration.

  • Factors Influencing Migration Timing

    • Ultimately controlled by ecological factors such as daylight (photo period) and related hormonal changes.

    • Proximal Controls: Hormonal changes prompt shifts in migratory behavior (e.g., migratory restlessness).

    • Dogglers vs. Procrastinators: Bird strategies to optimize migration based on timing and resource accumulation; both groups aim to arrive at breeding grounds synchronously.

  • Impact of Climate Change

    • Earlier insect emergence may decouple from bird migration schedules, leading to potential mismatches in breeding and food availability.

  • Light Pollution and Migration

    • Nighttime migration trends influenced by light pollution; 80% of birds migrate at night to avoid predators.

    • Numerous studies documenting how urban light impacts migratory paths and bird mortality, especially post-9/11.

    • Light Pollution Effects: Challenges with navigation and increased mortality due to direct and atmospheric light exposure.

  • Regional Migration Pathways

    • Importance of central flyways for migratory birds in North America.

    • Wind energy developments and light pollution significantly affect migration patterns and bird mortality.

  • Lab Preparation for Upcoming Field Work

    • Reminder for students to bring binoculars, prepare for wet weather, and anticipate potential adjustments in plans due to weather conditions.