Ornithology Ex3 P2

Where in the world are bird species found, and why?

• Birds occur in all major biomes because they are highly adaptable.

• Major biomes where birds are found:

  • Tropical/Subtropical forests: highest diversity, stable climate.

  • Temperate biomes: strong seasonality, many migratory species.

  • Dry biomes (grasslands, deserts): species adapted to heat/drought.

  • Polar/Montane biomes: cold-adapted, specialized species.

  • Aquatic biomes: waterbirds using lakes, rivers, coasts, oceans.

• Distribution depends on climate, habitat availability, and evolutionary history.

What is a biome?

A biome is a large ecological community defined by:

• Climate (temperature, rainfall),

• Geography, and

• Biogeographic history.
  It contains characteristic plants, animals, and ecological interactions.

What is an ecotone?

An ecotone is a transition zone between two habitats or biomes.

• Bird communities turn over here because species change with habitat.

• Often has higher diversity because species from both habitats overlap.

What are life zones and what is elevational zonation?

• Life zone: a region or elevational band characterized by a unique set of plant and animal species.

• Elevational Zonation: Related bird species occur in different elevation bands on mountains, with species changing as you move up or down the slope.

  Driven by:

  • Habitat changes with elevation

  • Climate shifts (temperature, moisture, oxygen)

  • Competition between species

What is species richness?

Species richness = the number of different species present in a location, community, or region.

What are alpha, beta, and gamma diversity?

Alpha diversity:
The number of species found within a single habitat or local site.
→ Measures local diversity at one point/location.

Beta diversity:
The difference in species composition between habitats, shown by the increase in species as you sample more sites.
→ Measures turnover — how much species change from habitat A → B → C.

Gamma diversity:
The total number of species across all habitats within a broad region.
→ Measures regional diversity (all alpha sites combined).

What is a species accumulation curve?

a graph that plots the number of new species discovered over a given sampling effort

• Y-axis: number of species detected

• X-axis: sampling effort (surveys, individuals counted)
  Used to see whether more sampling would reveal more species or if the community is well-sampled.

What are ecological guilds? Give examples.

A guild is a group of species that use the same resources or feed in similar ways.
Examples:

• Grass seed eaters: Indigo Bunting & Common Waxbill

• Ground insectivores: Eastern Meadowlark & Yellow throated longclaw

• Shoreline invertebrate feeders: Killdeer & Southern Lapwing

• Post-disturbance colonizers: species that specialize in newly disturbed habitats.

What is a niche, niche partitioning, and niche packing?

• Niche: the set of environmental conditions & ecological roles that allow a species to survive.

• Niche partitioning: species divide up resources to reduce competition (e.g., feeding at different heights).

• Niche packing: when all available niches are filled, leading to many species tightly coexisting (common in tropics).

What is ecological release?

Ecological release occurs when a species expands its niche because competitors are absent.

• Happens on islands or isolated habitats.

• Over evolutionary time, formerly specialist species may become generalists when competition disappears.

What is the army-ant following bird phenomenon?

Some tropical birds follow swarms of army ants.

• Ants flush insects into the open.

• Birds specialize in catching the fleeing prey.

• Classic example of a foraging guild and niche specialization.

How much individual variation is there within bird populations?

There is a lot of individual variation within bird populations. Individuals differ in:

• Morphology (size, plumage brightness, bill shape)

• Physiology (hormone levels, metabolism)

• Behavior (territoriality, migration timing, parental care)

• Life-history traits (fecundity, lifespan)
  This variation is essential for natural selection and adaptation

Why do scientists study individual variation in birds?

Studying individual variation helps researchers:

• Understand evolutionary processes (who survives and reproduces).

• Study behavioral ecology (why individuals make different decisions).

• Predict how populations respond to environmental change, climate shifts, and human impacts.

• Improve conservation strategies by identifying which traits affect survival.

How did humans drive megafaunal extinctions, and how did that affect birds?

As humans spread globally, megafauna (large mammals & birds) rapidly went extinct due to:

• Overhunting

• Habitat alteration

• Loss of keystone species

• Human-borne diseases
  This caused cascading effects on birds, including loss of scavengers, loss of habitats shaped by megafauna, and collapse of food webs.

What bird species lived in Pleistocene Florida before human contact, and what is “Pleistocene Florida”?

Pleistocene Florida = Florida during the Ice Age (~2.6 million–11,700 years ago), with cooler climate and different wildlife.
Birds present included:

• Two species of condors

• Teratorns

• Pygmy owls

• Black-billed magpie

• Hawk eagles

• Old World vultures

• Phorusrhacids (“terror birds”)
  These species later disappeared as climate warmed and humans arrived.

Give examples of birds that went extinct after European colonization and why.

• Carolina Parakeet — habitat loss, hunting, poultry disease

• Ivory-billed Woodpecker — logging, hunting

• Bachman’s Warbler — habitat loss

• Passenger Pigeon — mass hunting, habitat loss

• Dusky Seaside Sparrow — DDT, flooding of habitat

What are some major historical threats to birds, and how were they solved?

• Plume hunting (feathers for fashion) → stopped by Migratory Bird Treaty Act (1918).

• DDT poisoning → exposed by Rachel Carson’s Silent Spring → DDT restrictions and species recovery.
  These events helped launch modern bird conservation.

What laws protect bird species, and what do they do?

• Endangered Species Act (1973): identifies & protects threatened species; helped save the California Condor, Whooping Crane, Bald Eagle.

• Migratory Bird Treaty Act (1918): protects >800 species; bans killing, selling, or harming migratory birds; allows scientific & Indigenous-use permits.

Which is more harmful to birds: habitat loss or direct mortality?

Habitat loss is the #1 driver of modern bird declines and extinctions.

• Removes nesting sites and food resources

• Fragmentation increases predation

• Causes long-term population collapse
  Direct mortality (windows, cars, cats) kills millions/billions yearly, but habitat loss has more lasting population-level effects.

Give an example of a bird conservation project and how it helped a species.

Hawaiian Honeycreepers:

• Lost >50 species from habitat loss, mosquitoes, and avian malaria.

• Conservation includes:

  • Mosquito-control using Wolbachia bacteria (“birth control” for mosquitoes)

  • Captive breeding

  • Habitat restoration & fencing against mammals
    These efforts aim to stop malaria transmission and stabilize remaining species such as the ‘Akikiki and ‘Akiapōlā‘au.

How does the illegal wildlife trade affect bird populations?

• Thousands of parrots and songbirds are captured each year for the pet trade.

• Many die from stress, overcrowding, malnutrition, or suffocation during transport.

• Removes breeding adults → population crashes, especially for slow-reproducing species.

• Also spreads diseases between birds and across regions

What kind of position would you envision for yourself if you were to pursue a career in ornithology? (Here are some examples)

Possible careers include:

• Field biologist / wildlife biologist

• Conservation scientist

• Avian ecologist

• NGO conservation worker (Audubon, The Nature Conservancy, BirdLife)

• Museum ornithology research

• Banding technician / migration monitoring

• Environmental educator or outreach coordinator

• Wildlife rehab or rescue work

• Government biologist (USFWS, state agencies)