4/14 real

nature journal week purpose

observe seasonal ecological changes and apply course concepts in the field

peak bird migration in Allegheny County

early May (1st–2nd week)

number of birds on peak migration nights

~50,000–60,000 birds per night

rose-breasted grosbeak

early migrating bird, visually distinctive

ruby-throated hummingbird migration

moves north in spring; arrival signals seasonal change

american woodcock

bird known for spiral “sky dance” mating display at dusk

hooded warbler

bright yellow bird with black hood; mid-late spring migrant

yellow-bellied sapsucker sign

straight horizontal rows of holes in trees

mesocarnivore breeding timing

breeding starts ~February; babies visible by spring

unihemispheric sleep

one brain hemisphere sleeps while the other stays awake

frigate bird sleep adaptation

sleeps while flying using unihemispheric sleep

stopover sites

locations where migrating birds rest and refuel

sleep debt in migration

birds accumulate sleep loss and recover at stopovers

breeding vs migration stress

breeding can be more sleep-depriving than migration

bird navigation cues

visual, celestial, olfactory, auditory, and magnetic

celestial navigation

using sun, stars, and constellations for orientation

magnetoreception

ability to sense Earth’s magnetic field for navigation

cryptochromes

eye proteins that may detect magnetic fields via quantum effects

magnetite hypothesis

iron particles in body potentially used for navigation

low-frequency sound navigation

some birds (e.g., pigeons) may use long-distance sound waves

evolution of beauty (The Evolution of Beauty)

aesthetic preferences can drive trait evolution via sexual selection

runaway sexual selection

trait and preference coevolve, exaggerating traits

non-adaptive traits

traits that persist without clear survival advantage (e.g., play, beauty)

human trophic position formula

TP = 1 + Σ(PDᵢ × Tₛᵢ)

average human trophic level

~2.4–2.5

humans compared to other animals

similar trophic level to pigs/anchovies

high trophic level diets

meat-heavy diets with larger environmental impact

global trophic trend

developing countries increasing trophic level over time

trophic level and GHG emissions

higher trophic diets → higher emissions

consumption efficiency

proportion of NPP consumed by herbivores

terrestrial consumption efficiency

~12%

aquatic consumption efficiency

~35%

why aquatic consumption is higher

phytoplankton are small and fully edible

why terrestrial consumption is lower

plants contain lignin and structural defenses

assimilation efficiency

proportion of consumed energy absorbed by organism

herbivore assimilation efficiency

~30%

carnivore assimilation efficiency

~80%

why carnivores are more efficient

animal tissue is chemically similar to consumer tissue

production efficiency

proportion of assimilated energy turned into biomass

ectotherm production efficiency

~35%

endotherm production efficiency

~2%

why endotherms are inefficient

high energy cost of maintaining body temperature

trophic transfer efficiency

~10% of energy passed to next trophic level

trophic pyramid implication

higher levels require exponentially more biomass below

landscape ecology

study of spatial patterns and their effects on ecological processes

composition (landscape ecology)

types of habitats present

configuration (landscape ecology)

spatial arrangement of habitats

grain (scale)

size of smallest unit of observation

extent (scale)

total area or duration studied

fine grain vs coarse grain

fine = detailed resolution; coarse = broader units

importance of scale

ecological patterns depend on grain and extent

GIS (geographic information systems)

tools for analyzing spatial ecological data

GIS applications

mapping species distributions, habitat types, and conservation areas

habitat heterogeneity

variation in habitat types across a landscape

importance of heterogeneity

increases biodiversity and ecological complexity

legacy effects

past events influencing present ecosystems

esker

ridge formed by sediment from subglacial rivers

biotic legacy example

tree structure revealing past open-field conditions

anthropogenic legacy example

Roman settlements altering soil nutrients and biodiversity

Chernobyl disaster ecological impact

wildlife rebounded despite radiation; human absence increased biodiversity

chernobyl frog adaptation

darker pigmentation linked to radiation resistance

disturbance (ecology)

events that alter ecosystem structure

small frequent disturbance

increases heterogeneity

large severe disturbance

creates uniform landscapes

fire suppression legacy

reduced small fires → fuel buildup → larger modern fires

climate change and fire

increases fire season length and severity

ecosystem engineer

organism that modifies habitat structure

beaver example

creates wetlands by building dams

coral example

builds reefs supporting high biodiversity

woodpecker/sapsucker role

create cavities used by other species

humans as ecosystem engineers

most impactful modifiers of ecosystems

species-area relationship (SAR)

species richness increases with area

SAR equation

S = cA^z

log-transformed SAR

log S = log c + z log A

typical z value

~0.2–0.35

interpretation of SAR

larger areas support more species but with diminishing returns

Island Biogeography Theory

species richness determined by colonization and extinction balance

colonization rate

decreases as species richness increases

extinction rate

increases as species richness increases

equilibrium species richness

point where colonization = extinction

effect of distance on islands

farther islands have lower colonization rates

effect of island size

smaller islands have higher extinction rates

highest biodiversity islands

large and near mainland

lowest biodiversity islands

small and far from mainland

habitat islands

isolated habitat patches functioning like islands

example of habitat island

urban parks surrounded by development

conservation application of island biogeography

informs reserve size, spacing, and connectivity

SLOSS debate

one large vs several small reserves

importance of connectivity

corridors reduce extinction risk and increase colonization

global trade effect on biodiversity

increases colonization (including invasives)

land development effect on biodiversity

increases extinction rates

modern island biogeography update

includes human impacts like trade and development