Bird Biology Quiz

Study Notes

Birds are archosaurs, a group of "ruling reptiles" that includes crocodiles and birds.
Birds are found in various habitats, including forests, deserts, and caves.

Birds likely evolved from small, carnivorous dinosaurs called theropods.
Archaeopteryx, from 147 million years ago, is the oldest known bird.
Shared features with theropods include a long bony tail, clawed fingers, and an S-shaped neck.
Birds have wings with feathers and a skull similar to modern birds.
Two main groups of birds:
- Paleognathae: flightless birds like ostriches and emus.
- Neognathae: flying birds with a keeled sternum and strong pectoral muscles.

Feathers:
- Unique to birds, homologous to reptile scales.
- Types of feathers:
  - Contour feathers: streamline the body, and include flight feathers.
  - Down feathers: provide insulation.
  - Filoplume feathers: hair-like, may have sensory roles.
  - Bristle feathers: found near eyes and mouths, likely sensory.
  - Semiplume feathers: fluffy, for insulation or courtship.
  - Powder-down feathers: aid waterproofing and parasite control.
Molting: replacing worn-out flight feathers, typically in pairs, to maintain balance.

Early birds were insectivores, but modern birds consume various diets (nectar, seeds, fish, small mammals).
Beaks are adapted for specialized feeding habits.
Digestive System:
- Crop: food storage.
- Stomach (two parts):
  - Proventriculus: secretes gastric juices.
  - Gizzard: grinds food with swallowed stones.
Birds have fast digestion to meet high demands.

Lay shelled amniotic eggs.
Mating Systems:
- Monogamy: one mate, often lifelong.
- Polygamy: multiple mates
  - Polygyny: one male, many females.
  - Polyandry: one female, many males.
Nests: built to protect eggs; often hidden.
Parental care: both parents often share, and some species have specialized care.

Flightlessness: evolved in some groups due to limited predation pressure.
- Penguins use wings for swimming.
Migration: stimulated by hormones due to day length.
- Navigation cues: visual landmarks, magnetic fields, celestial cues.
Senses: keen eyesight (hawks see from afar), good hearing, specialized vision for ultraviolet light in some species.

Birds are highly specialized for flight & survival in diverse environments; feathers, skeletal structure, respiratory, and reproductive strategies contribute to success.
Evolutionary lineage & behavioral adaptations highlight avian complexity.
Understanding birds illustrates broader evolutionary & ecological interactions.