Comparative Analysis of Nutritional Ecology

Differences in Species

Bearded vultures: Bones

Giraffes: Acacia tree leaves

Diet

Bearded vultures, as ossivores, have a specific diet: bones and sometimes the meat of carrion.
Giraffes, as herbivores, can only eat plants. In this case, acacia tree leaves, vines, and fruits.
Squirrels, as omnivores, have a more varied diet. They'll eat nuts, seeds, fruit, insects, and young birds.

Why are they so different?

Their diet depends on their digestive tracts and harvesting equipment.
Bearded vultures and giraffes eat what they are specialized to eat, while squirrels have more diversity.

Squirrels: Nuts, seeds, fungi, & insects

Digestive tract of a bird:

Most birds have a crop and gizzard, which aren't seen in mammals.

Digestive tract of a squirrel:

Their digestive tract is specialized to eat seeds or nuts, through the cecum.

Comparison of Digestive Tracts

Aves vs. Mammalia:

Birds, in the class Aves, have a different digestive tract compared to mammals.
Most mammals have compartmentalized stomachs or monogastric stomachs.
Bearded vultures have a two-part stomach, with a glandular stomach.

Ruminant vs. Nonruminant:

While giraffes and squirrels are both mammals, they differ in their digestive systems.

Giraffes are ruminants with a four-compartment stomach, specialized for the digestion of fibrous plant material and cellulose.
On the other hand, squirrels are nonruminants. Instead of a compartmentalized stomach, they are monogastric cecum fermenters.

Why are they so different?

Their diet and taxonomy explain this.
Bearded vultures are already different compared to giraffes and squirrels, since they belong to the class Aves instead of Mammalia.
Because bearded vultures eat bones, unlike most animals, they require adapted acidic stomachs.
Giraffes require a ruminant stomach because they eat only plants, while squirrels need a nonruminant stomach because they have a more diverse diet as omnivores.

Digestive tract of a giraffe:

Only ruminants have 4 compartments in their stomach.

Bearded vultures: Beak

Giraffes: Mouth & Lips

Harvesting Equipment

Bearded vultures use their beaks to carry and bring bones to eat or to their nest. Their beaks act as lips to tear at meat when they have the chance.
Squirrels' teeth continuously grow, allowing them to gnaw on dense food. The incisors are powerful enough to crack open seeds and tough shells.
Giraffes use their prehensile lips and tongue to grab at leaves. As ruminants, they regurgitate and rechew their food.

Why are each of them unique?

Each of these animals has different harvesting equipment specified for their diet.
As birds, bearded vultures have beaks, while giraffes and squirrels have teeth and lips.
However, giraffes and squirrels don't use their oral cavity the same way. Giraffes have prehensile lips and tongues that they use to grab leaves. Their permanent teeth grind on their food, while squirrels continuously grow teeth that wear down when gnawing on food.

Squirrels: Teeth

Similarities in Species

A giraffe browsing.

A bearded vulture soaring, on the look out for any carcasses.

Modes of Feeding

Bearded vultures and squirrels are similar in their modes of feeding; both are discontinuous feeders.
- They are both discontinuous feeders because they eat high-quality food infrequently.
Giraffes differ, as they are continuous eaters.
- They eat lower-quality foodstuffs and spend most of their time eating.
- Additionally, they are browsers because they mainly eat leaves.

What supports these classifications?

It makes sense that bearded vultures and squirrels are discontinuous feeders, since they eat foodstuffs that are not available at all times.
A bearded vulture has to scavenge for bones, and a squirrel has to forage for nuts.
Because leaves in trees are abundant, a giraffe would be a continuous feeder.

Social Behavior

Social Structure

Bearded vultures and squirrels are typically solitary creatures.
Conversely, giraffes live in herds, or "towers."

Dominance Hierarchy

All three animals have dominance hierarchies. They are determined by age and sex.
While male squirrels and giraffes are the most dominant in their hierarchies, bearded vultures differ.
Female bearded vultures are the most dominant in their hierarchies. They take the lead in nest building and can act more aggressively.

Mating System

Bearded vultures are generally monogamous and mate for life. The father and mother both care for their young!
However, giraffes and squirrels are polygynous and do not mate for life. In these two animals, the fathers do not help care for the young, and the mother bears the entire responsibility.

A herd of giraffes.

Competitive behavior: squirrels fighting over food.

A mating pair of bearded vultures.

How the IUCN classifies an animal's endangered status.

(Brown et al., 2014; The IUCN Red List of Threatened Species, 2016; The IUCN Red List of Threatened Species, 2021)

Endangered Status

Bearded vultures and giraffes are both declining populations
- Globally, Bearded vultures are listed as near threatened, and giraffes are listed as vulnerable.
Compared to squirrels, there are only a few subspecies of both the bearded vulture and giraffe. In contrast, there are 279 species of squirrel.
Several species of squirrel are listed as critically endangered to vulnerable.

Why are they threatened?

Though these animals are wildly different, they are affected by similar factors.
All three animals are negatively affected by habitat loss and fragmentation.
- With habitat loss, the giraffe and bearded vulture lose access to food, water, or nesting sites.
The bearded vulture and giraffe are both hunted, though the squirrel isn't.
Climate change additionally affects these animals, as it brings extreme weather.

Reference List

Brown, E., A. Peri, and N. Santarosa. 2014. “Sciuridae” (On-line), Animal Diversity Web. https://animaldiversity.org/accounts/Sciuridae/ (Accessed 02 December 2025.)
The IUCN Red List of Threatened Species. 2016. Giraffa camelopardalis. https://www.iucnredlist.org/species/9194/136266699 (Accessed 02 December 2025.)
The IUCN Red List of Threatened Species. 2021. Gypaetus barbatus. https://www.iucnredlist.org/species/22695174/154813652 (Accessed 02 December 2025.)

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