biology

Spix's red-handed howler

Spix's red-handed howler is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Spix's red-handed howler rather than just read about it. In short: Spix's red-handed howler (Alouatta discolor) is a species of Howler monkey native to the southeastern Amazon in Brazil. It is threatened by deforestation and hunting.

Key takeaways

Spix's red-handed howler belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Spix's red-handed howler to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Spix's red-handed howler from memory before moving on to harder problems.

Reference excerpt

Spix's red-handed howler (Alouatta discolor) is a species of Howler monkey native to the southeastern Amazon in Brazil. It is threatened by deforestation and hunting.

Taxonomy

The species was previously considered a subspecies of the red-handed howler, but it is now treated as a separate species.

Description Spix's red-handed howler has a similar appearance to the red-handed howler, but it has a yellowish-brown to reddish-brown back. Males weigh about 7.2 kg, females about 5.5 kg.

Distribution and habitat The species is endemic to central Brazil, specifically along the southeastern Amazon River in the State of Pará. It occurs mainly in the interfluvial land area between four rivers, Tapajós, Juruena, Xingú and Irirí. The westernmost limit of native habitat lies on the right bank of the Tapajós River and Juruena River and stretches east to the banks of the Xingú River and Irirí River. This strip of land extends northward to Forte Curupá (Gurupá), Brazil, which is the northernmost extent of the distribution of Spix's red-handed howler and also its type locality. Spix's red-handed howler mainly inhabits lowland forests separated by dry areas as well as forests affected by seasonal flooding.

Ecology The primary food source of this species is ripe and unripe fruit; it has the highest reliance on this food source of all species in this genus. A variety of species provide fruit year-round, but leaves supplement the sugars of the fruits with protein in their diets. When these food sources are limited, the howlers also supplement their diets with more mature leaves, flowers, woody plant matter, and sometimes fungi to possibly help digest the increased plant matter. Spix's red-handed howlers generally move in groups of 4-11 individuals, and have relatively small home ranges, 5-45 ha in size.

Conservation Spix's red-handed howler is currently listed as a Vulnerable species by the International Union for Conservation of Nature, based on a population decrease of over 30% over the past 3 generations, mainly due to habitat loss. The main threat to the species is habitat destruction by logging as well as land conversion for cattle ranching and soy plantations. Habitat fragmentation occurs through the presence of two major highways - the Cuiabá-Santarém highway runs through its range in a north-south direction and the Trans-amazonian Highway in an east-west direction. These roadways also pose the risk of fatality by vehicle collision. The habitat of the species is also heavily hunted (both commercially and for subsistence).

References

Further reading Fleagle, John G. (2013). Primate adaptation and evolution. Academic Press. Kinzey, W.G. (1997). "Alouatta". In Warren G. Kinzey (ed.). New World Primates: Ecology, Evolution, and Behavior. New York: de Gruyter. Milton, K. (1987). "Physiological Characteristics of the Genus Alouatta". International Journal of Primatology. 8: 428. doi:10.1007/BF02735769. S2CID 2689249.

Illustrations

Worked examples

Example 1 — a first encounter with Spix's red-handed howler

Start with the simplest possible case. Write down what Spix's red-handed howler claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Spix's red-handed howler before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Spix's red-handed howler ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Spix's red-handed howler

In research: Spix's red-handed howler appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Spix's red-handed howler in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Spix's red-handed howler is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arboreal mammals, Endemic mammals of Brazil, Fauna of the Amazon, so understanding it makes those chapters shorter.
In everyday life: Look for Spix's red-handed howler outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Spix's red-handed howler” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Spix's red-handed howler in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Spix's red-handed howler means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Spix's red-handed howler out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Spix's red-handed howler in simple terms?

Spix's red-handed howler (Alouatta discolor) is a species of Howler monkey native to the southeastern Amazon in Brazil. It is threatened by deforestation and hunting.

Why does Spix's red-handed howler matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Spix's red-handed howler?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Spix's red-handed howler.