How many sounds does a brown thrasher make?

The brown thrasher is a species of bird that is known for making a wide variety of sounds. This medium-sized songbird inhabits shrublands and forests across much of the eastern and central United States. The brown thrasher is an omnivore that feeds on insects, spiders, seeds, berries, and small vertebrates. They are typically brown above with a white underpart with dark streaks. Their most recognizable feature is their long tail that they habitually cock up and down while foraging on the ground. The brown thrasher is the state bird of Georgia.

Range of Sounds

The brown thrasher is renowned for its elaborate and extensive vocalizations. They have an exceptionally large repertoire consisting of over 1,100 different song types. Their songs are composed of phrases that are repeated a couple of times before switching to a new phrase. Male brown thrashers learn new sounds throughout their life which allows them to regularly mix things up. The wide range of sounds they produce has earned them nicknames like “the forest mockingbird”.

Here are some of the key sounds that a brown thrasher makes:

• Long warbling songs
• Mimicking calls of other birds
• Harsh “chacks”
• Melodic whistles
• Musically complex trills and squawks
• Short pips and squeaks

The male is the primary singer and he sings from elevated perches high in trees. He uses his songs to declare his territory and attract potential mates. Females may also sing, but not nearly as often or as elaborately as the males. The male’s large repertoire enables him to sing for extended periods. In one study, a male brown thrasher was recorded singing over 3,000 phrases over the course of five hours.

Song Complexity

What makes the brown thrasher’s song so impressive is not just the immense variety, but also the complexity. Their songs contain notes delivered in rapid succession and spanning a wide frequency range. Here are some details on the complexity of their vocalizations:

• Songs range from 1 to 6 kHz in frequency
• Individual songs last from 3 to 15 seconds
• Songs can have upwards of 20 notes per second
• Phrases are repeated usually 2-4 times before switching
• Males combine 5-10 phrase types in a song bout

Researchers have analyzed brown thrasher vocalizations and confirmed their complexity ranks among the highest in the animal kingdom. The entropy, which measures randomness and thus complexity, of their songs is on par with hermit thrushes and mockingbirds. This all indicates the brown thrasher has vocal abilities comparable to the most skilled of songbirds.

Mimicry

Another signature feature of the brown thrasher’s vocal repertoire is their mimicking ability. They are able to accurately imitate sounds from over 70 different species of birds. Here are some of the birds they are known to copy:

• Northern cardinal
• Tufted titmouse
• Blue jay
• Chickadee
• Woodpecker
• Killdeer
• Eastern meadowlark
• Northern flicker

Brown thrashers incorporate mimicked songs from other birds seamlessly into their own vocalizations. Their ability to mimic combined with their innate vocal complexity allows them to have an exceptionally large song repertoire. However, while they may briefly mimic other species, the majority of their songs utilize their own distinct phrases.

Purpose of Sounds

The main reason male brown thrashers produce such long and complex songs is to attract mates. Females will evaluate the male based on his song and choose the most talented male singer. Males with larger repertoires demonstrate greater mental capacity and fitness since learning many song types takes skill. The male’s singing also serves to proclaim his territory. Birds with the most elaborate songs tend to get the best territories which offer valuable resources.

Here are some other common reasons brown thrashers vocalize:

• Communicating location – Contact calls notify other thrashers of an individual’s location
• Showing alarm – Harsh chacks identify threats or predators in the area
• Defending resources – Songs communicate territory ownership and willingness to fight
• Coordinating flock movement – Whistles and squeaks allow groups to stay together

The brown thrasher’s diverse vocalizations thus enable communication between individuals and support key behaviors related to mating and survival.

When Do They Sing?

Male brown thrashers will sing throughout much of the year, but their singing activity peaks during the spring breeding season. Here is an overview of when to expect increased vocalizations:

• Starting in late February, songs increase as males arrive at breeding sites
• Singing activity is highest in April and May during peak breeding
• After eggs hatch in May/June, singing decreases
• Another smaller peak occurs in late summer/early fall prior to migration
• Little singing happens in the winter when they live in flocks

Singing is largely under hormonal regulation and is triggered by longer days and increased testosterone in the spring. The males sing vigorously to establish their territory and attract a suitable female. Once the female begins incubating eggs, the male’s need to sing diminishes. The songs pick back up in late summer as the next breeding season approaches.

Individual Variation

While brown thrashers as a species have a huge repertoire of sounds, there is variation between individuals as well. Some key factors that influence an individual bird’s songs include:

• Age – Older males know more sounds and have better song development
• Exposure – Birds mimic sounds they hear locally while young
• Population – Regional dialect differences exist across populations
• Mutations – Rare random mutations can generate unique sounds

Studies that compared male brown thrashers across different sites found distinct phrases and mimicked species between populations. Within a population, males that lived in nearby territories had more song type sharing than distant birds. Young males also mostrar una mayor similitud en su repertorio con aves cercanas. Esto indica una combinación de factores regionales y de aprendizaje que generan variación entre individuos.

Daily Singing Duration

Brown thrashers are most vocal right after dawn and continuing through mid-morning. Singing activity typically begins around 30 minutes before sunrise and slowly tapers off by late morning. Here is an overview of their daily singing pattern:

• First songs 30 min before sunrise
• Peak singing at dawn and early morning
• Steadily declining songs late morning
• Very little midday singing
• Possible resurgence late afternoon
• Last songs around sunset

Males sing from high exposed perches facing towards the east as the sun comes up. This allows their songs to carry far and wide through the territory. The increased singing early in the day corresponds with when female activity also peaks as they forage. By midday it becomes too hot and singing drops off. Cooler temperatures in the late afternoon may bring another shorter round of songs.

During the peak of breeding season, total singing by an individual male may exceed 20,000 phrases per day. Across all seasons, the average duration of daily singing is around 4 hours but can reach as high as 5-6 hours per day during breeding season. This includes intermittent short breaks between active singing sessions early in the morning.

Singing Behavior

When singing, male brown thrashers exhibit characteristic behaviors to maximize sound transmission. Here are some details on how they sing:

• Perched on high exposed branches
• Head thrust upward during song delivery
• Tail held vertically upright and spread
• Wings slightly drooped
• Feathers sleeked
• Legs planted widely apart

They often make short flights from one singing post to another between song renditions. Males vigorously defend their singing posts against other males. Singing is used both to repel rival males and to attract prospective females that may be nearby.

Females give subtle cues that they are listening to the male sing via occasional wing fluttering or soft mewing sounds. If receptive, she may approach the male while he continues to sing from his elevated perch. Copulation typically occurs on the ground after the pair flies down from the trees.

Nestlings and Fledglings

While adult male brown thrashers are renowned for their songs, young birds also begin practicing vocalizations while still in the nest. Nestlings start making soft cheeping sounds a few days after hatching. These sounds are used to stimulate the parents to bring food.

The cheeping intensifies as the chicks get older and compete more aggressively for feedings. Just before fledging, nestlings expand their vocal repertoire to include more complex begging calls and imitation of adult songs.

Once on the ground, fledglings remain dependent on their parents for several weeks. During this time they continue honing their vocal skills by mimicking the mature songs of nearby adults. Juveniles begin wandering farther from their natal site after about a month. Dispersal peaks in the fall when the young thrashers leave to establish their own breeding territory.

Volume and Audibility

Brown thrasher songs are both loud and carry far through their habitat. Here are some details on the volume and transmission of their vocalizations:

• Song volume ranges from 80 to 100 dB measured at 5 feet
• Lower frequencies around 3 kHz travel farther before fading out
• Songs remain highly audible up to 300 feet away in ideal conditions
• Higher pitched sounds above 5 kHz attenuate more rapidly
• Males sing from high exposed perches to maximize range

The songs are loud enough to be easily heard by nearby birds over ambient noise. However, the higher pitched portions of their songs degrade over distance. Lower pitched components are better adapted for long-range propagation through the habitat. This allows males to effectively signal territorial ownership over a large area.

Visualizing the Data

To help summarize some of the key data points on brown thrasher vocalizations, here are some visual tables and charts:

Table 1. Examples of common brown thrasher song types

Chart 1. Seasonal variation in singing activity

These tables help summarize and compare different aspects of brown thrasher vocalizations to see patterns in song types, seasonal timing, and other data.

Conclusion

In summary, the brown thrasher has an exceptionally large and complex repertoire of songs and calls. A single male may know over 1,000 distinct song types made up of phrases repeated in combinations. Their mimicry ability allows them to imitate sounds from over 70 species of birds. Males sing to attract mates and defend territories, with peak singing occurring during the spring breeding season. Both regional dialect differences and individual variation exist across populations and birds. Understanding the wide range of sounds made by the brown thrasher provides insight into their advanced vocal abilities and communication strategies.