OwlSheets
← Exit

Strutting Grouse and Chokecherry Pits

0 / 13

Strutting Grouse and Chokecherry Pits

Use refuge survey data to explain how behaviors and fruit structures help living things reproduce.

Dawn on the lek

Read the passage and Table 1. Then answer questions 1–4.

A Spring Survey at Antelope Draw

1Every spring, the crew at Antelope Draw National Wildlife Refuge surveys its greater sage-grouse, large birds that live on the sagebrush plains of the western United States. The refuge, the people and the numbers here are made up, but they are based on real wildlife studies. This year, sixth grader Kenji Abernathy joined refuge biologist Dr. Lucía Begay for the survey.

2Before sunrise on spring mornings, male sage-grouse gather on an open patch of ground called a lek. Each male fans his spiky tail feathers, puffs out his white chest and struts. As he struts, two bare yellow air sacs on his chest swell and then snap back, making popping sounds that carry across the plain. Females walk among the displaying males, watching and listening, and each female mates with just one or two of them. The males give no help with nests, eggs or chicks.

3From a parked truck, Kenji and Dr. Begay watched one lek for five mornings. They sorted the 24 males by where on the lek each one usually displayed, counted how often the males strutted and recorded every mating they saw.

4After mating, each female nests alone. She scrapes a shallow bowl in the ground under a sagebrush shrub and lays her eggs. While she sits on them, her mottled brown and gray feathers blend with the shadows, and she stays still even when a coyote walks nearby. Ravens often hunt for nests from the air. Later in the spring, the crew checked nests that it had found by following hens with radio collars.

5Chokecherry shrubs grow along the refuge's creek. In late summer, each small fruit turns from green to dark purple. While the fruit is green, the single seed inside is not yet ready to sprout. The seed has a hard, stony coat and is wrapped in sweet pulp. Birds such as robins swallow the ripe fruits whole. The pulp is digested, and the hard seed passes out in the bird's droppings, often far from the shrub where it grew.

6To learn more, volunteers set a trail camera on one chokecherry shrub whose branches held both green and dark fruits. They also planted seeds in the refuge nursery. All the seeds they planted came from ripe fruits of the same creek shrubs, except one group of seeds that they picked out of bird droppings under nearby fence posts.

Table 1. One Lek, Five Mornings
Where males displayedMalesStruts per 10 min (avg.)Matings seen
Center of lek31824
Middle ring8115
Outer edge1341
1.
Use Table 1.

What percent of all the matings seen went to the males at the center of the lek? %

2.
Use Table 1.

On average, how many matings did each male at the center of the lek have over the five mornings? matings per male

3.
Which conclusion does Table 1 best support?
Question 3 options
4.
Use paragraph 2. A male sage-grouse gives no care to eggs or chicks. Why can hours of strutting each spring still help him reproduce successfully?
Question 4 options

Hens and their nests

Use paragraph 4 and Table 2 to answer questions 5–8.

Table 2. Sage-Grouse Nests Checked This Spring
Shrub over the nestNestsEggs per nest (avg.)Nests that hatched
Tall, thick sagebrush20714
Short, sparse sagebrush1073
5.

What percent of the nests under tall, thick sagebrush hatched? %

6.
Which explanation of Table 2 fits paragraph 4 best?
Question 6 options
7.
The refuge wants more sage-grouse chicks to hatch next spring. Based on Table 2, which plan would most likely help the most?
Question 7 options
8.
Sort each sage-grouse trait or behavior from the passage by how it most likely helps reproduction.

Chokecherries along the creek

Use paragraphs 5 and 6 and Tables 3 and 4 to answer questions 9–13.

Table 3. Trail Camera on One Shrub, One Week in August
Fruit colorVisits taking a fruit
Dark purple (ripe)46
Green (not ripe)3
Table 4. Chokecherry Seeds Planted in the Nursery (50 in each group)
How seeds were plantedSprouted next spring
Inside the whole fruit6
Pulp removed by hand27
Picked out of bird droppings30
9.

The seeds picked out of bird droppings sprouted how many times as often as the seeds planted inside the whole fruit? times

10.
Which explanation fits all three rows of Table 4 best?
Question 10 options
11.
Use paragraph 5 and Table 3. How does a chokecherry fruit turning dark purple only once its seed is ready most likely help the shrub reproduce?
Question 11 options
12.
Match each structure or behavior from the refuge to the way it most likely helps reproduction.
13.
A visitor says, "Robins harm the chokecherry shrubs, because they eat the fruit that holds the shrub's seeds." Do you agree? Write a claim, give evidence from Table 3 and Table 4, and explain your reasoning about how the fruit's structures and the birds' behavior affect the shrub's reproduction.