The Mariposa Grove 

of Giant Sequoias 

In 1864, for the first time 

in history, the United States 

Congress passed an act 

protecting two pieces of land 

for preservation and public 

use, forever. This act laid the 

foundation for the national 

parks and protected areas in

our country today. Those two

pieces of land were Yosemite 

Valley and the Mariposa 

Grove of Giant Sequoias.

The ecology of giant sequoia 

groves is complex and 

remarkable. We often think of 

fire as a bad thing, but 

sequoia ecosystems depend 

on it. Frequent fires clear the 

immense amount of branches, 

needles, and cones on the 

forest floor, enriching the soil 

so sequoia seedlings can 

thrive. When there is no fire, 

there is not enough open 

space or nutrients for new 

sequoias to grow. 

The cones of the giant sequoia 

are small and secure; tightly 

retaining over 200 seeds 

inside. Another reason 

sequoias need fire is to open 

up those tightly sealed 

cones and release the tiny 

seeds inside to float down to 

the forest floor, where they 

can germinate and grow. 

Perhaps the most famous tree 

in the grove, the Grizzly 

Giant, is about 1,800 years 

old. Can you imagine the 

millions of people and animals 

who have come and gone and 

been thankful for 

that one tree? 
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Raccoons 

in Yosemite 

Raccoons are adaptable 

and intelligent animals, 

and use their dexterous and 

sensitive front paws to forage 

for food such as insects, 

frogs, crayfish, and plant 

matter. Like bears, they can 

easily learn to use human 

development as a food 

source. This causes many 

problems for raccoons and 

people alike. Raccoons in 

Yosemite have been known 

to go as far as to unzip tents 

or run off with backpacks to 

eat any food forgotten 

nside- another reason to 

store your food in a bearresistant food locker when 

camping! 

Food left out around human 

development can cause 

unusually high populations of 

raccoons to collect where 

people spend time. This is 

problematic because of the 

changes it causes to 

raccoons, but also for human 

safety. Not only do 

Yosemite's raccoons can 

carry diseases dangerous 

to people, but the presence 

of raccoons (and other 

smaller mammals, including 

squirrels) in turn attracts 

arger predators like 

mountain lions and coyotes. 

Store your food properly, 

never feed or approach 

any wildlife, and avoid 

leaving 

"microtrash" (scraps from 

cooking, etc.) behind! 

These steps can help to keep 

raccoons safe and you 

healthy. 
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Speeding 

Kills Bears 

(And Other Wildlife!) 

Black bears are one of the 

most iconic and beloved 

animals in Yosemite. 

Unfortunately, for bears, 

living here comes with 

some serious drawbacks. 

One of those is that four 

million visitors each year 

means millions of cars on 

Yosemite's roads; many 

with distracted drivers, 

folks who are not familiar 

with the area, or folks who 

are excited to get where 

they are going. More than 

400 bears have been hit 

by cars in Yosemite since 

1995-and often, 

collisions with vehicles are 

fata I to bears. 

It is not just bears who face 

danger on Yosemite's 

roads: owls, Pacific 

fishers, butterflies, rare 

amphibians like frogs 

and salamanders; and 

mammals like deer, foxes, 

and mountain lions are 

also often hit and killed on 

Yosemite's roads. 

If you want to help save 

wildlife, stay alert! Scan the 

sides of the road in front of 

your car and obey posted 

speed limits. Talk to your 

friends about why it is 

important to drive slowly 

and pay attention while 

driving on the roads in 

Yosemite! 
 

Wildlife Science 

in Yosemite: 

Wildlife Tracking 

There are many ways that 

wildlife biologists find out 

new information about the 

animals they study. One of 

them is by tracking wild 

animals. 

Biologists use tracking devices 

in the form of collars, tags, or 

tiny antennas to track wild 

animals. This gives biologists 

the ability to find out more 

information about where 

animals are moving, how 

large of an area they use, and 

what kind of habitat they use. 

Some tracking devices send 

GPS points directly to 

biologists, and tell them 

where tagged animals are 

moving every hour. Other 

devices store data and 

biologists have to retrieve the 

data later. Still other trackers 

don't collect GPS data, but 

instead, help biologists locate 

animals by putting out a radio 

signal (telemetry). This signal 

can be picked up using a radio 

receiver and an antenna, like 

in the picture here! 

Biologists make sure that 

tracking devices weigh less 

than 3% of an animal's body 

weight, and that they are 

made of smooth, safe 

materials, so that they do not 

harm wildlife. The 

information biologists collect 

by tracking wildlife helps 

better understand and 

protect many species within 

the park!