Download Sonoran Desert Phenology Calendar

Sonoran Desert
Phenology Calendar
Photo credits: Steve Amesbury.
Phenology: an introduction
What is phenology?
Phenology is the study of the timing of cyclic or seasonal plant and animal life
cycle events that are influenced by environmental conditions, including
variations in weather and climate. Derived from the Greek words phaino,
which means “to appear”, and logos, which means “to study”, the observation
of phenological events (termed “phenophases”) in nature has been going on
for millennia: the earliest humans observed and planned their lives around
plants' growing seasons and the presence of animals for hunting. Written
records of plant and animal phenology are available from hundreds of years
back, including cherry blossom timing in Japan and grape harvesting in
Europe.
Why is phenology important?
Phenology is nature’s “biological clock”, an integrated measurement of the
interactions between the atmosphere and the Earth. Phenology is valuable in
many ways:
· Phenology relates to human issues like agricultural production, health (e.g.,
allergies, timing of vector-borne diseases) and recreation and tourism
· Phenological patterns relate to environmental change due to altered climate
and ecosystems; thus phenology can be utilized in natural resource
conservation and management
· Phenology can be assessed and monitored at different scales that relate to
individual plants or animals, populations, communities and/or ecosystems,
offering a potent look into those systems’ health and functioning
What causes phenology?
The three key environmental drivers of phenology are
photoperiod (length of daylight hours), temperature, and the
availability of moisture. The combination and interaction of
these three drivers impose complex and varying controls on
phenology events in different parts of the globe.
· Photoperiod provides plant and animal species with a
consistent annual climatic signal. Photoperiod can trigger
the growth and death of leaves and animals’ biological
clocks, e.g., reproduction, migration, and molting of feathers
or fur.
· Temperature can regulate growth and development
patterns of plant and animal species. Many plants require a
chilling period for their seeds to grow; other plants and
animals go dormant in either very hot or very cold
seasons. In temperate areas plant phenology is often
driven by the combination of photoperiod and temperature.
· Moisture availability (e.g., rain or snow) is important for
plant and animal species because it affects the ability and
rate of cell division, for example in leaves and in eggs of
amphibians. Water limitation is especially important in the
deserts of the world, and the combination of precipitation
and photoperiod affects phenology in the tropical areas of
the world.
Measurement of phenology
Every living thing experiences and responds to the changing of seasons. Thus, we can observe phenology in individual plants or
animals, populations of the same or different species, and entire communities, as each member responds to changes in light, moisture,
temperature, and even the phenophases of other organisms. Observation of phenological events includes noting, for example, when
individual flowers appear on a rose bush, when different rose bushes flower, when bees begin to show up to pollinate the roses, and what
other plants the bees also pollinate at that time. Tools for observing phenology include the human eye of course, as well as cameras,
satellites, and tools to measure the amount of pollen in the air or bacteria in the soil. Phenology can be measured across minutes, hours,
days, and months, and changes in the timing of phenological events can be measured across seasons or among years to millennia.
Photo credits: National Park Service.
Phenology: examples
Plant Phenology
The most readily visible example of phenology is in the leafing, flowering, and fruiting of
plants. The phenology of trees can be especially interesting to study because specific
individuals can often be monitored for long periods of time. This helps to reduce the
effects of individual variation in the timing of phenological events, making trees
potentially a more sensitive tool for identifying changes in phenological timing caused by
global climate change.
Trees show a variety of phenophases in the development of leaves, flowers, fruits,
and seeds. Each of these features functions in different ways in the lives of trees -leaves are needed for photosynthesis and growth, flowers are the organs of
reproduction, and fruits and seeds are involved in plant dispersal – and each responds
to different environmental factors. The cycle of leaf development from bud to deciduous
leaf fall is related to rainfall, day length, and temperature. Flower development is often
timed to correspond with the availability of pollinators. Fruit and seed production may
be influenced by the presence of seed dispersal agents like wind and fruit-eating
animals. Thus it is possible that the seasonal patterns of each of these phenophases is
linked to different environmental cues and may be affected in different ways by
environmental change.
Animal Phenology
Birds, fish, and mammals such as deer and bobcat are all attuned to the seasons of the
Earth. Some of the most studied phenological events are the mass migrations of
animals between regions, continents and even globally (e.g., whale and sea bird
migrations across entire oceans). Animals such as snowshoe hares, elk and deer
change the way they look, becoming a different color or growing antlers based on
seasonal changes, and bears and amphibians will hibernate during inhospitable
seasons.
Insect populations are also attuned to the rhythms of climate. Population dynamics
are often controlled by climate variables like temperature, which restricts survival and
precipitation, which restricts reproduction for species whose young rely on standing
water. Insects are also important members of a complex ecology where species
interact on multiple levels. Plants often provide food and, in return, many insects help
plants pollinate. Disruption of the cycle of one species might therefore have significant
consequences on another species. Insects also act as pests by destroying crops or
seriously damaging other vegetation. They can also act as disease vectors for
pathogens such as West Nile Virus and Dengue Fever. Thus the phenology of insects is
highly tied to the phenologies of other animals, plants, and human systems.
Photo credits: Amanda Barnard, National Park Service.
Phenology and humans
Economics. Human activities are in large part affected by the
environmental context within which particular communities live,
and economic activities are not an exception. Phenological
events (especially those driven by temperature and
precipitation) are routinely taken into account when engaging in
agriculture, cattle ranching, wildlife management, tourism,
regional fruit harvesting, and every other activity that involves a
live component and therefore life cycles. Examples wherein
phenology constitutes an important tool for economic activities
include controlling crop plague, determining suitable crops for a
specific season, determining the best time for the harvesting of
game species or regional fruits, etc.
Disease. For thousands of years it has been observed that
many human diseases are more likely to occur during specific
times of the year, such as influenza and the common cold.
Unlike most phenological phenomena, human diseases with a
phenological signature are typically most active in the winter. In
addition to the common phenological diseases that are
experienced across the globe, inhabitants of the Sonoran
Desert are vulnerable to unique diseases that are only
experienced by a few regions in the world, such as
coccidioidomycosis or "valley fever".
Invasive species. Exotic invasive plants often experience
different phenological responses than native plants to annual
and seasonal changes in temperature and precipitation,
differentiating them functionally from natives. Frequently
invasive species are found to respond to precipitation faster
than natives and set flower sooner, drawing soil moisture down
and extracting nutrients otherwise available to natives.
Understanding the phenology of invasive species is critical to
management and control efforts; chemical and manual
treatments depend on the status of the soil and the phenology
of the plant.
Phenology in the Sonoran Desert
Unique climate, unique phenology
The Sonoran Desert, spanning parts of southwestern USA and northwestern Mexico (shown in the bottom right, as defined
by the World Wildlife Fund), has two rainy seasons but is overall hot and dry. These climatic features result in unique
phenological traits of the species living in this biome. Light is rarely limiting and temperatures rarely stay below freezing;
overall there is high sensitivity of both plants and animals to the availability of water and the avoidance of extreme
heat. Many plants can respond to specific rainfall events, flowering numerous times in one growing season; both plants and
animals can become dormant in times of drought. These characteristics provide unique opportunities and challenges in
observing and measuring phenology in the Sonoran Desert.
The above graph summarizes the climate of the Sonoran Desert using
temperature and precipitation data from the Arizona Meteorological
Network (http://ag.arizona.edu/AZMET/). Three points in the Sonoran
Desert of Arizona (Tucson, Yuma and Paloma) for the period 1992-2007
were used to generate daily averages for high (red line) and low (blue line)
temperatures, and the probability of precipitation (green line). In addition,
the daily high (red dot) and low (blue dot) temperatures experienced over
the entire period are plotted to give readers the sense of the range of
temperatures that may be experienced during specific times of the year.
Similar climate figures were made for each month.
Photo credits: Andy Fisher, National Park Service.
Related links:
There are countless sources of information about
phenology on the internet. Below are a few links that
provide overviews of phenology and its use in monitoring
the state of the planet; each contains many more links of
interest.
- Project Budburst
http://www.windows.ucar.edu/citizen_science/budburst/
- Monarch Watch
http://monarchwatch.org
- USA National Phenology Network: http://www.usanpn.org
- University of California Santa Barbara Phenology
Stewardship Program:
http://www.ucsbphenology.christophercosner.com
- Arizona-Sonora Desert Museum Migratory Pollinators
Program: http://www.desertmuseum.org/pollination
- Intergovernmental Panel on Climate Change:
http://www.ipcc.ch
About this Calendar:
This calendar was produced as a final project for the class “The Geography
of Phenology” (GEOG696C) in the Department of Geography and Regional
Development at the University of Arizona. Contributors to the development
of the calendar include Dr. Willem J.D. van Leeuwen (instructor), Steven
Stewart Amesbury, Armando Barreto Muñoz, Jennifer Davison, Jahan
Kariyeva, Cory W. Morin, Aaryn Dyami Olsson, Jose Raul Romo Leon and
James Derek Tamerius.
Sources:
-http://www.saguaro-juniper.com/i_and_i/cacti/saguaros/harvest/saguaro_fruit.html
-http://edc.usgs.gov/guides/avhrr.html
-http://en.wikipedia.org/wiki/SPOT
-http://geo.arc.nasa.gov/sge/landsat/lpchron.html
-http://www.itc.nl/research/products/sensordb/Launch_Schedule.aspx
-http://www.sonoraturismo.gob.mx/caceria-en-sonora.htm
-http://www.whatbird.com/
Special Thanks:
-http://www.wrcc.dri.edu/
We would like to acknowledge the following
parties for the information and pictures that
made this project possible:
- Epple, Anne Orth. 1995. A field guide to the plants of Arizona. Falcon,
Guilford, CN.
T. Beth Kinsey and The Firefly Forest
http://fireflyforest.net/firefly/
- Veronica Cornonado Peraza
- The Arizona-Sonora Desert Museum
http://www.desertmuseum.org/
- The National Parks Service
http://www.nps.gov/
- USGS Arizona Water Science Center
http://az.water.usgs.gov/
- Rogelio Lizarraga
www.bamury.com
- Don Knight, Stephen Minter, and Mark
Dimmitt, ASDM Sonoran Desert Digital Library.
- Kearney, Thomas H., and Robert H. Peebles. 1951. Arizona flora.
University of California Press, Berkeley.
- McGinnies, William G. n.d. Flowering period for common desert plants,
southwest Arizona. Office of Arid Lands Studies, College of Agriculture,
University of Arizona.
- Phillips, Steven J., and Patricia Wentworth Comus, eds. 2000. A natural
history of the Sonoran Desert. Arizona-Sonora Desert Museum Press,
Tucson.
- Turner, Raymond M., Janice E. Bowers, and Tony L. Burgess. 1995.
Sonoran Desert plants, an ecological atlas. University of Arizona Press,
Tucson.
- USDA. 2008. Plants database. Natural Resources Conservation Service.
U.S. Department of Agriculture. http://plants.usda.gov/index.html
January
The coolest period of the year typically begins in
the last week of December and continues through
the first week of January. Temperatures typically
are near 20˚C during the day and often
reach freezing temperatures at night. Winter
storms bring precipitation in the form of rain for
most of the low elevations and snow at higher
elevations. Most vegetation is dormant during this
month, but some desert fruits ripen and trees
begin to sprout new leaves.
Although unusual, occasionally the desert
valleys receive a dusting of snow.
Species such as Freemont cottonwood (Populus
fremontii) may begin to blossom and the fruit of
Christmas cactus (Schlumbergera bridgesii) will
ripen.
Photo credits: (Top right, bottom right, and background) T. Beth Kinsey, the Firefly Forest; (Bottom left) T.R. Van Devender.
Desert mistletoe
(Phoradendron californicum)
cover many trees during this
period. They are a great food
source for birds that are active
such as the curve-billed
thrasher (Toxostoma
curvirostre, right) and the
cactus wren (Campylorhynchus
brunneicapillus, below).
January
Sun
January is breeding season for the mule
deer (Odocoileus hemionus) . Males put
much of their energy into competing for
mates, often making them more
susceptible to attack by cougars (Puma
concolor), who are also very active
during this month.
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Record Low
(1913): 6F
Max Monthly Precipitation (1993): 5.58 inches
Record High
(1971): 90F
Photo credits: (Top right) Rhonda Spencer, Arizona-Sonora Desert Museum; (Top middle) Warren Lynn, Arizona-Sonora
Desert Museum; (Top left) Jeanne Broom, Arizona-Sonora Desert Museum; (Bottom left) Paul Berquist, Arizona-Sonora
Desert Museum; (Background) T. Beth Kinsey, the Firefly Forest.
February
On the cusp of springtime in Arizona, February can
provide balmy days and snowy storms with seemingly
equal probability. Shifts in bird phenology increase in
the Sonoran Desert in February. Cinnamon teal (Anas
cyanoptera), Western grebes (Aechmophorus
occidentalis) and other early north-bound migrants
begin to arrive. Wintering ducks show brighter
plumage, preparing for breeding season. Wintering
raptors such as ferruginous hawks (Buteo regalis) and
red-tailed hawks (Buteo jamaicensis, right) remain
abundant.
Photo credits: (Top right, bottom left) Beth Kinsey, the Firefly Forest; (Background) Jennifer Davison.
February
Sun
Nesting is underway for Costa’s hummingbirds
(Calypte costae, male shown above) in
February. Some individuals are year-round
residents, while others migrate to the Sonoran
Desert in late winter or early spring, continuing
on to the highlands of Arizona and California
when temperatures get too hot. With nesting
sites in desert scrub (right), chaparral and
tropical deciduous forest, Costa's
hummingbirds rely not only on the flowers
becoming abundant at this time of year but the
insects that frequent those flowers.
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
* 1986,
SPOT-1
Record Low
(1899): 17F
Max Monthly Precipitation (1905): 4.15 inches
Record High
(1957): 93F
Photo credits: (Left) T. Beth Kinsey, the Firefly Forest; (Right)
(Right) Willem J. D. van Leeuwen;
Leeuwen; (Background) Jennifer Davison.
* Satellite launch dates.
March
A great diversity of plant and animal species live in
streamside riparian habitats in the Sonoran Desert. Two
tree species dominate these habitats, the Freemont
cottonwood (Populus fremontii; above left) and the
Goodding willow (Salix gooddingii; above right). Flowering
in both these species generally begins in early spring.
Photo credits: Steve Amesbury.
Spring wildflowers begin to bloom in February
and peak in March following wet winters in the
Sonoran Desert. The Mexican gold poppy
(Escholtzia mexicana, right) may bloom in such
profusion that entire hillsides turn orange for
several weeks. Many shrubs and trees flower
at this time, too, including the invader, salt
cedar (Tamarix ramossissima, below). Saltcedar grows in rpiarian areas, where it
competes with native riparin trees. Although it
is not native to this region, some native
species of birds have adopted it for nesting.
March
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
27
28
Vernal
Equinox
22
23
24
29
30
31
Record Low
(1897): 22F
25
26
Max Monthly Precipitation (1905): 3.88 inches
Photo credits: (Bottom left and background) Steve Amesbury; (Top right) Beth Kinsey, the Firefly Forest
Record High
(1988): 98F
April
The trees of the Sonoran Desert flower later than the
wildflowers, including the blue palo verde (Parkinsonia florida;
below left) and the foothills palo verde (P. microphylla; below
right). Both bloom during April, but the flowers of the blue
palo verde appear one to two weeks before those of the
foothills palo verde. The staggered blooming times help to
prevent hybridization between the two species, both of which
are pollinated by native bees and the introduced honeybee.
Other trees that flower at this time include the honey
mesquite (Prosopis glandulosa). The mesquite’s leguminous
pods will be an important food source for much of the desert’s
fauna in the coming months. Meanwhile, most desert cacti
are putting on flower buds and may be already blooming. The
prickly pear (Opuntia spp.) (center) provides pollen for bees
and migrating birds.
Photo credits: (bottom left and right) Steve Amesbury; (bottom center) Aaryn Olsson.
The orchid-like flowers of the desert willow (Chilopsis linearis; right)
are a beautiful pink or purple color. They first begin to appear in April
and last until August. Desert willows are most often found in arroyos
or near streams. During the autumn and winter, they lose their
leaves.
The velvet mesquite (Prosopis velutina) is the common
species of mesquite in the Sonoran Desert. It
generally begins to bloom in April. The flowers are
small and form an elongated cluster called a catkin.
Groves of mesquite, known as bosques (below), often
line arroyos.
April
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Record Low
(1901): 28F
Max Monthly Precipitation (1905): 3.53 inches
Record High
(1965): 104F
Photo credits: (Top right, bottom left, and background) Steve Amesbury; (Top middle, Top left) Mark Dimmitt, ArizonaSonora Desert Museum
May
Saguaros bloom in April and May, providing a
valuable nectar source for the endangered Lesser
Long-nosed bat (Leptonycteris curasoae). This bat
undertakes long migratory flights, relying on the
nectar from columnar cacti such as the saguaro and
organ pipe cactus (Stenecereus thurberi). Their
dependence on nectar necessitates a tight coupling
of their migration with the timing of flowering of the
saguaro and other cacti. Therefore, the paths these
bats take are often called “nectar corridors.”
The white-winged dove (Zenadia asiatica) is another
migrant that utilizes the saguaro.
Photo credits: (Top left) Merlin D. Tuttle, Bat Conservation International; (Background).
May
Sun
Ironwoods (Olneya tesota) break buds in
late April and early May, flowering for 1018 days before shedding their flowers,
leaving a pink blanket on the desert floor.
Flower production is variable, with large
production occurring every 2-5 years.
Insect pollinators, including many species
of bees, visit the ironwood flowers, whose
flowers persist beyond the flowering
phase of palo verdes (Cercidium spp.).
The anatomy of the pea-shaped flower
(upper right) requires the pollinator to bury
itself between the petals, ensuring it picks
up and deposits pollen during its visit.
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Record Low
(1899): 32F
Max Monthly Precipitation (1931): 1.34 inches
Photo credits: (Top left and background) Mark Dimmit, ArizonaArizona-Sonora Desert Museum.
Museum.
Record High
(1910): 111F
June
One of the main economic activities in the Sonoran
Desert region is cattle ranching, these activities are
strongly related to phenological responses from
the desert to climatic pulses. Rain will affect the
timing and quantity of plant production, directly
impacting cattle ranching.
Other important activities are tourism and hunting.
Hunting is regulated by specific cyclic events
intrinsic to all species such as mating or birth of
wildlife. Tourism is conducted at different times of
the year in the presence of events such
as flowering, fruit harvesting and wildlife spotting.
Photo credits: (Top right) Jacinto Mayboca Esparza ; (Bottom left) Jose Raul Romo Leon; (Background) Don Knight.
Some of the traditional activities
related to harvest the native flora
happen during June:
The traditional saguaro
(Carnegiea gigantea) fruit harvest
of the Tohono O’odham (Desert
People) Nation takes place
primarily during this month.
June
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Summer
Solstice
21
22
23
28
29
30
Record Low
(1908): 43F
Photo credits: T. Beth Kinsey , the Firefly Forest.
24
25
Max Monthly Precipitation (1938): 2.07 inches
26
27
Record High
(1960): 115F
July
Prior to 2008 the Arizona Monsoon was
defined as beginning after the third
consecutive day of dew points above 55oF.
On average this concurred around July 7
with the monsoon continuing for the next two
months. Starting in 2008 the National
Weather Service has defined the Arizona
monsoon as beginning on June 15 and
ending on September 30
Photo credits: USGS, Arizona Water Science Center.
Average high temperature: 105
Average low temperature: 80
Warmest ever: 121
Coldest ever: 61
Average precipitation: .8
Vegetation
greenness is
measured here
by the MODIS
sensor, on the
TERRA satellite.
Satellites are
routinely used to
measure
landscape-scale
phenology.
With the arrive of the monsoon the Sonoran
desert landscape changes dramatically from
arid and dry scenery to a green humid-warm
and vivid ecosystem.
From a phenological point of view, many
processes occur during this month in an
accelerated way, influenced by the excessive
sun hours (photoperiod), precipitation, and
higher temperatures. The result is an increase
in vegetation greenness, meaning more food
for animals and humans.
July
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
30
31
* 1972,
Landsat 1
26
Drought Levels Based on
Monthly Streamflow discharge,
July 2008
Record Low
(1911): 49F
Photo credits: USGS, Arizona Water Science Center.
27
28
29
Max Monthly Precipitation (1984): 7.56 inches
Record High
(1995): 115F
* Satellite launch dates.
August
August is the peak of the monsoon season and
month with the greatest rainfall (~3 in) in the
Sonoran Desert, which only averages 3-15 inches
of rain per year. Monsoon is defined as a seasonal
change in the wind direction with strong and brief
thunderstorms that bring heavy rain. The summer
monsoon in the Sonoran Desert brings moisture
from the Gulfs of Mexico and California. The winter
and summer rain seasons and mild winters of the
Sonoran Desert enable its unique biodiversity.
Populat household plants such as Caesalpinia
(bottom left) and Tecoma stans bloom throughout
the monsoon season.
Photo credits: (Top) T. Beth Kinsey, the Firefly Forest; (Bottom) Willem J. D. van Leeuwen; (Background) Jahan Kariyeva.
Sonoran desert toads (Bufo alvarius) emerge following the
rains to feed and breed in large temporary rain pools. During
the rest of the year this species hibernates underground.
Sonoran desert toads occur in a number of habitats ranging
from creosote bush desert scrub and grasslands to oak-pine
woodlands and tropical deciduous forests. These toads
consume a large variety of insects throughout their lives.
August
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
August is the month of the distinctive
buzzing sound in the melodies of the
Sonoran Desert. These signature sounds
are the mating tunes of the male cicada.
Sonoran Desert or Apache cicadas
(Diceroprocta apache) are the only
insects known to be able to cool
themselves by sweating during summer
heat. Adult cicadas feed on the watery
liquids inside trees and
nymphs feed from tree
roots underground
during their few years
of development.
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Record Low
(1917): 55F
Max Monthly Precipitation (1935): 5.61 inches
Photo credits: (Top and bottom) T. Beth Kinsey, the Firefly Forest; (Background) Jahan Kariyeva.
Record High
(1944): 112F
September
September is a transition
month climatologically and
biologically. The monsoon
rains recede rapidly and
drier conditions increase.
Temperatures are still hot
but may cool towards the
end of the month as
summer ends and fall
begins.
Plants and flowers like the turpentine bush
(Ericameria laricifolia) are still blooming from the
monsoon rains. The prickly pear's fruit (Opuntia
spp.) become fully ripe and ready to eat.
September is the breeding season for big horn
sheep (Ovis canadensis).
Photo credits: (Top and Background) T. Beth Kinsey, the Firefly Forest; (Bottom Left) Paul Berquist, Tucson Sonora Desert
Museum.
September is a time of insect
activity due to standing water
from the monsoon rains. The
risk of West Nile Virus
transmission from mosquitoes
is high. Brilliant butterflies like
the gray hairstreak (Strymon
melinus) will decorate and
pollinate the landscape.
September is the peak time of bird
migration. A variety of birds can be seen
passing through or settling in for the
winter. Rufous hummingbirds
(Selasphorus rufus) arrive for the winter
while Western Kingbirds (Tyrannus
verticalis) gather to migrate south.
September
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
29
30
Autumnal
Equinox
27
Record Low
(1965): 42F
28
Max Monthly Precipitation (1996): 4.41 inches
Record High
(1950): 112F
Photo credits: (Top left) Stephen Minter, Tucson Sonora Desert Museum; (Top right) T. Beth Kinsey, the Firefly Forest; (Bottom
left) Paul and Joyce Berquist, Tucson Sonora Desert Museum; (Background) T. Beth Kinsey, the Firefly Forest.
October
October brings a noticeable change in temperatures and
precipitation, as the days shorten and the monsoon season
officially ends. Precipitation decreases markedly and
temperatures begin to vary more between day and night, both
climatic shifts providing signals to plants and animals to begin
their next phenophase. Many plants start to turn color in
October, due to an interruption in chlorophyll production and
subsequent increase in the reds and yellows reflected by other
chemicals, e.g., anthocyanins. A leafless coralbean (Erythrina
flabelliformis) at right and a summer annual (below) show that
autumn colors can be quite dramatic in the Sonoran Desert.
Photo credits: (Bottom) T. Beth Kinsey, the Firefly Forest; (Top) Willem J. D. van Leeuwen; (Background) Jahan Kariyeva.
As the autumn progresses resident birds briefly sing again,
and migrating birds make a south-bound pass through the
Sonoran Desert. Wintering hawks and hummingbirds arrive,
and summering shore birds and water fowl migrate south.
Anna’s hummingbirds (Calypte anna; male shown at left) are
back in the Sonoran Desert to breed, starting in late
September. Both male and female Anna's Hummingbirds
have dark bills, green backs, grayish-green undersides, and
lack of prominent eye stripes.
Elf owls (Micrathene whitneyi; below),
who have spent the summer in the
Sonoran Desert eating bugs, prepare
to migrate south before their prey is
killed off by colder temperatures.
October
Sun
Mon
Tue
4
5
11
12
Wed
Thu
Fri
Sat
1
2
3
6
7
8
9
10
13
14
15
16
17
* 1978,
AVHRR
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Record Low
(1897): 29F
Max Monthly Precipitation (1983): 5.78 inches
Record High
(1950): 104F
Photo credits: (Top) Will Elder, National Park Service; (Bottom) T. Beth Kinsey, the Firefly Forest; (Background) Jahan Kariyeva.
* Satellite launch dates.
November
Although November is the beginning of the winter precipitation season, the
precipitation that typically occurs is inadequate to satiate the parched
landscape. Temperatures continue to decline and the Sonoran Desert
generally experiences its first freezing temperatures of the season by the last
week of the month. The dry conditions combined with winds generated by
storms moving across the Great Basin to the north can result in dust storms.
Besides particles of soil, the wind can also disperse microscopic biota across
the desert, which is an important part of desert ecology. In the Sonoran
Desert, the soil dwelling fungi Coccidioides immitis and Coccidioides
posadasii are suspected of releasing their spores during this period. If these
spores are inhaled by humans they can cause a
Deciduous trees that inhabit the canyons of the
usually mild respiratory disease called “Valley Fever”.
Sonoran Desert lose their leaves after a brief
flash of color.
In the foothills surrounding the Sonoran Desert
grasses that prospered during the monsoonal rains
turn a golden brown.
Photo credits: (Top) Ted Myers, Arizona-Sonora Desert Museum; (Bottom) James Tamerius.
Young male mule
deer (Odocoileus
hemionus) are active,
rubbing the velvet
from their antlers in
preparation for
sparring in the winter.
November
Desert-mistletoe (Phoradendron spp.) -- a
hemiparasite -- begins to grow on
Ironwood, Mesquite, Palo Verde and
Acacia trees during November.
The phainopepla (Phainopepla nitens) is a
wintering bird in the Sonoran Desert.
Mistletoe berries are their primary food
source, although they eat insects as well.
Record Low
(1919): 19F
Max Monthly Precipitation (1905): 4.61 inches
Record High
(1924): 94F
Photo credits: (Top left ) Mark A. Dimmit, Arizona-Sonora Desert Museum; (Top right) Paul Berquist, Arizona-Sonora Desert
Museum; (Bottom left) T. Beth Kinsey, Firefly Forest
December
December is the month when the hunting activity
begins for species like mule deer, white tailed deer
(Odocoileus virginianus) and the desert big horn
sheep (Ovis canadensis), in many areas of the
Sonoran Desert.
Photo credits: (Top right and background) Rogelio Lizarraga; (Top left) Stephen Minter.
Winter crops abound in the Sonoran Desert, one of
the few places within the U.S. where you can grow
crops the whole year due to its mild temperatures
and abundant sunshine.
Pistachio
Agricultural produce unique to this region is sent
to the whole country where the weather
conditions are not as favorable as in the Sonoran
Desert in December.
Lettuce
Date palm
Chili pepper
December
Sun
Mon
Tue
Wed
Thu
Fri
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
21
22
23
24
25
26
28
29
30
31
20
Winter
Solstice
27
Drought Levels Based on
Monthly Streamflow
discharge, December
2007
Record Low
(1901): 10F
Photo credits: USGS, Arizona Water Science Center.
Sat
1
* 1999,
TERRA
Max Monthly Precipitation (1914): 5.85 inches
Record High
(1970): 88F
* Satellite launch dates.
Photo credits: Steve Amesbury.