Exhibits: Desert Loop Trail

On the Desert Loop Trail you will have a rugged outdoor hiking experience. The loop is one half mile long, downhill and back up where you will encounter javelinas, coyotes and lizards in very naturalistic enclosures. 一路上，您还将了解到龙舌兰植物的神奇之处，并识别该地区原产于的各种豆科植物.

Currently on exhibit around the Desert Loop Trail:

• Coyotes
• Javelinas
• Lizards
• Blue Palo Verde
• Saguaro Cactus

Coyote

土狼无疑是最著名的沙漠动物，是西部的象征. 在美洲原住民的神话和传说中，他是著名的魔术师和智者. The coyote fascinates us with its intelligence and adapability. It can survive eating anything from saguaro fruit to roadkills, and is able to live in any habitat from cactus forest to the city. 尽管人类试图消灭土狼，但它已经扩大了在美国的活动范围. The coyote is not only intelligent, curious and playful, it has very keen senses that adapt it for survival-acute hearing, excellent vision, and an extremely sensitive sense of smell.

Coyotes are mostly social animals, living in small family groups. 在土狼家族更大的狩猎区域内是一个中心核心区域，那里是巢穴的所在地. 这个地区有气味标记和防御，特别是在春季和夏季. Coyotes urinate on bushes or other plants, then scrape the ground with their paws, which have scent glands. This leaves both olfactory and visual markers for other coyotes. Scats are also used to mark the territory.

土狼通常会在黄昏时分唱一首“早上好”的起床歌，为晚上的狩猎做准备. They also sing to communicate with neighbors, to keep track of family members, after summer rains, during the full moon, and it seems, just for fun.

Javelina

Javelina meander in loose groups, feeding as they move through an area. They dig up roots and bulbs with their sharp hooves or with their snouts. 它们吃多刺的仙人掌，包括仙人掌的刺，用它们的大犬齿撕下咬痕. 因为它们没有锋利的切齿，所以在刺梨上留下了很多纤维物质. Javelina chew as they walk, so bits and pieces fall from their mouths, sometimes leaving a short trail.

Javelina live in groups of 2 to 20 animals, the average being about 8 to 12. Each group defends a territory of about 700 to 800 acres, the size and boundaries varying in different seasons and different years; the territories include bed grounds and feeding areas, but they may overlap at critical resources, especially watering holes. 经验丰富的大母猪会领导母猪群，决定何时睡觉、进食或喝水. Javelina have no defined breeding season; the babies, usually twins, can be born in any month. Not many predators other than a mountain lion will attack an adult javelina, but the babies are also prey for coyotes, bobcats, and other animals.

Javelina have poor vision, relying instead on their sense of smell.

Blue Palo Verde

The green bark color of palo verdes is due to chlorophyll-bearing tissue. As do many other species, these trees conserve water by dropping their leaves during dry seasons, but palo verdes can still carry on some photosynthesis. Blue palo verde also drops its leaves in response to cool autumn temperatures.

这些花由许多种类的独居蜜蜂授粉，它们收集花粉并将其储存在洞穴中供幼虫食用. The main palo verde bee is Centris pallida, but there are 6 other species of Centris that visit palo verdes, in addition to sweat bees, several leaf-cutter bees, bumblebees, and carpenter bees. 蜜蜂专家Bob Schmalzel偶然发现了大约20种不同的蜜蜂同时在一棵palo verde树上觅食.

Saguaro

巨大的绿色树柱几乎吸引了每一位游客的注意, let alone a whole "forest" of them. The United States has even devoted a national park to this plant. 对于几个世纪以来一直生活在萨瓜罗栖息地的奥哈姆人来说，萨瓜罗甚至更为重要. 奥哈姆对仙人掌的高度尊重反映在他们对这种植物的许多创造故事中, which tend to share the common theme of people being turned into saguaros. These giant cacti are not plants to the Tohono O'odham; they're another form of humanity.

The saguaro is the largest cactus in the United States, commonly reaching 40 feet (12 m) tall; a few have attained 60 feet (18 m) and one was measured at 78 feet (23.8 m). The cylindrical stems are accordion-pleated; the ridges (outer "ribs") are lined with clusters of hard spines along the lower 8 feet (2.4 m) and flexible bristles above this height. White flowers are about 3 inches (8 cm) in diameter; they bloom mainly in May and June and are followed a month later by juicy red fruit.

壁虎的活动范围几乎完全局限于亚利桑那州南部和索诺拉西部. A few plants grow just across the political borders in California and Sinaloa. Saguaros reach their greatest abundance in Arizona Upland. Plants grow from sea level to about 4000 feet (1200 m). 在它们活动范围的北部，它们在温暖的南向斜坡上数量最多.

Water comprises most of the weight of the saguaro. 一根完全水合的大茎90%以上是水，每英尺重80磅(每米120公斤)。.

大型植物的大部分是水的体积保护它们免受极端温度的影响. 白天通过表面吸收的热量储存在大量的内部组织中, resulting in a fairly small temperature rise that doesn't reach a lethal level. 在较冷的夜晚，热量被缓慢地辐射并传导回空气中. 同样的热惯性通常使组织在寒冷的冬夜保持在零度以上.

Saguaros flower mostly near the stem tips during the dry foresummer; peak production is from mid-May to mid-June. 坚固的白色花朵在深夜开放，一直开放到第二天下午三点左右. 它们的直径约为3英寸(8厘米)，散发出一种像熟透的甜瓜一样的香气. The flowers are self-sterile; cross-pollination is necessary for fruit set.

这种水果在夏季干旱的高峰期大量成熟, and is nearly the only moist food available during this hottest, driest time of the year. 在六月下旬和七月初，它成为许多鸟类、哺乳动物和昆虫的主食. The primary effective seed dispersers are several species of fruit-eating birds, such as White-winged Doves, Gila Woodpeckers, and House finches. The birds digest the pulp, and the seeds pass through their guts intact. Birds also tend to defecate while perched in trees, thus depositing the seeds in favorable environments for establishment.

幼苗在最初的几年里生长非常缓慢，非常脆弱. They are tiny, heat- and frost- tender, soft-spined canteens. Rodents, rabbits, and birds eat the seedlings they can find, and many others succumb to desiccation or winter freezes. Nearly all survivors are located beneath the canopies of nurse plants, where they are sheltered from weather extremes and concealed from herbivores. Most desert plant species-not only saguaros-must begin life under nurse plants. Creosote bush, bursage, 而沙漠百日草是少数能够在完全暴露的地方成功生长的多年生植物之一.

In the Tucson Mountains, which averages 14 inches (355 mm) annual rainfall, a saguaro takes about 10 years to attain 1¼ inches (3.8 cm) in height and 30 years to reach 2 feet (61 cm). Saguaros begin to flower at about 8 feet tall (2.4 m), which takes an average of 55 years. 相比之下，萨瓜罗国家公园湿润的东部地区花了40年才首次开花(16英寸), 406 mm, 平均年降雨量)和75年干燥的风琴管仙人掌国家纪念碑(9英寸), 230 mm). No one has studied the populations near Yuma, which receive about 3¼ inches (90 mm) average annual rainfall.

树龄在50岁到100岁之间的时候(在图森山脉)，仙人掌可能会开始长出手臂。, usually just above the stem's maximum girth at about 7 to 9 feet (2.1 to 2.7 m) above-ground. 植物的枝数和总大小似乎与土壤和降雨有关. Saguaros on bajadas with finer, 保水能力强的土壤往往比陡坡上的土壤长得更大，产生更多的枝状突起, rocky slopes. A few saguaros have been observed with as many as 50 arms; many never grow arms. Saguaro arms always grow upwards. 在许多古老的射手身上看到的下垂的手臂是霜冻后枯萎的结果. The growing tips will turn upwards in time. There is a myth that arms are produced so as to balance the plants, but research shows arm-sprouting to be random. 许多射手座的手臂都长在主茎的同一侧.

Saguaros make excellent nesting places for many birds. The primary nesting associates are Gila woodpeckers and gilded flickers, both of which excavate nest holes in the fleshy stems. The plant seals the wound with scar tissue called callus, which quickly becomes very hard and impervious to microbial infection.

Woodpeckers usually excavate new nesting holes each year. 其他一些筑巢但不挖洞的鸟类占据了被遗弃的啄木鸟巢穴, including elf owls, house finches, ash-throated flycatchers, and purple martins. Invertebrates also inhabit them.

较大的鸟类，如红尾鹰，在主茎和臂之间的角度筑巢. Tall saguaros also make good hunting and resting perches for many birds. Cactus wrens sometimes nest among the arms or, less often, in a woodpecker cavity.

Fallen saguaros become homes for many small animals. Snakes, rodents, lizards, and invertebrates find shelter beneath and within them, until the community of reducers and decomposers completely recycle the remains.