California condors are the largest birds in North America. They may weigh up to 25 pounds and have wingspans of 9 1/2 feet. California condors have bare heads and necks, dull gray-black feathers, and blunt claws. They have a triangle-shaped patch of white, visible only when airborne, that adorns the underside of their wings.
California condors can soar on warm thermal updrafts for hours, reaching speeds of more than 55 miles per hour and altitudes of 15,000 feet.
Normally, California condors do not become sexually mature until the age of 6 and may not start breeding until age 7 or 8. They nest in caves or clefts on cliffs that usually have nearby trees for roosting and a clear approach for easy take-offs and landings. Typically, an adult pair lays one egg every other year, with the fledgling being dependent upon its parents through the next breeding season.
Like all vultures, condors are carrion-eaters. They prefer large dead animals like deer, cattle, and sheep, but will also eat rodents and more rarely, fish. If a meal has been particularly big, they may have to spend hours on the ground or a low branch before they can take off again. Condors are fastidious birds — after eating, they clean their heads and necks by rubbing them on grass, rocks, or tree branches. Condors also bathe frequently and spend hours preening and drying their feathers.
Condors were probably never very numerous in North America. The species once ranged along the entire Pacific Coast from British Columbia to Baja California. Fossils have been found as far east as Texas, Florida, and New York. More recently, however, they were confined to a horseshoe-shaped area north of Los Angeles.
For years, no one knew precisely how many California condors existed, although they have been considered to be a declining species since the 1890s. One estimate put their number at 100 in the early 1940s. Another indicated there were 50 to 60 in the early 1960s. By the late 1970s, the estimate had dropped to 25 to 30 birds.
Nor, despite years of study, can scientists pinpoint the reason for the bird’s decline. Some factors include illegal collection of condors and their eggs, poisoning from substances put out by ranchers to eradicate livestock predators, poisoning from ingesting lead fragments from bullets embedded in animal carcasses the condors feed on, and collisions with structures such as power lines. In addition, the roads, cities, housing tracts, and weekend mountain retreats of modern civilization have replaced much of the open country condors need to find food. Their slow rate of reproduction and years spent reaching breeding maturity undoubtedly make the condor population as a whole more vulnerable to these threats.
Recognizing the California condor’s perilous state, the U.S. Fish and Wildlife Service listed the bird as an endangered species in 1967 (under a law that preceded the Endangered Species Act of 1973), meaning it was considered in danger of extinction throughout all or a significant portion of its range. The Fish and Wildlife Service, the California Department of Fish and Game, and the National Audubon Society, among other government and private groups, began a joint effort in 1979 to study and preserve the bird.
As part of this effort, biologists captured birds, weighed and measured them, and fitted some with tags and radio transmitters so they could be monitored and identified after being released. Biologists learned about the condors’ feeding, mating, and chick-rearing habits, as well as their habitat needs. They also confirmed that California condor pairs that lost an egg would lay a second or even a third one.
To increase the condors’ egg production, the biologists began removing eggs laid in the wild in 1983. The eggs were taken to either the San Diego Wild Animal Park or the Los Angeles Zoo for hatching. The first California condor hatched in captivity in 1983. Nicknamed “Sisquoc,” this condor and subsequent chicks hatched from wild-laid eggs were raised in boxes that simulated the caves their parents used. Zookeepers kept human contact to a minimum by feeding the chicks with hand puppets made to look like adult condors.
Meanwhile, researchers began capturing young condors in order to start breeding them as quickly as possible before the wild population declined further. Bringing immature, non- breeding birds into captivity would speed up the time it would take to create a viable, breeding population. The Andean condor, a closely related species that inhabits areas in South America, had bred successfully in captivity and some captive-born birds have been released in the wild, giving biologists good reason to be optimistic about similar success for the California condor.Computer Viruses
A computer virus is an illegal and potentially damaging computer program designed to infect other software by attaching itself to any software it contacts. In many cases, virus programs are designed to damage computer systems maliciously by destroying of corrupting data. If the infected software is transferred to or accessed by another computer system, the virus spreads to the other system. Viruses have become a serious problem in recent years, and currently, thousands of known virus programs exist (Reed 85-102)b.
Three types of viruses are a boot sector virus, file virus, and Trojan horse virus. A boot sector virus infects the. When the infected boot program executes, the virus is loaded into the computers memory. Once the Virus is in memory, it can spread to any floppy disk inserted into the computer. A file virus inserts virus codes into program files The virus then spreads to any program that accesses the infected file. A Trogan horse virus (named after the Greek myth) hides within or is designed to look like s legitimate program.
Some viruses interrupt processing by freezing a computer system temporarily and then displaying sounds or messages. Other viruses contain time bombs or logic bombs. A time bomb is a program that performs an activity on a particular date.A logic bomb is a program that performs an activity when a certain action occurs, such as an employee being terminated. A worm, which is similar to a virus, copies itself repeatedly until no more memory of disk space remains.
To find computer viruses, anti-virus programs have been developed. Besides detecting viruses, anti-virus programs also have utilities to remove or repair infected programs and files. Some damaged files cannot be repaired and must be replaced with uninfected archive files. The table below outlines some techniques used to protect computer systems.
Techniques for virus Protection and System Archive
Using Virus Protection SoftwareBacking Up Your System
Install virus protection software on every computer systemDevelop a regular plan for copying and storing important data and program files.
Before use, scan every floppy disk with a virus scan program to check for viruses.Implement a backup plan and adhere to its guidelines.
Check all programs downloaded from the Internet or bulletin boards for viruses.Keep copies of files in fireproof safes or vaults or off site.
If your system becomes virus infected and you have questions, contact the National Computer Security Association (NCSA) for low-cost assistance (Elmhurst, 6 Nov. 1998).
Chambers, Anita R., and Zachary W. Peters. Protecting Against Virus Attacks. Computers May 1998: 45-62.
Elmhurst, Mark. Virus Infection: Where to Obtain Assistance Word 97, Project 3.
htpp://www.scite.com/wd97/pr3.htm (6 Nov 1998).
Reed, Margaret E. An Introduction to Using Computers. Chicago: West Davidson Jones
Publishing Company, 1998.