Who Are These Cranes And Why Do We Have to Crane Our Necks to See Them?

-By Evan Ricaurte

 

Mississippi Sandhill Crane

Grus canadensis pulla

Already naturally secluded to a small area of Mississippi, this beautiful bird subspecies has been struggling to survive for as long as record exists of them thanks to human disturbance.

The Cranes

This subspecies of non-migratory Sandhill Cranes was first observed by Aldo Leopold in 1929 during a game survey of Jackson County, Mississippi. Standing about 4 feet tall, these birds have long necks and a grayish brown feather color topped with their most notable feature, a bright red crown on their heads. Due to their small population, much other information on them is actually recorded from the Florida or Alabama Sandhill Cranes and assumed to be similar enough to be used as an approximation for these as well. Their small population in this particular area comprises of a 1:1 sex ratio of birds whom can potentially reach the age of 20 years old under prime circumstances. Raising on average one offspring per year, a near 60% of hatchlings will survive. They reach independence 290 days after being born, but will not mate until two to three or even six years of age; at which point they will be able to be a part of the small population their current home can support.

The cranes have a very large diet of numerous types of insects, worms, fish; even birds and small mammals, all found throughout their habitat in Jackson County. In the winter they feed further away from their nesting habitats in nearby fields on crops which last through the seasons such as corn.  

Their Home

Source: U.S. Fish and Wildlife Recovery Plan

While of the six subspecies of the Sandhill Crane that exist, some such as the Louisiana cranes have even been known to be so populous in the past that they were considered a pest; none are so isolated and small in number as the Mississippi cranes. Residing in what is now the Mississippi Sandhill Crane National Wildlife Refuge, these cranes have always been living under very strained circumstances. This is largely in part due to the fact that nesting pairs each claim a large are of open savanna to raise their offspring. Of the 19,000 acres on the refuge for use of these cranes, only about 15,000 of that is able to be used for nesting, allowing for a mere 30 to 34 pairs of nesting cranes at any one time. This has resulted in population numbers that have never exceeded a few cranes over 100 since record has existed of the Mississippi subspecies. This ideal habitat for these birds is primarily wet pine savanna (grassland). These savannas combined with pine plantations and swamps which are also located on the small reserve where these birds reside provide a fully used, year-round habitat that these birds use.  

Effects on Their Lives

When the Mississippi Sandhill Cranes were first recorded in 1929 it was largely suspected that they had already been impacted by human hunting and logging activities which cut their habitat and numbers down to around those they are at now. Other man-made disturbances such as herbicide use and the construction of Interstate Highway 10 in the 1970’s lead to habitat disturbances despite backlash from the National Wildlife Federation. This event in particular though, did lead to a purchase of nearly 2,000 acres of land to be protected from further commercial development.

The largest strain on these cranes though, is simply lack of habitat. It is calculated that a population of nearly 200 cranes with at least 60 nesting pairs would be needed for a self-sustaining population; nearly double what exists today. For these reasons captive breeding and other recovery actions are in place to bring these cranes out of their threatened position.

Recovery

Listed as rare in 1968, and officially endangered in 1973, two recovery plan revisions for the Mississippi Sandhill cranes have been approved since the original in 1976. With the mission to create “a genetically viable, stable, self-sustaining, free-living Mississippi sandhill crane population” (Recovery Plan Third Revision). For recovery to be considered a success and meeting these criteria, the presence of the above mentioned 60 nesting pairs must be able to survive without a captive breeding program and other human intervention for 10 years, and then long term survival further after that. This is hoped to be achieved through increasing nesting habitat size and quality, and limiting human disturbances both direct and indirect (ex: pollution).

Multiple land purchases and designations have been made to bring the cranes’ land refuge to the size that it is now (19,273 acres), along with a captive breeding program based in Maryland that seems to have helped the crane population increase to the current maximum capacity for their current habitat area after a population drop in the 1960s and 70s.

In total, over 100 captive cranes have been released into the local Mississippi population over the length of the program, with survival rates of these birds on average being above 50%.

Population trend graph using data from U.S. Fish and Wildlife Recovery Plan

These actions along with others such as filling (man-made) ditches and road drains and maintain/creating natural barriers to separate the cranes from human activity have been successful so far in the implementation of this recovery plan.

Although these have been successful, the cranes are still simply holding onto an unstable population at the moment, with the biggest factor being space that is needed to create a natural and self-sustaining population in the long run. For this reason it is important that everyone who agrees that these unique and beautiful birds deserve to live despite human caused damages to their home and population speaks out. The cranes need more space to live and breed if they are ever to accomplish this, and while it will take effort and possible less than ideal actions such as redirecting highways or reorganizing privately owned land that can be used by the cranes. That being said, there is nothing that has stopped human motivation to make a change for the better before, so now everyone who can must help to be a part of this change, for the sake of the Mississippi Sandhill Cranes.

Information gathered from the Recovery Plan of the Mississippi Sandhill Crane as publicly available through the U.S. Fish and Wildlife Service

Images gathered via Google Image search of “Mississippi Sandhill Crane”