Ryan Myers Superblog 2 on Desert Tortoises

 

Ryan Myers

HIST 197

2/21/2020

Prof. Biggs

Superblog 2

     In order to further my knowledge on the Edwards Airforce Base Desert Tortoise population, I have decided to focus on the effectiveness of the Head Start Program. This Program is a conservation program which means to bolster the native population by keeping tortoises in captivity for the first years of their life. This is important, as desert tortoise mortality is the highest in the early years of life. The sources I found had various things to say in regards to the effectiveness of the head start program, which will be touched on source by source. Overall, these sources have helped me narrow my focus to the question of “how effective is the head start program on Edwards air force base?”.

 

Boarman, William, Kristan, William “Evaluation of Evidence Supporting the Effectiveness of Desert Tortoise Recovery Actions” U.S Geological Survey 2006 https://pubs.usgs.gov/sir/2006/5143/sir_2006-5143.pdf

This is a 2006 evaluation of threats to the desert tortoise population and possible resolutions to some of these threats. The date of the publication is important to note, as it was published only in the early days of the head start program. This means that the program itself is not fully evaluated at the time of this publication. The paper still as many relevant points, however. It is interesting that among the threats noted as “strong” military land use is one of these. In addition, the solutions of tortoise fencing and reservations are noted as positive. This means that even in the early days of the head start program, the issue of military use was known, and so was the solution of tortoise pens.

 

Casem, Giancarlo “Edwards Environmental Management, San Diego Zoo Release 116 Tortoises” 412th Test Wing November 03 2020 https://www.edwards.af.mil/News/Article/2404160/edwards-environmental-management-san-diego-zoo-release-116-tortoises/

This is the most recent of the sources cited and is on the most recent release of a desert tortoise cohort in 2020. In this case 116 tortoises were successfully released. The article speaks quite well of the head start program and cites the successful release of over 500 tortoises. It even mentions improvements made to the program since 2004, including the implementation of isolation pens for ill tortoises. Despite these positive developments, the article does note some issues with the program. These issues include invasive species brought in by human developments, like ravens, and further habitat loss.

Foster, et. al “Arsenic Species in Scute (Shell Plate) and Lung Tissues of Desert Tortoises” American Geophysical Union 2009 https://ui.adsabs.harvard.edu/abs/2009AGUFM.B32B..04F/abstract

This article is one of the ones that notes one of the negative impacts/possibilities of the head start program; that being the presence of arsenic in some desert tortoise populations. The presence of arsenic is attributed to the human activities of mining and military usage. While mining is beyond the scope of this paper, military usage is not. This is especially relevant as the head start pens are on military land. Arsenic is quite toxic to many animals and has contributed to health issues in some tortoises. As a result, head start pens can, in some circumstances, contribute to health issues in some tortoises.

 

Mack, et al “Crowding Affects Health, Growth, and Behavior in Headstart Pens for Agassiz's Desert Tortoise” Chelonian Conservation and Biology 2018 https://bioone.org/journals/chelonian-conservation-and-biology/volume-17/issue-1/CCB-1248.1/Crowding-Affects-Health-Growth-and-Behavior-in-Headstart-Pens-for/10.2744/CCB-1248.1.short

This article observed the health of eight head start pen cohorts. It cited many issues with the head start program, and this paper speaks of the health issues caused by crowding in some of the pens. The issues spoken here are connected to crowding in the pens and nutritional deficiencies. Many of these nutritional issues were caused by the fact that the juveniles often had to eat invasive grasses as opposed to native plants. These issues cumulated in some horrendous statistics including the majority of tortoises (59.5%) having protruding spinal columns and stunted growth rates.

 

Sanchez, Stacy “Desert Tortoise get head start to survival” 95th Air Base Wing Public Affairs May 14 2008 https://www.edwards.af.mil/News/Article/396073/desert-tortoises-get-head-start-to-survival/

 

This is an article from the earlier days of the head start program detailing its goals and some of its methods. It speaks of the selection and examination methods used on tortoise eggs which are to be raised in the pens. In addition, it speaks of how tortoises that are a year or younger are too small to be reliably released. Finally, this article provides images of both the pens and tortoises in said pens. 

 

 

 

A picture the pens. Note the netting and circular shape

 

 

 

A juvenile tortoise. Note how small it is, it is no wonder most tortoise fatalities are in the early years of life.

 

 

 

Comments

  1. David BiggsFebruary 23, 2021 at 10:36 AM

    Hi Ryan. What is the historical argument in your research? I see the documents from af.mil on head start, but maybe you can include more sources looking at the history of military endangered species conservation? when did it begin? why?

    ReplyDelete

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