At the core of adaptive deer management, the balance between environment and animal is essential. Like all big game animals, with Sika the concept is the same. Males venture out to feed zones (‘fattening country’) up to 16km in spring/summer and post rut, while females remain all year round in limited territory (‘breeding country’) within matriarchal family groups. Because of this, the best indicators of herd health at place lie within the hinds. Their skeletal size, reproductive status and condition gives us a direct indication of what the health of the environment they are/have been living in is.
The best time to gauge herd indicators is in winter and early spring. This is when there is the most demand on the environment as the seasonal vegetation growth has slowed, the hinds are sustaining the previous year’s fawn and (if they have conceived) have another small foetus inside. This is also the most ethical time to take breeding hinds as the previous year’s fawn is not solely dependent on the Hind. The fawn’s rumen system has developed enough to be able digest vegetation and will be able to survive, and the hind’s new foetus is in the early stages of development.
There are 4 key indicators for hind autopsy.
1. Jaw size and age
The jaw of an animal gives us an indication of skeletal size, and the age can be determined through tooth eruption patterns and (for older deer) confirmation can be achieved by cutting through and performing an analysis of the 1st molar (4th tooth).
Skeletal size gives us a direct indication of how much nutrients the animal has had for the first 3 – 4 years of their life (when all skeletal growth occurs).
2. In Milk (evidence of last year’s fawn).
Sika generally wean their fawns at 6-8 months. Milk can be seen when squeezing the nipple to release the milk from the udder, or visually by cutting it.
3. In Fawn
After a successful mating, there will be a foetus inside the uterus. This can be seen as early as a month after breeding.
The condition of the hind alongside the above three indicators is a very critical piece of the puzzle, particularly in winter and early spring. This gives us a direct indication of how much nutrients she is getting from her environment while there is increased demand on her body (if she has been sustaining a previous fawn and/or new foetus inside). A condition score system of 1 – 5 is used:
1 – skinny; 2 – light; 3 – average; 4 – good; 5 – fat.
OTHER REPRODUCTIVE INDICTORS
Evidence of previous fawning can also be observed when dissecting the uterus See hind 1. When the placenta detaches from the uterus wall, it leaves scaring. This can be a good tool to gauge how many times the hind has given birth. This is best seen in the early stages in the pregnancy (June/July). In late term pregnancies when the foetus is large and the uterus structure has become more complex, it is much harder to see.
Left – The uterus of this hind was dissected during the roar, the 3XRed placentomes can be observed. This indicates a receptive Hind in the process of cycling.
SAMPLE IN PRACTICE
Below is a sample of 4 hinds that have been shot over a 3-month period and autopsied within 1 square kilometre of each other from early June to early September 2022.
This is accessible public land comprised of predominantly red beech with some thick pepperwood and mingimingi understorey, and manuka/kanuka.
This location receives a relative level of hunting pressure, mostly during the summer and roar.
|Jaw Size (Heel)
WHAT THIS TELLS US
This sample tells us that in this location the environment and vegetation is in a healthy state and there is capacity to sustain deer with all key health indicators in good shape. This is the Balance we are aiming for. Hind 2 is worth noting the exceptional condition while in milk and fawn. The Jaw sizes across the whole sample are above average when plotted on to the 2020 – 2022 Sika Foundation dataset comprised of jaw data from Kaimanawa/Kaweka Forest parks, and other private land blocks throughout the Central North Island Sika range.
CONTRIBUTE TO SIKA FOUNDATION JAW AND DATA PROGRAMME
This data is a valuable tool for adaptive deer management. To help the Sika Foundation better understand areas of stress throughout the Central North Island Sika range, next time you shoot a deer (particularly hinds), remove the jaw, assess her key health indicators and fill in a Jaw card and hunter data sheet.