One of my class values keeps defaulting to its original value

#include <iostream>
#include <vector>
#include <random>
#include <cmath>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <cmath>

int width  = 600;
int height = 600;

/*class V2D
{
  public:
    V2D(){}
    V2D(float _x, float _y)
    {
      x = _x;
      y = _y;
    }
    float x;
    float y;
};
*/
class Survivor
{
  public:
    float x;
    float y;
    float energy;
    int foodInPossession;
    float speed;
    //float size;
    float sense;
    float angleOfSense = -1;
    Survivor();
    Survivor(float _x, float _y, float _speed, float _sense)
    {
      x = _x;
      y = _y;
      speed             = _speed;
      energy            = 100;
      foodInPossession  = 0;
      //size              = _size;
      sense             = _sense;
    }
    void update()
    {
      float LO = 0;
      float HI = 360;
      float aom;
      if(angleOfSense==-1)
        aom = LO + static_cast <float> (rand()) /( static_cast <float> (RAND_MAX/(HI-LO)));
      else
        aom = angleOfSense;
      std::cout<<x<<" "<<y<<std::endl;
      x+= speed * sin(aom);
      y+= speed * cos(aom);
      std::cout<<x<<" "<<y<<std::endl;
    }
    bool onBorder()
    {
      return x == 0 || x == width || y == 0 || y == height;
    }
};
int main()
{
  std::vector<Survivor> survivors;
  survivors.push_back(Survivor(300, 300, 10, 1));
  GLFWwindow* window;
  if (!glfwInit())
    return 1;
  window = glfwCreateWindow(width, height, "Window", NULL, NULL);
  if (!window) {
    glfwTerminate();
    return 1;
  }
  glfwMakeContextCurrent(window);
  if(glewInit()!=GLEW_OK)
    std::cout<<"Error"<<std::endl;
  glEnable(GL_DEPTH_TEST);
  glMatrixMode(GL_PROJECTION);
  glfwGetFramebufferSize(window, &width, &height);
  glOrtho(0, width*(width/height), height, 0, -2, 2);
  while(!glfwWindowShouldClose(window)) {
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    glClearColor(0.11, 0.14, 0.17, 1);
    
    for(Survivor i : survivors)
    {
      if(!i.onBorder())
      {
        i.update();
      }
      glBegin(GL_QUADS);
      glColor3f(1, 1, 1);
      glVertex2f(i.x, i.y);
      glVertex2f(i.x + 1, i.y);
      glVertex2f(i.x + 1, i.y + 1);
      glVertex2f(i.x, i.y + 1);
      glEnd();
    }

    glfwSwapBuffers(window);
    glfwPollEvents();
  }
  glfwTerminate();
}